Publications by year
In Press
Wedell N, Price T, Verspoor R (In Press). Ancient gene drives: an evolutionary paradox.
Proceedings of the Royal Society B: Biological Sciences Full text.
Hosken DJ, Taylor, M. Hoyle, K. Higgins, S. Wedell N (In Press). Attractive males have greater success in sperm competition. Current Biology
Singh KS, Hosken DJ, Wedell N, ffrench-Constant R, Bass C, Baxter S, Paszkiewicz K, Sharma MD (In Press). De novo genome assembly of the meadow brown butterfly, Maniola jurtina.
Abstract:
De novo genome assembly of the meadow brown butterfly, Maniola jurtina
AbstractBackgroundMeadow brown butterflies (Maniola jurtina) on the Isles of Scilly represent an ideal model in which to dissect the links between genotype, phenotype and long-term patterns of selection in the wild - a largely unfulfilled but fundamental aim of modern biology. To meet this aim, a clear description of genotype is required.FindingsHere we present the draft genome sequence of M. jurtina to serve as an initial genetic resource for this species. Seven libraries were constructed using DNA from multiple wild caught females and sequenced using Illumina, PacBio RSII and MinION technology. A novel hybrid assembly approach was employed to generate a final assembly with an N50 of 214 kb (longest scaffold 2.9 Mb). The genome encodes a total of 36,294 genes. 90.3% and 88.7% of core BUSCO (Benchmarking Universal Single-Copy Orthologs) Arthropoda and Insecta gene sets were recovered as complete single-copies from this assembly. Comparisons with 17 other Lepidopteran species placed 86.5% of the assembled genes in orthogroups.ConclusionsOur results provide the first high-quality draft genome and annotation of the butterfly M. jurtina.
Abstract.
Sutter A, Keiko O, Delany K, Store S, Travers L, Wedell N (In Press). Flexible polyandry in female flies is 1 an adaptive response to infertile males.
Behavioral Ecology Full text.
Wiberg RAW, Price TAR, Wedell N, Ritchie MG (In Press). Identifying genomic markers associated with female re-mating rate in Drosophila pseudoobscura by replicated bulk segregant analysis.
Abstract:
Identifying genomic markers associated with female re-mating rate in Drosophila pseudoobscura by replicated bulk segregant analysis
ABSTRACTIdentifying loci associated with a phenotype is a critical step in many evolutionary studies. Most methods require large sample sizes or breeding designs that can be prohibitively difficult. Here we apply a rarely used approach to identify SNP loci associated with a complex phenotype. We mate siblings from isofemale lines isolate genotypes from three wild populations. After phenotyping we perform whole genome sequencing of isofemale lines from the extremes of the phenotypic distribution of each population and identify SNPs that are consistently fixed for alternative alleles across line pairs. The focal phenotype is female remating rate in the fly Drosophila pseudoobscura, defined as the willingness of a female to mate with a second male after her first mating. This is an integral part of mating system evolution, sexual selection and sexual conflict, and is a quantitative polygenic trait.About 200 SNPs are consistently fixed for alternate alleles in the three pairs of isofemale lines. We use different simulation approaches to explore how many SNPs would be expected to be fixed. We find the surprising result that we uncover fewer observed fixed SNPs than are expected by either simulation approach. We also complete functional analyses of these SNPs. Many lie near genes or regulatory regions known to be involved in Drosophila courtship and mating behaviours, and some have previously been associated with re-mating rates in Genome-Wide Association Studies. Given the small sample size, these results should be treated with caution. Nevertheless, this study suggests that even from a relatively small number of isofemale lines established from wild populations, it is possible to identify candidate loci potentially associated with a complex quantitative trait. However, further work is required to understand modelling the expected distribution of differences.
Abstract.
Hosken DJ, Hawkes MF, Gamble CE, Turner ECR, Carey MR, Wedell N (In Press). Intralocus sexual conflict and insecticide resistance.
Proceedings B Full text.
Ingleby FC, Lewis Z, Wedell N (In Press). Level of sperm comeptition promotes evolution of male ejaculate allocation patterns in a moth.
Animal BehaviourAbstract:
Level of sperm comeptition promotes evolution of male ejaculate allocation patterns in a moth
The risk and intensity of sperm competition can influence male adaptations that ultimately affect male fertilisation success, for example investment in sperm production and strategic sperm allocation patterns. Previous studies have examined male behavioural responses to variation in immediate levels of sperm competition. Here we quantified the evolutionary responses of male adaptations resulting from long-term manipulation of the level of sperm competition. By varying the adult sex ratio of populations of the Indian meal moth Plodia interpunctella we successfully altered the frequency of male and female copulations, and thus the level of sperm competition experienced by males. As predicted by theory, males evolving under higher levels of sperm competition increased investment in sperm production and differed in their sperm allocation patterns across matings, compared to males evolving under intermediate and low levels of sperm competition. However, we found no evidence for trade-offs between ejaculate components, or between total sperm production and male body size in this species.
Abstract.
Wigmore, C. Hodgson, D.J. Wedell, N. (In Press). Multiple mating increases female fitness in <em>Drosophila simulans</em>. Animal Behaviour
Wedell N (In Press). Selfish genes and sexual selection: the impact of genomic parasites on host reproduction.
Journal of Zoology Full text.
Verspoor R, Price T, Wedell N (In Press). Selfish genetic elements and male fertility. Philosophical Transactions of the Royal Society B: Biological Sciences
Taylor ML, Price TAR, Skeats A, Wedell N (In Press). Temperature can shape a cline in polyandry, but only genetic variation can sustain it over time.
Behavioral EcologyAbstract:
Temperature can shape a cline in polyandry, but only genetic variation can sustain it over time
Multiple mating by females (polyandry) is a widespread behavior occurring in diverse taxa, species, and populations. Polyandry can also vary widely within species, and individual populations, so that both monandrous and polyandrous females occur together. Genetic differences can explain some of this intraspecific variation in polyandry, but environmental factors are also likely to play a role. One environmental factor that influences many fundamental biological processes is temperature. Higher temperatures have been shown to directly increase re-mating in laboratory studies of insects. In the longer term, high temperature could also help to drive the evolution of larger-scale patterns of behavior by changing the context-dependent balance of costs and benefits of polyandry across environments. We examined the relative influence of rearing and mating temperature on female re-mating in populations of Drosophila pseudoobscura that show a latitudinal cline in polyandry in nature, using a range of ecologically relevant temperatures. We found that females of all genotypes re-mated more at cooler temperatures, which fits with the observation of higher average frequencies of polyandry at higher latitudes in this species. However, the impact of temperature was outweighed by the strong genetic control of re-mating in females in this species. It is likely that genetic factors provide the primary explanation for the latitudinal cline in polyandry in this species.
Abstract.
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Hosken DJ, Alonzo SH, Wedell N (In Press). Why aren’t females ornamented more often?.
Hosken DJ, Alonzo SH, Wedell N (In Press). Why aren’t signals of female quality more common?.
Full text.
2020
Singh KS, Hosken DJ, Wedell N, Ffrench-Constant R, Bass C, Baxter S, Paszkiewicz K, Sharma MD (2020). De Novo Genome Assembly of the Meadow Brown Butterfly, Maniola jurtina.
G3 (Bethesda),
10(5), 1477-1484.
Abstract:
De Novo Genome Assembly of the Meadow Brown Butterfly, Maniola jurtina.
Meadow brown butterflies (Maniola jurtina) on the Isles of Scilly represent an ideal model in which to dissect the links between genotype, phenotype and long-term patterns of selection in the wild - a largely unfulfilled but fundamental aim of modern biology. To meet this aim, a clear description of genotype is required. Here we present the draft genome sequence of M. jurtina to serve as a founding genetic resource for this species. Seven libraries were constructed using pooled DNA from five wild caught spotted females and sequenced using Illumina, PacBio RSII and MinION technology. A novel hybrid assembly approach was employed to generate a final assembly with an N50 of 214 kb (longest scaffold 2.9 Mb). The sequence assembly described here predicts a gene count of 36,294 and includes variants and gene duplicates from five genotypes. Core BUSCO (Benchmarking Universal Single-Copy Orthologs) gene sets of Arthropoda and Insecta recovered 90.5% and 88.7% complete and single-copy genes respectively. Comparisons with 17 other Lepidopteran species placed 86.5% of the assembled genes in orthogroups. Our results provide the first high-quality draft genome and annotation of the butterfly M. jurtina.
Abstract.
Author URL.
2019
Larner W, Price T, Holman L, Wedell N (2019). An X-linked meiotic drive allele has strong, recessive fitness costs in female Drosophila pseudoobscura.
Proceedings of the Royal Society B: Biological Sciences,
286(1916).
Abstract:
An X-linked meiotic drive allele has strong, recessive fitness costs in female Drosophila pseudoobscura
© 2019 the Author(s) Published by the Royal Society. Selfish 'meiotic drive' alleles are transmitted to more than 50% of offspring, allowing them to rapidly invade populations even if they reduce the fitness of individuals carrying them. Theory predicts that drivers should either fix or go extinct, yet some drivers defy these predictions by persisting at low, stable frequencies for decades. One possible explanation for this discrepancy is that drivers are especially costly when homozygous, although empirical tests of this idea are rare and equivocal. Here, we measure the fitness of female Drosophila pseudoobscura carrying zero, one or two copies of the X-linked driver sex ratio (SR). SR had strong negative effects on female offspring production and the probability of reproductive failure, and these effects were largely similar across four genetic backgrounds. SR was especially costly when homozygous. We used our fitness measurements to parametrize a population genetic model, and found that the female fitness costs observed here can explain the puzzlingly low allele frequency of SR in nature. We also use the model to show how spatial variation in female mating behaviour, fitness costs of SR and the reduced siring success of SR males can jointly explain the north-south cline in SR frequencies across North America.
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Ono K, Price T, Wedell N (2019). Does mating negatively affect female immune defences in insects?.
Animal Biology,
69, 117-136.
Full text.
McNamara KB, Dougherty LR, Wedell N, Simmons LW (2019). Experimental evolution reveals divergence in female genital teeth morphology in response to sexual conflict intensity in a moth.
J Evol Biol,
32(5), 519-524.
Abstract:
Experimental evolution reveals divergence in female genital teeth morphology in response to sexual conflict intensity in a moth.
The rapid evolutionary divergence of male genital structures under sexual selection is well documented. However, variation in female genital traits and the potential for sexual conflict to drive the coevolution between male and female traits has only recently received attention. In many lepidopterans, females possess genital teeth (collectively, signa). Comparative studies suggest these teeth, involved in the deflation of spermatophores, may have coevolved with male spermatophore thickness via sexually antagonistic coevolution in a contest over the rate of deflation of spermatophores within the reproductive tract. We tested the hypothesis that sexual conflict should generate coevolution between genital teeth and spermatophore morphology by examining these traits under experimental manipulation of sexual conflict intensity. Using micro-CT scanning, we examined spermatophore and teeth morphology in populations of the Indian moth, Plodia interpunctella, which had been evolving for 110 generations under different adult sex-ratio biases. We found divergence in female signa morphology in response to sexual conflict: females from female-biased populations (reduced sexual conflict) developed wider signa. However, we found no evidence of coevolution between signa traits and spermatophore thickness as reported from comparative studies.
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Arundell KL, Bojko J, Wedell N, Dunn AM (2019). Fluctuating asymmetry, parasitism and reproductive fitness in two species of gammarid crustacean.
Diseases of Aquatic Organisms,
136(1), 37-49.
Abstract:
Fluctuating asymmetry, parasitism and reproductive fitness in two species of gammarid crustacean
© Inter-Research 2019 Fluctuating asymmetry (FA), defined as random deviations from perfect bilateral symmetry, is assumed to reflect developmental instability. FA is predicted to increase in response to environmental stress, including parasite infection. In addition, based on theory we predict a higher FA in sexually selected traits, due to their greater sensitivity to stress. We investigated the relationships between FA, parasitism and reproductive fitness in 2 species of gammarid crustacean, incorporating both sexual and non-sexual traits. We tested the hypothesis that gammarids infected by vertically transmitted Microsporidia will display higher levels of FA than those infected by horizontally transmitted trematodes, because vertically transmitted Microsporidia can be present at the earliest stages of host development. We found little evidence for a relationship between FA and fecundity in Gammarus spp.; however, egg diameter for infected female Gammarus duebeni was significantly smaller than uninfected female G. duebeni. FA was not correlated with brood size in females or with sperm number in males. In contrast to our prediction, we report a lower relative FA in response to sexual traits than non-sexual traits. However, FA in sexual traits was found to be higher in males than females, supporting the theory that sexual selection leads to increased FA. Additionally, we report a negative correlation between FA and both trematode (Podocotyle atomon) and PCR-positive microsporidian (Nosema granulosis and Dictyocoela duebenum) infections and interpret these results in the context of the parasites' transmission strategies. FA in G. duebeni and G. zaddachi appears to associate with trematode and microsporidian presence, although reproductive fitness is less altered by infection.
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Wedell N, Price TAR, Lindholm AK (2019). Gene drive: progress and prospects.
Proceedings of the Royal Society B: Biological Sciences,
286(1917), 20192709-20192709.
Abstract:
Gene drive: progress and prospects
Gene drive is a naturally occurring phenomenon in which selfish genetic elements manipulate gametogenesis and reproduction to increase their own transmission to the next generation. Currently, there is great excitement about the potential of harnessing such systems to control major pest and vector populations. If synthetic gene drive systems can be constructed and applied to key species, they may be able to rapidly spread either modifying or eliminating the targeted populations. This approach has been lauded as a revolutionary and efficient mechanism to control insect-borne diseases and crop pests. Driving endosymbionts have already been deployed to combat the transmission of dengue and Zika virus in mosquitoes. However, there are a variety of barriers to successfully implementing gene drive techniques in wild populations. There is a risk that targeted organisms will rapidly evolve an ability to suppress the synthetic drive system, rendering it ineffective. There are also potential risks of synthetic gene drivers invading non-target species or populations. This Special Feature covers the current state of affairs regarding both natural and synthetic gene drive systems with the aim to identify knowledge gaps. By understanding how natural drive systems spread through populations, we may be able to better predict the outcomes of synthetic drive release.
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Sutter A, Travers LM, Weedon M, Oku K, Price TAR, Wedell N (2019). No selection for change in polyandry under experimental evolution.
J Evol Biol,
32(7), 717-730.
Abstract:
No selection for change in polyandry under experimental evolution.
What drives mating system variation is a major question in evolutionary biology. Female multiple mating (polyandry) has diverse evolutionary consequences, and there are many potential benefits and costs of polyandry. However, our understanding of its evolution is biased towards studies enforcing monandry in polyandrous species. What drives and maintains variation in polyandry between individuals, genotypes, populations and species remains poorly understood. Genetic variation in polyandry may be actively maintained by selection, or arise by chance if polyandry is selectively neutral. In Drosophila pseudoobscura, there is genetic variation in polyandry between and within populations. We used isofemale lines to found replicate populations with high or low initial levels of polyandry and tracked polyandry under experimental evolution over seven generations. Polyandry remained relatively stable, reflecting the starting frequencies of the experimental populations. There were no clear fitness differences between high versus low polyandry genotypes, and there was no signature of balancing selection. We confirmed these patterns in direct comparisons between evolved and ancestral females and found no consequences of polyandry for female fecundity. The absence of differential selection even when initiating populations with major differences in polyandry casts some doubt on the importance of polyandry for female fitness.
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Arundell KL, Dubuffet A, Wedell N, Bojko J, Rogers MSJ, Dunn AM (2019). Podocotyle atomon (Trematoda: Digenea) impacts reproductive behaviour, survival and physiology in Gammarus zaddachi (Amphipoda).
Diseases of Aquatic Organisms,
136(1), 51-62.
Abstract:
Podocotyle atomon (Trematoda: Digenea) impacts reproductive behaviour, survival and physiology in Gammarus zaddachi (Amphipoda)
© Inter-Research 2019 the Trematoda are a group of phylogenetically diverse metazoan parasites that exhibit complex life cycles that often pass through invertebrate and vertebrate hosts. Some trematodes influence their host's behaviour to benefit transmission. Their parasitic influence may impact host population size by inhibiting an individual's reproductive capacity. We assessed the impact of infection by Podocotyle atomon on the reproductive behaviour and fecundity of its amphipod intermediate host, Gammarus zaddachi, using laboratory and field studies. Parasite prevalence was high in the field, with males more likely to be infected (prevalence in males 64%, in females 39%). Males also suffered a higher parasite burden than females. Infected females were less active, but we found no evidence for a reduction in female reproductive success. Infected females also had comparable pairing success to uninfected females. In males, infection reduced survival and fecundity, with mortality being highest, and sperm numbers lowest, in heavily infected individuals. Trematode parasites are sometimes associated with altered host fecundity, but studies often lack the relevant experimental data to explore the evolution of the trait. We discuss this among information specific to the effect of P. atomon infection in G. zaddachi.
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Hawkes MF, Duffy E, Joag R, Skeats A, Radwan J, Wedell N, Sharma MD, Hosken DJ, Troscianko J (2019). Sexual selection drives the evolution of male wing interference patterns.
Proc Biol Sci,
286(1903).
Abstract:
Sexual selection drives the evolution of male wing interference patterns.
The seemingly transparent wings of many insects have recently been found to display unexpected structural coloration. These structural colours (wing interference patterns: WIPs) may be involved in species recognition and mate choice, yet little is known about the evolutionary processes that shape them. Furthermore, to date investigations of WIPs have not fully considered how they are actually perceived by the viewers' colour vision. Here, we use multispectral digital imaging and a model of Drosophila vision to compare WIPs of male and female Drosophila simulans from replicate populations forced to evolve with or without sexual selection for 68 generations. We show that WIPs modelled in Drosophila vision evolve in response to sexual selection and provide evidence that WIPs correlate with male sexual attractiveness. These findings add a new element to the otherwise well-described Drosophila courtship display and confirm that wing colours evolve through sexual selection.
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Wedell N (2019). Sperm competition. In (Ed)
Encyclopedia of Animal Behavior, 498-504.
Abstract:
Sperm competition
Abstract.
Duffy E, Archer CR, Sharma MD, Prus M, Joag RA, Radwan J, Wedell N, Hosken DJ (2019). Wolbachia infection can bias estimates of intralocus sexual conflict.
Ecology and Evolution,
9(1), 328-338.
Abstract:
Wolbachia infection can bias estimates of intralocus sexual conflict
© 2018 the Authors. Ecology and Evolution published by John Wiley. &. Sons Ltd. Males and females share most of their genome and develop many of the same traits. However, each sex frequently has different optimal values for these shared traits, creating intralocus sexual conflict. This conflict has been observed in wild and laboratory populations of insects and affects important evolutionary processes such as sexual selection, the maintenance of genetic variation, and possibly even speciation. Given the broad impacts of intralocus conflict, accurately detecting and measuring it is important. A common way to detect intralocus sexual conflict is to calculate the intersexual genetic correlation for fitness, with negative values suggesting conflict. Here, we highlight a potential confounder of this measure—cytoplasmic incompatibility caused by the intracellular parasite Wolbachia. Infection with Wolbachia can generate negative intersexual genetic correlations for fitness in insects, suggestive of intralocus sexual conflict. This is because cytoplasmic incompatibility reduces the fitness of uninfected females mated to infected males, while uninfected males will not suffer reductions in fitness if they mate with infected females and may even be fitter than infected males. This can lead to strong negative intersexual genetic correlations for fitness, mimicking intralocus conflict. We illustrate this issue using simulations and then present Drosophila simulans data that show how reproductive incompatibilities caused by Wolbachia infection can generate signals of intralocus sexual conflict. Given that Wolbachia infection in insect populations is pervasive, but populations usually contain both infected and uninfected individuals providing scope for cytoplasmic incompatibility, this is an important consideration for sexual conflict research but one which, to date, has been largely underappreciated.
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2018
Hosken DJ, Archer R, House C, Wedell N (2018). Penis evolution across species: divergence and diversity.
Nature Reviews Urology Full text.
2017
Jungwirth A, Wedell N, Bshary R, Milinski M (2017). Animal personalities: an empty placeholder feigning understanding: a comment on Beekman and Jordan.
BEHAVIORAL ECOLOGY,
28(3), 629-630.
Author URL.
Baxter SW, Hoffman JI, Tregenza T, Wedell N, Hosken DJ (2017). EB Ford revisited: assessing the long-term stability of wing-spot patterns and population genetic structure of the meadow brown butterfly on the Isles of Scilly.
Heredity (Edinb),
118(4), 322-329.
Abstract:
EB Ford revisited: assessing the long-term stability of wing-spot patterns and population genetic structure of the meadow brown butterfly on the Isles of Scilly.
Understanding selection in the wild remains a major aim of evolutionary ecology and work by Ford and colleagues on the meadow brown butterfly Maniola jurtina did much to ignite this agenda. A great deal of their work was conducted during the 1950s on the Isles of Scilly. They documented island-specific wing-spot patterns that remained consistent over about a decade, but patterns on some islands changed after environmental perturbation. It was suggested that these wing-spot patterns reflected island-specific selection and that there was little migration between islands. However, genetic studies to test the underlying assumption of restricted migration are lacking and it is also unknown whether the originally described wing-spot patterns have persisted over time. We therefore collected female butterflies from five of Ford's original study locations, including three large islands (St Mary's, St Martin's and Tresco) and two small islands (Tean and St Helen's). Wing-spot patterns had not changed appreciably over time on three of the islands (two large and one small), but were significantly different on the other two. Furthermore, analysis of 176 amplified fragment length polymorphisms revealed significant genome-wide differentiation among the five islands. Our findings are consistent with Ford's conclusions that despite the close proximity of these islands, there is restricted gene flow among them.
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Wedell N, Hosken DJ (2017). Three billion years of research
and development.
NATURE ECOLOGY & EVOLUTION,
1 Full text.
2016
Perry JC, Joag R, Hosken DJ, Wedell N, Radwan J, Wigby S (2016). Experimental evolution under hyper-promiscuity in Drosophila melanogaster.
BMC Evol Biol,
16(1).
Abstract:
Experimental evolution under hyper-promiscuity in Drosophila melanogaster.
BACKGROUND: the number of partners that individuals mate with over their lifetime is a defining feature of mating systems, and variation in mate number is thought to be a major driver of sexual evolution. Although previous research has investigated the evolutionary consequences of reductions in the number of mates, we know little about the costs and benefits of increased numbers of mates. Here, we use a genetic manipulation of mating frequency in Drosophila melanogaster to create a novel, highly promiscuous mating system. We generated D. melanogaster populations in which flies were deficient for the sex peptide receptor (SPR) gene - resulting in SPR- females that mated more frequently - and genetically-matched control populations, and allowed them to evolve for 55 generations. At several time-points during this experimental evolution, we assayed behavioural, morphological and transcriptional reproductive phenotypes expected to evolve in response to increased population mating frequencies. RESULTS: We found that males from the high mating frequency SPR- populations evolved decreased ability to inhibit the receptivity of their mates and decreased copulation duration, in line with predictions of decreased per-mating investment with increased sperm competition. Unexpectedly, SPR- population males also evolved weakly increased sex peptide (SP) gene expression. Males from SPR- populations initially (i.e. before experimental evolution) exhibited more frequent courtship and faster time until mating relative to controls, but over evolutionary time these differences diminished or reversed. CONCLUSIONS: in response to experimentally increased mating frequency, SPR- males evolved behavioural responses consistent with decreased male post-copulatory investment at each mating and decreased overall pre-copulatory performance. The trend towards increased SP gene expression might plausibly relate to functional differences in the two domains of the SP protein. Our study highlights the utility of genetic manipulations of animal social and sexual environments coupled with experimental evolution.
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Lindholm AK, Dyer KA, Firman RC, Fishman L, Forstmeier W, Holman L, Johannesson H, Knief U, Kokko H, Larracuente AM, et al (2016). The Ecology and Evolutionary Dynamics of Meiotic Drive.
Trends Ecol Evol,
31(4), 315-326.
Abstract:
The Ecology and Evolutionary Dynamics of Meiotic Drive.
Meiotic drivers are genetic variants that selfishly manipulate the production of gametes to increase their own rate of transmission, often to the detriment of the rest of the genome and the individual that carries them. This genomic conflict potentially occurs whenever a diploid organism produces a haploid stage, and can have profound evolutionary impacts on gametogenesis, fertility, individual behaviour, mating system, population survival, and reproductive isolation. Multiple research teams are developing artificial drive systems for pest control, utilising the transmission advantage of drive to alter or exterminate target species. Here, we review current knowledge of how natural drive systems function, how drivers spread through natural populations, and the factors that limit their invasion.
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Chargé R, Wedell N, Lindstedt C, Hämäläinen L, Övermark E, Mappes J (2016). Variation in male fertility in a polymorphic moth, Parasemia plantaginis.
Animal Behaviour,
111, 33-40.
Abstract:
Variation in male fertility in a polymorphic moth, Parasemia plantaginis
© 2015 the Association for the Study of Animal Behaviour. The maintenance of multiple morphs in warning signals is enigmatic because directional selection through predator avoidance should lead to the rapid loss of such variation. Opposing natural and sexual selection is a good candidate driving the maintenance of multiple male morphs but it also includes another enigma: when warning signal efficiency differs between male morphs, why would females choose a phenotype with lower survival? We tested the hypothesis that indirect responses to selection on correlated characters through sexual selection may substantially shape the evolution of male coloration. If male phenotypes differ in their fertilization ability, female choice against the best surviving phenotype can evolve. The wood tiger moth, Parasemia plantaginis, has two coexisting male morphs in Europe. Previous studies have shown that yellow males are better defended against predators, but that white males have a higher mating success. We examined differences in fertility between white and yellow males in terms of sperm production, number of sperm transferred and rate of sperm replenishment, and association between these fertility traits, female mate choice and reproductive output. If white morphs have greater fertility than yellow males, then this could explain why females prefer to mate with white males. However, we did not find any difference between male colour morphs either in mating probability, fertility (i.e. sperm availability and sperm transferred) or reproductive success (i.e. number of eggs laid and hatching success). We discuss our results in relation to context-dependent mating success and maintenance of colour polymorphism within populations.
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Giraldo-Perez P, Herrera P, Campbell A, Taylor ML, Skeats A, Aggio R, Wedell N, Price TAR (2016). Winter is coming: hibernation reverses the outcome of sperm competition in a fly.
J Evol Biol,
29(2), 371-379.
Abstract:
Winter is coming: hibernation reverses the outcome of sperm competition in a fly.
Sperm commonly compete within females to fertilize ova, but research has focused on short-term sperm storage: sperm that are maintained in a female for only a few days or weeks before use. In nature, females of many species store sperm for months or years, often during periods of environmental stress, such as cold winters. Here we examine the outcome of sperm competition in the fruit fly Drosophila pseudoobscura, simulating the conditions in which females survive winter. We mated females to two males and then stored the female for up to 120 days at 4°C. We found that the outcome of sperm competition was consistent when sperm from two males was stored for 0, 1 or 30 days, with the last male to mate fathering most of the offspring. However, when females were stored in the cold for 120 days, the last male to mate fathered less than 5% of the offspring. Moreover, when sperm were stored long term the first male fathered almost all offspring even when he carried a meiotic driving sex chromosome that drastically reduces sperm competitive success under short-term storage conditions. This suggests that long-term sperm storage can radically alter the outcome of sperm competition.
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2015
Holman L, Price TAR, Wedell N, Kokko H (2015). Coevolutionary dynamics of polyandry and sex-linked meiotic drive.
Evolution,
69(3), 709-720.
Abstract:
Coevolutionary dynamics of polyandry and sex-linked meiotic drive
© 2015 the Author(s). Segregation distorters located on sex chromosomes are predicted to sweep to fixation and cause extinction via a shortage of one sex, but in nature they are often found at low, stable frequencies. One potential resolution to this longstanding puzzle involves female multiple mating (polyandry). Because many meiotic drivers severely reduce the sperm competitive ability of their male carriers, females are predicted to evolve more frequent polyandry and thereby promote sperm competition when a meiotic driver invades. Consequently, the driving chromosome's relative fitness should decline, halting or reversing its spread. We used formal modeling to show that this initially appealing hypothesis cannot resolve the puzzle alone: other selective pressures (e.g. low fitness of drive homozygotes) are required to establish a stable meiotic drive polymorphism. However, polyandry and meiotic drive can strongly affect one another's frequency, and polyandrous populations may be resistant to the invasion of rare drive mutants.
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Wedell N (2015). Nina Wedell.
CURRENT BIOLOGY,
25(22), R1062-R1063.
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Taylor ML, Skeats A, Wilson AJ, Price TAR, Wedell N (2015). Opposite environmental and genetic influences on body size in North American Drosophila pseudoobscura Evolutionary ecology and behaviour.
BMC Evolutionary Biology,
15(1).
Abstract:
Opposite environmental and genetic influences on body size in North American Drosophila pseudoobscura Evolutionary ecology and behaviour
© 2015 Taylor et al.; licensee BioMed Central. Background: Populations of a species often differ in key traits. However, it is rarely known whether these differences are associated with genetic variation and evolved differences between populations, or are instead simply a plastic response to environmental differences experienced by the populations. Here we examine the interplay of plasticity and direct genetic control by investigating temperature-size relationships in populations of Drosophila pseudoobscura from North America. We used 27 isolines from three populations and exposed them to four temperature regimes (16°C, 20°C, 23°C, 26°C) to examine environmental, genetic and genotype-by-environment sources of variance in wing size. Results: By far the largest contribution to variation in wing size came from rearing temperature, with the largest flies emerging from the coolest temperatures. However, we also found a genetic signature that was counter to this pattern as flies originating from the northern, cooler population were consistently smaller than conspecifics from more southern, warmer populations when reared under the same laboratory conditions. Conclusions: We conclude that local selection on body size appears to be acting counter to the environmental effect of temperature. We find no evidence that local adaptation in phenotypic plasticity can explain this result, and suggest indirect selection on traits closely linked with body size, or patterns of chromosome inversion may instead be driving this relationship.
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Rostant WG, Kay C, Wedell N, Hosken DJ (2015). Sexual conflict maintains variation at an insecticide resistance locus.
BMC Biol,
13Abstract:
Sexual conflict maintains variation at an insecticide resistance locus.
BACKGROUND: the maintenance of genetic variation through sexually antagonistic selection is controversial, partly because specific sexually-antagonistic alleles have not been identified. The Drosophila DDT resistance allele (DDT-R) is an exception. This allele increases female fitness, but simultaneously decreases male fitness, and it has been suggested that this sexual antagonism could explain why polymorphism was maintained at the locus prior to DDT use. We tested this possibility using a genetic model and then used evolving fly populations to test model predictions. RESULTS: Theory predicted that sexual antagonism is able to maintain genetic variation at this locus, hence explaining why DDT-R did not fix prior to DDT use despite increasing female fitness, and experimentally evolving fly populations verified theoretical predictions. CONCLUSIONS: This demonstrates that sexually antagonistic selection can maintain genetic variation and explains the DDT-R frequencies observed in nature.
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2014
Herrera P, Taylor ML, Skeats A, Price TAR, Wedell N (2014). Can patterns of chromosome inversions in Drosophila pseudoobscura predict polyandry across a geographical cline?.
ECOLOGY AND EVOLUTION,
4(15), 3072-3081.
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Mank JE, Hosken DJ, Wedell N (2014). Conflict on the sex chromosomes: cause, effect, and complexity.
Cold Spring Harb Perspect Biol,
6(12).
Abstract:
Conflict on the sex chromosomes: cause, effect, and complexity.
Intralocus sexual conflict and intragenomic conflict both affect sex chromosome evolution and can in extreme cases even cause the complete turnover of sex chromosomes. Additionally, established sex chromosomes often become the focus of heightened conflict. This creates a tangled relationship between sex chromosomes and conflict with respect to cause and effect. To further complicate matters, sexual and intragenomic conflict may exacerbate one another and thereby further fuel sex chromosome change. Different magnitudes and foci of conflict offer potential explanations for lineage-specific variation in sex chromosome evolution and answer long-standing questions as to why some sex chromosomes are remarkably stable, whereas others show rapid rates of evolutionary change.
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Price TAR, Bretman A, Gradilla AC, Reger J, Taylor ML, Giraldo-Perez P, Campbell A, Hurst GDD, Wedell N (2014). Does polyandry control population sex ratio via regulation of a selfish gene?.
Proc Biol Sci,
281(1783).
Abstract:
Does polyandry control population sex ratio via regulation of a selfish gene?
The extent of female multiple mating (polyandry) can strongly impact on the intensity of sexual selection, sexual conflict, and the evolution of cooperation and sociality. More subtly, polyandry may protect populations against intragenomic conflicts that result from the invasion of deleterious selfish genetic elements (SGEs). SGEs commonly impair sperm production, and so are likely to be unsuccessful in sperm competition, potentially reducing their transmission in polyandrous populations. Here, we test this prediction in nature. We demonstrate a heritable latitudinal cline in the degree of polyandry in the fruitfly Drosophila pseudoobscura across the USA, with northern population females remating more frequently in both the field and the laboratory. High remating was associated with low frequency of a sex-ratio-distorting meiotic driver in natural populations. In the laboratory, polyandry directly controls the frequency of the driver by undermining its transmission. Hence we suggest that the cline in polyandry represents an important contributor to the cline in sex ratio in nature. Furthermore, as the meiotic driver causes sex ratio bias, variation in polyandry may ultimately determine population sex ratio across the USA, a dramatic impact of female mating decisions. As SGEs are ubiquitous it is likely that the reduction of intragenomic conflict by polyandry is widespread.
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Duffy E, Joag R, Radwan J, Wedell N, Hosken DJ (2014). Inbreeding alters intersexual fitness correlations in Drosophila simulans.
ECOLOGY AND EVOLUTION,
4(17), 3330-3338.
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Taylor ML, Price TAR, Wedell N (2014). Polyandry in nature: a global analysis.
Trends Ecol Evol,
29(7), 376-383.
Abstract:
Polyandry in nature: a global analysis.
A popular notion in sexual selection is that females are polyandrous and their offspring are commonly sired by more than a single male. We now have large-scale evidence from natural populations to be able to verify this assumption. Although we concur that polyandry is a generally common and ubiquitous phenomenon, we emphasise that it remains variable. In particular, the persistence of single paternity, both within and between populations, requires more careful consideration. We also explore an intriguing relation of polyandry with latitude. Several recent large-scale analyses of the relations between key population fitness variables, such as heterozygosity, effective population size (Ne), and inbreeding coefficients, make it possible to examine the global effects of polyandry on population fitness for the first time.
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Hornett EA, Moran B, Reynolds LA, Charlat S, Tazzyman S, Wedell N, Jiggins CD, Hurst GDD (2014). The evolution of sex ratio distorter suppression affects a 25 cM genomic region in the butterfly Hypolimnas bolina.
PLoS Genet,
10(12).
Abstract:
The evolution of sex ratio distorter suppression affects a 25 cM genomic region in the butterfly Hypolimnas bolina.
Symbionts that distort their host's sex ratio by favouring the production and survival of females are common in arthropods. Their presence produces intense Fisherian selection to return the sex ratio to parity, typified by the rapid spread of host 'suppressor' loci that restore male survival/development. In this study, we investigated the genomic impact of a selective event of this kind in the butterfly Hypolimnas bolina. Through linkage mapping, we first identified a genomic region that was necessary for males to survive Wolbachia-induced male-killing. We then investigated the genomic impact of the rapid spread of suppression, which converted the Samoan population of this butterfly from a 100:1 female-biased sex ratio in 2001 to a 1:1 sex ratio by 2006. Models of this process revealed the potential for a chromosome-wide effect. To measure the impact of this episode of selection directly, the pattern of genetic variation before and after the spread of suppression was compared. Changes in allele frequencies were observed over a 25 cM region surrounding the suppressor locus, with a reduction in overall diversity observed at loci that co-segregate with the suppressor. These changes exceeded those expected from drift and occurred alongside the generation of linkage disequilibrium. The presence of novel allelic variants in 2006 suggests that the suppressor was likely to have been introduced via immigration rather than through de novo mutation. In addition, further sampling in 2010 indicated that many of the introduced variants were lost or had declined in frequency since 2006. We hypothesize that this loss may have resulted from a period of purifying selection, removing deleterious material that introgressed during the initial sweep. Our observations of the impact of suppression of sex ratio distorting activity reveal a very wide genomic imprint, reflecting its status as one of the strongest selective forces in nature.
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Awrahman ZA, Champion de Crespigny F, Wedell N (2014). The impact of Wolbachia, male age and mating history on cytoplasmic incompatibility and sperm transfer in Drosophila simulans.
Journal of Evolutionary Biology,
27(1), 1-10.
Abstract:
The impact of Wolbachia, male age and mating history on cytoplasmic incompatibility and sperm transfer in Drosophila simulans
Most insects harbour a variety of maternally inherited endosymbionts, the most widespread being Wolbachia pipientis that commonly induce cytoplasmic incompatibility (CI) and reduced hatching success in crosses between infected males and uninfected females. High temperature and increasing male age are known to reduce the level of CI in a variety of insects. In Drosophila simulans, infected males have been shown to mate at a higher rate than uninfected males. By examining the impact of mating rate independent of age, this study investigates whether a high mating rate confers an advantage to infected males through restoring their compatibility with uninfected females over and above the effect of age. The impact of Wolbachia infection, male mating rate and age on the number of sperm transferred to females during copulation and how it relates to CI expression was also assessed. As predicted, we found that reproductive compatibility was restored faster in males that mate at higher rate than that of low mating and virgin males, and that the effect of mating history was over and above the effect of male age. Nonvirgin infected males transferred fewer sperm than uninfected males during copulation, and mating at a high rate resulted in the transfer of fewer sperm per mating irrespective of infection status. These results indicate that the advantage to infected males of mating at a high rate is through restoration of reproductive compatibility with uninfected females, whereas uninfected males appear to trade off the number of sperm transferred per mating with female encounter rate and success in sperm competition. This study highlights the importance Wolbachia may play in sexual selection by affecting male reproductive strategies. © 2013 European Society for Evolutionary Biology.
Abstract.
Full text.
Awrahman ZA, Champion de Crespigny F, Wedell N (2014). The impact of Wolbachia, male age and mating history on cytoplasmic incompatibility and sperm transfer in Drosophila simulans.
J Evol Biol,
27(1), 1-10.
Abstract:
The impact of Wolbachia, male age and mating history on cytoplasmic incompatibility and sperm transfer in Drosophila simulans.
Most insects harbour a variety of maternally inherited endosymbionts, the most widespread being Wolbachia pipientis that commonly induce cytoplasmic incompatibility (CI) and reduced hatching success in crosses between infected males and uninfected females. High temperature and increasing male age are known to reduce the level of CI in a variety of insects. In Drosophila simulans, infected males have been shown to mate at a higher rate than uninfected males. By examining the impact of mating rate independent of age, this study investigates whether a high mating rate confers an advantage to infected males through restoring their compatibility with uninfected females over and above the effect of age. The impact of Wolbachia infection, male mating rate and age on the number of sperm transferred to females during copulation and how it relates to CI expression was also assessed. As predicted, we found that reproductive compatibility was restored faster in males that mate at higher rate than that of low mating and virgin males, and that the effect of mating history was over and above the effect of male age. Nonvirgin infected males transferred fewer sperm than uninfected males during copulation, and mating at a high rate resulted in the transfer of fewer sperm per mating irrespective of infection status. These results indicate that the advantage to infected males of mating at a high rate is through restoration of reproductive compatibility with uninfected females, whereas uninfected males appear to trade off the number of sperm transferred per mating with female encounter rate and success in sperm competition. This study highlights the importance Wolbachia may play in sexual selection by affecting male reproductive strategies.
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Author URL.
Arundell KL, Wedell N, Dunn AM (2014). The impact of predation risk and of parasitic infection on parental care in brooding crustaceans.
Animal Behaviour,
96, 97-105.
Abstract:
The impact of predation risk and of parasitic infection on parental care in brooding crustaceans
Parental care is common in vertebrates, but less common in invertebrates, tending to occur in species that have relatively few young that can be protected from the physical or biotic environment. Individuals will be selected to trade off current and future reproductive success, leading to adaptive changes in brood care behaviour in response to predation risk. Investment in brood care may also be reduced as a result of costs of parasitic infection. Here we investigated the impact of predator cues and of parasite infection on brood care behaviour in amphipod crustaceans. We found no evidence for any reduction in brooding behaviour or reproductive success in response to infection by vertically transmitted microsporidian parasites. This may reflect the mechanism of parasite transmission, as vertically transmitted parasites rely on host reproduction to pass to the next generation. However, we found evidence for changes in brood care behaviour in response to increased risk of predation. Larger Crangonyx pseudogracilis females, with higher oxygen demands for their broods, showed a reduction in active brood care when exposed to predator cues. Additionally, Gammarus duebeni were found to reduce brooding duration in response to predator cues; we suggest that this earlier release of juveniles is likely to enhance survival of the brood, by spreading the risk of predation on juveniles. © 2014 the Association for the Study of Animal Behaviour.
Abstract.
2013
McNamara KB, Wedell N, Simmons LW (2013). Experimental evolution reveals trade-offs between mating and immunity.
Biology Letters,
9(4).
Abstract:
Experimental evolution reveals trade-offs between mating and immunity
Immune system maintenance and upregulation is costly. Sexual selection intensity, which increases male investment into reproductive traits, is expected to create trade-offs with immune function. We assayed phenoloxidase (PO) and lytic activity of individuals from populations of the Indian meal moth, Plodia interpunctella, which had been evolving under different intensities of sexual selection.We found significant divergence among populations, with males from female-biased populations having lower PO activity than males from balanced sex ratio or male-biased populations. There was no divergence in anti-bacterial lytic activity. Our data suggest that it is the increased male mating demands in female-biased populations that tradesoff against immunity, and not the increased investment in sperm transfer per mating that characterizes male-biased populations.
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Arundell KL, Wedell N, Dunn AM (2013). Perceived risk of sperm competition affects sperm investment in a mate-guarding amphipod.
Animal BehaviourAbstract:
Perceived risk of sperm competition affects sperm investment in a mate-guarding amphipod
Sperm competition theory predicts that males should allocate sperm prudently in response to perceived return on investment. It is predicted that males should invest in greater sperm stores and allocate more sperm to females in response to increased risk of sperm competition (absence versus presence of competitors), but allocate fewer sperm when intensity of sperm competition (number of competitors) is high, owing to diminishing returns. We tested these predictions in Gammarus duebeni, an amphipod with precopula mate guarding. Contrary to predictions, we found no difference in sperm allocation to females in response to increased risk or intensity of sperm competition. In addition, we observed a decrease in both sperm numbers and sperm length when males were kept with potential competitors for extended periods of time, particularly in larger males. We suggest that G. duebeni invests in mate guarding over sperm production/allocation in response to sperm competition, and we discuss whether competition for resources may also affect investment in ejaculate production. © 2013 the Association for the Study of Animal Behaviour.
Abstract.
Mank JE, Wedell N, Hosken DJ (2013). Polyandry and sex-specific gene expression.
Philos Trans R Soc Lond B Biol Sci,
368(1613).
Abstract:
Polyandry and sex-specific gene expression.
Polyandry is widespread in nature, and has important evolutionary consequences for the evolution of sexual dimorphism and sexual conflict. Although many of the phenotypic consequences of polyandry have been elucidated, our understanding of the impacts of polyandry and mating systems on the genome is in its infancy. Polyandry can intensify selection on sexual characters and generate more intense sexual conflict. This has consequences for sequence evolution, but also for sex-biased gene expression, which acts as a link between mating systems, sex-specific selection and the evolution of sexual dimorphism. We discuss this and the remarkable confluence of sexual-conflict theory and patterns of gene expression, while also making predictions about transcription patterns, mating systems and sexual conflict. Gene expression is a key link in the genotype-phenotype chain, and although in its early stages, understanding the sexual selection-transcription relationship will provide significant insights into this critical association.
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Author URL.
Mank JE, Wedell N, Hosken DJ (2013). Polyandry and sex-specific gene expression.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences,
368(1613).
Abstract:
Polyandry and sex-specific gene expression.
Polyandry is widespread in nature, and has important evolutionary consequences for the evolution of sexual dimorphism and sexual conflict. Although many of the phenotypic consequences of polyandry have been elucidated, our understanding of the impacts of polyandry and mating systems on the genome is in its infancy. Polyandry can intensify selection on sexual characters and generate more intense sexual conflict. This has consequences for sequence evolution, but also for sex-biased gene expression, which acts as a link between mating systems, sex-specific selection and the evolution of sexual dimorphism. We discuss this and the remarkable confluence of sexual-conflict theory and patterns of gene expression, while also making predictions about transcription patterns, mating systems and sexual conflict. Gene expression is a key link in the genotype-phenotype chain, and although in its early stages, understanding the sexual selection-transcription relationship will provide significant insights into this critical association.
Abstract.
House CM, Lewis Z, Hodgson DJ, Wedell N, Sharma MD, Hunt J, Hosken DJ (2013). Sexual and natural selection both influence male genital evolution.
PLoS One,
8(5).
Abstract:
Sexual and natural selection both influence male genital evolution.
Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on the genital-arch lobes of male Drosophila simulans. Replicate populations were forced to evolve under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and two temperature regimes, 25°C (relaxed natural selection) or 27°C (elevated natural selection) in a fully factorial design. We found that natural and sexual selection plus their interaction caused genital evolution. Natural selection caused some aspects of genital form to evolve away from their sexually selected shape, whereas natural and sexual selection operated in the same direction for other shape components. Additionally, sexual and natural selection tended to favour larger genitals. Thus we find that the underlying selection driving genital evolution is complex, does not only involve sexual selection, and that natural selection and sexual selection do not always act antagonistically.
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Wedell N (2013). The dynamic relationship between polyandry and selfish genetic elements.
Philosophical Transactions of the Royal Society B: Biological Sciences,
368(1613).
Abstract:
The dynamic relationship between polyandry and selfish genetic elements
Selfish genetic elements (SGEs) are ubiquitous in eukaryotes and bacteria, and make up a large part of the genome. They frequently target sperm to increase their transmission success, but these manipulations are often associated with reduced male fertility. Low fertility of SGE-carrying males is suggested to promote polyandry as a female strategy to bias paternity against male carriers. Support for this hypothesis is found in several taxa, where SGE-carrying males have reduced sperm competitive ability. In contrast, when SGEs give rise to reproductive incompatibilities between SGE-carrying males and females, polyandry is not necessarily favoured, irrespective of the detrimental impact on male fertility. This is due to the frequency-dependent nature of these incompatibilities, because they will decrease in the population as the frequency of SGEs increases. However, reduced fertility of SGE-carrying males can prevent the successful population invasion of SGEs. In addition, SGEs can directly influence male and female mating behaviour, mating rates and reproductive traits (e.g. female reproductive tract length and male sperm). This reveals a potent and dynamic interaction between SGEs and polyandry highlighting the potential to generate sexual selection and conflict, but also indicates that polyandry can promote harmony within the genome by undermining the spread of SGEs. © 2013 the Author(s) Published by the Royal Society. All rights reserved.
Abstract.
Wedell N (2013). The dynamic relationship between polyandry and selfish genetic elements.
Philos Trans R Soc Lond B Biol Sci,
368(1613).
Abstract:
The dynamic relationship between polyandry and selfish genetic elements.
Selfish genetic elements (SGEs) are ubiquitous in eukaryotes and bacteria, and make up a large part of the genome. They frequently target sperm to increase their transmission success, but these manipulations are often associated with reduced male fertility. Low fertility of SGE-carrying males is suggested to promote polyandry as a female strategy to bias paternity against male carriers. Support for this hypothesis is found in several taxa, where SGE-carrying males have reduced sperm competitive ability. In contrast, when SGEs give rise to reproductive incompatibilities between SGE-carrying males and females, polyandry is not necessarily favoured, irrespective of the detrimental impact on male fertility. This is due to the frequency-dependent nature of these incompatibilities, because they will decrease in the population as the frequency of SGEs increases. However, reduced fertility of SGE-carrying males can prevent the successful population invasion of SGEs. In addition, SGEs can directly influence male and female mating behaviour, mating rates and reproductive traits (e.g. female reproductive tract length and male sperm). This reveals a potent and dynamic interaction between SGEs and polyandry highlighting the potential to generate sexual selection and conflict, but also indicates that polyandry can promote harmony within the genome by undermining the spread of SGEs.
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Author URL.
Lewis Z, Lizé A, Wedell N (2013). The interplay between different stages of reproduction in males of the moth Plodia interpunctella. Animal Behaviour
Lewis Z, Lizé A, Wedell N (2013). The interplay between different stages of reproduction in males of the moth Plodia interpunctella.
Animal Behaviour,
86(5), 917-922.
Abstract:
The interplay between different stages of reproduction in males of the moth Plodia interpunctella
As a result of female remating, sexual selection can operate both before and after copulation, yet studies of sexual selection on males tend to focus on individual episodes of reproduction in isolation. We examined whether different episodes of sexual selection are related in the sperm-polymorphic Indian meal moth, Plodia interpunctella. We found that the ability to mate with nonvirgin females determined male precopulatory reproductive success. In addition, males that transferred more sperm during their first mating were better at both sperm competition and reducing females' propensity to remate, suggesting that sperm production and transfer are key determinants of reproductive success in this species. However, no relationships were found between traits contributing to pre- versus postcopulatory sexual selection. Our results illustrate the importance of considering variation in all aspects of male reproductive success when examining sexual selection. © 2013 the Association for the Study of Animal Behaviour.
Abstract.
Pizzari T, Wedell N (2013). The polyandry revolution. Philosophical Transactions of the Royal Society B: Biological Sciences, 368(1613).
2012
Harrison PW, Mank JE, Wedell N (2012). Incomplete Sex Chromosome Dosage Compensation in the Indian Meal Moth, Plodia interpunctella, Based on De Novo Transcriptome Assembly.
GENOME BIOLOGY AND EVOLUTION,
4(11), 1118-1126.
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Price TAR, Lewis Z, Smith DT, Hurst GDD, Wedell N (2012). No evidence of mate discrimination against males carrying a sex ratio distorter in Drosophila pseudoobscura.
Behavioral Ecology and Sociobiology,
66(4), 561-568.
Abstract:
No evidence of mate discrimination against males carrying a sex ratio distorter in Drosophila pseudoobscura
Selfish genetic elements (SGEs) that spread by manipulating spermatogenesis often have highly deleterious effects on males that carry them. Females that mate with male carriers of SGEs can also suffer significant costs: they receive fewer and poorer-quality sperm, their offspring will inherit the deleterious allele, and the sex ratio of their offspring will be biased towards the more common sex. To counter these costs, females are therefore expected to prefer to mate with males that do not carry sex ratio distorters or other deleterious selfish genetic elements. However, despite the potential costs, there are few examples of female choice against males carrying SGEs. We searched for evidence of a female preference in fruit fly Drosophila pseudoobscura against males carrying a costly meiotic driving X-chromosome Sex Ratio (SR). In a series of five non-competitive mate preference experiments, we find no evidence that females prefer to mate with non-SR males. Our use of five separate experiments, involving more than 800 females, makes it unlikely that this lack of a difference was due to low power or simple chance. We suggest that the lack of female choice against SGE-carrying males may be due to strong selection on SGEs to be indistinguishable from alternative alleles. Furthermore, polyandry, either in direct response to receiving an ejaculate from an SGE-carrying male or carried out indiscriminately when at risk of mating with carriers, may be an alternative response by females to limit the exposure of their offspring to SGEs. © 2011 Springer-Verlag.
Abstract.
Price TAR, Hoskyns RC, Rapley H, Evans JC, Wedell N (2012). No evidence that temperature-related fertility differences influence the distribution of a selfish genetic element.
Functional Ecology,
26(3), 657-665.
Abstract:
No evidence that temperature-related fertility differences influence the distribution of a selfish genetic element
Selfish genetic elements (SGEs) are universal and can have major evolutionary and ecological impacts, but their ecology is not well understood. Most SGEs have stable population dynamics, but the reasons for this are rarely known. Several SGEs are distributed along latitudinal frequency clines, providing an opportunity to examine why these clines are stable. 2.Latitudinal temperature changes are a strong contender for an underlying environmental cause of such clines. Both SGEs and extreme temperatures commonly affect male fertility. If these factors interact to reduce male fertility, this could be the cause of the observed latitudinal clines. 3.The meiotic driving X-chromosome sex ratio (SR), found in the fruit fly Drosophila pseudoobscura, is distributed in a cline across North America, being absent in Canada and increasing in frequency southward to 30% at the Mexico/USA border. This cline has been stable for at least 50years, despite considerable gene flow between populations. If SR males have decreased fertility in the colder Northern populations, this could undermine the success of SR and cause this cline. 4.Here, we examine the fertility of males reared at high and low temperatures. We find that both SR and non-SR males have reduced fertility at high temperatures. However, SR males show disproportionally lower fertility at high temperatures than non-SR males. 5.The geographical distribution of SR suggests the opposite should be true; SR males should be more successful at high temperatures than low ones, as SR is more common in the South, hence the observed temperature-related fertility differences of males cannot be the cause of the cline in SR in nature. 6.This study finds that the reduction in male fertility commonly caused by SGEs is temperature dependent. However, although these interactions are likely to be important for the ecology of SGEs, they do not necessarily provide the explanation for the observed latitudinal clines in SR. © 2012 the Authors. Functional Ecology © 2012 British Ecological Society.
Abstract.
Price TAR, Hoskyns RC, Rapley H, Evans JC, Wedell N (2012). No evidence that temperature-related fertility differences influence the distribution of a selfish genetic element. Functional Ecology
Smith DT, Sirot LK, Wolfner MF, Hosken DJ, Wedell N (2012). The consequences of genetic variation in sex peptide expression levels for egg laying and retention in females.
Heredity,
109(4), 222-225.
Abstract:
The consequences of genetic variation in sex peptide expression levels for egg laying and retention in females
The accessory gland proteins (Acps) that male Drosophila melanogaster produce and transfer to females during copulation are key to male and female fitness. One Acp, the sex peptide (SP), is largely responsible for a dramatic increase in female egg laying and decrease in female receptivity after copulation. While genetic variation in male SP expression levels correlate with refractory period duration in females, it is unknown whether male SP expression influences female egg laying or if any effect of SP is mediated by SP retention in the female reproductive tract. Here we measured the amount of SP retained in the female reproductive tract after mating and female egg laying after copulating with virgin males. We found no correlation between male SP expression levels and egg laying, or the amount of SP in the female reproductive tract after mating. Additionally, the amount of SP retained in the female did not influence egg laying. These finding suggests that additional factors, such as variation in other Acps, are important for the retention of SP in females and its quantitative effects on egg laying. It also shows that egg laying and refractory period response to SP is at least partially uncoupled. © 2012 Macmillan Publishers Limited all rights reserved.
Abstract.
Smith DT, Sirot LK, Wolfner MF, Hosken DJ, Wedell N (2012). The consequences of genetic variation in sex peptide expression levels for egg laying and retention in females.
Heredity (Edinb),
109(4), 222-225.
Abstract:
The consequences of genetic variation in sex peptide expression levels for egg laying and retention in females.
The accessory gland proteins (Acps) that male Drosophila melanogaster produce and transfer to females during copulation are key to male and female fitness. One Acp, the sex peptide (SP), is largely responsible for a dramatic increase in female egg laying and decrease in female receptivity after copulation. While genetic variation in male SP expression levels correlate with refractory period duration in females, it is unknown whether male SP expression influences female egg laying or if any effect of SP is mediated by SP retention in the female reproductive tract. Here we measured the amount of SP retained in the female reproductive tract after mating and female egg laying after copulating with virgin males. We found no correlation between male SP expression levels and egg laying, or the amount of SP in the female reproductive tract after mating. Additionally, the amount of SP retained in the female did not influence egg laying. These finding suggests that additional factors, such as variation in other Acps, are important for the retention of SP in females and its quantitative effects on egg laying. It also shows that egg laying and refractory period response to SP is at least partially uncoupled.
Abstract.
Author URL.
Rostant WG, Wedell N, Hosken DJ (2012). Transposable elements and insecticide resistance.
,
78, 169-201.
Abstract:
Transposable elements and insecticide resistance
Transposable elements (TEs) are mobile DNA sequences that are able to copy themselves within a host genome. They were initially characterized as selfish genes because of documented or presumed costs to host fitness, but it has become increasingly clear that not all TEs reduce host fitness. A good example of TEs benefiting hosts is seen with insecticide resistance, where in a number of cases, TE insertions near specific genes confer resistance to these man-made products. This is particularly true of Accord and associated TEs in Drosophila melanogaster and Doc insertions in Drosophila simulans. The first of these insertions also has sexually antagonistic fitness effects in the absence of insecticides, and although the magnitude of this effect depends on the genetic background in which Accord finds itself, this represents an excellent example of intralocus sexual conflict where the precise allele involved is well characterized. We discuss this finding and the role of TEs in insecticide resistance. We also highlight areas for further research, including the need for surveys of the prevalence and fitness consequences of the Doc insertion and how Drosophila can be used as models to investigate resistance in pest species. © 2012 Elsevier Inc.
Abstract.
Rostant WG, Wedell N, Hosken DJ (2012). Transposable elements and insecticide resistance.
Adv Genet,
78, 169-201.
Abstract:
Transposable elements and insecticide resistance.
Transposable elements (TEs) are mobile DNA sequences that are able to copy themselves within a host genome. They were initially characterized as selfish genes because of documented or presumed costs to host fitness, but it has become increasingly clear that not all TEs reduce host fitness. A good example of TEs benefiting hosts is seen with insecticide resistance, where in a number of cases, TE insertions near specific genes confer resistance to these man-made products. This is particularly true of Accord and associated TEs in Drosophila melanogaster and Doc insertions in Drosophila simulans. The first of these insertions also has sexually antagonistic fitness effects in the absence of insecticides, and although the magnitude of this effect depends on the genetic background in which Accord finds itself, this represents an excellent example of intralocus sexual conflict where the precise allele involved is well characterized. We discuss this finding and the role of TEs in insecticide resistance. We also highlight areas for further research, including the need for surveys of the prevalence and fitness consequences of the Doc insertion and how Drosophila can be used as models to investigate resistance in pest species.
Abstract.
Author URL.
2011
Smith DT, Hosken DJ, Rostant WG, Yeo M, Griffin RM, Bretman A, Price TAR, Ffrench-Constant RH, Wedell N (2011). DDT resistance, epistasis and male fitness in flies.
J Evol Biol,
24(6), 1351-1362.
Abstract:
DDT resistance, epistasis and male fitness in flies.
In Drosophila melanogaster, the DDT resistance allele (DDT-R) is beneficial in the presence of DDT. Interestingly, DDT-R also elevates female fitness in the absence of DDT and existed in populations before DDT use. However, DDT-R did not spread regardless of DDT-independent selective advantages in females. We ask whether sexual antagonism could explain why DDT-R did not spread before pesticide use. We tested pre- and post-copulatory male fitness correlates in two genetic backgrounds into which we backcrossed the DDT-R allele. We found costs to DDT-R that depended on the genetic background in which DDT-R was found and documented strong epistasis between genetic background and DDT-R that influenced male size. Although it remains unclear whether DDT-R is generally sexually antagonistic, or whether the fitness costs noted would be sufficient to retard the spread of DDT-R in the absence of DDT, general fitness advantages to DDT-R in the absence of DDT may be unlikely.
Abstract.
Author URL.
Lewis Z, Wedell N, Hunt J (2011). Evidence for strong intralocus sexual conflict in the Indian meal moth, Plodia interpunctella.
Evolution,
65(7), 2085-2097.
Abstract:
Evidence for strong intralocus sexual conflict in the Indian meal moth, Plodia interpunctella.
Males and females share a genome and express many shared phenotypic traits, which are often selected in opposite directions. This generates intralocus sexual conflict that may constrain trait evolution by preventing the sexes from reaching their optimal phenotype. Furthermore, if present across multiple loci, intralocus sexual conflict can result in a gender load that may diminish the benefits of sexual selection and help maintain genetic variation for fitness. Despite the importance of intralocus sexual conflict, surprisingly few empirical studies conclusively demonstrate its operation. We show that the pattern of multivariate selection acting on three sexually dimorphic life-history traits (development time, body size, and longevity) in the Indian meal moth, Plodia interpunctella, is opposing for the sexes. Moreover, we combined our estimates of selection with the additive genetic variance-covariance matrix (G) to predict the evolutionary response of the life-history traits in the sexes and showed that the angle between the vector of responses and the vector of sexually antagonistic selection was almost orthogonal at 84.70°. Thus, G biases the predicted response of life-history traits in the sexes away from the direction of sexually antagonistic selection, confirming the presence of strong intralocus sexual conflict in this species. Despite this, sexual dimorphism has evolved in all of the life-history traits examined suggesting that mechanism(s) have evolved to resolve this conflict and allow the sexes to reach their life-history optima. We argue that intralocus sexual conflict is likely to play an important role in the evolution of divergent life-history strategies between the sexes in this species.
Abstract.
Author URL.
Price TAR, Lewis Z, Smith DT, Hurst GDD, Wedell N (2011). No evidence of mate discrimination against males carrying a sex ratio distorter in Drosophila pseudoobscura. Behavioral Ecology and Sociobiology, 1-8.
Price TAR, Lewis Z, Smith DT, Hurst GDD, Wedell N (2011). Remating in the laboratory reflects rates of polyandry in the wild.
Animal Behaviour,
82(6), 1381-1386.
Abstract:
Remating in the laboratory reflects rates of polyandry in the wild
Much of our understanding of female mating behaviour in insects comes from studies performed under controlled laboratory conditions, with Drosophila as the most commonly used model system. Laboratory studies of Drosophila have demonstrated a strong genetic basis to female remating rate. Because behaviour is strongly influenced by the environment, the heritability of remating rate in laboratory cultures does not necessarily reflect variation that is relevant to field conditions. In this study, we investigated the strength of the link between the behaviour of flies in laboratory and field. Wild-caught female Drosophila pseudoobscura that produced broods sired by multiple males had daughters that remated more rapidly in the laboratory. This suggests that laboratory experiments can successfully reflect differences between females' mating behaviour in nature. © 2011 the Association for the Study of Animal Behaviour.
Abstract.
Mank JE, Hosken DJ, Wedell N (2011). Some inconvenient truths about sex chromosome dosage compensation and the potential role of sexual conflict.
Evolution,
65(8), 2133-2144.
Abstract:
Some inconvenient truths about sex chromosome dosage compensation and the potential role of sexual conflict.
Sex chromosome dosage compensation was once thought to be required to balance gene expression levels between sex-linked and autosomal genes in the heterogametic sex. Recent evidence from a range of animals has indicated that although sex chromosome dosage compensation exists in some clades, it is far from a necessary companion to sex chromosome evolution, and is in fact rather rare in animals. This raises questions about why complex dosage compensation mechanisms arise in some clades when they are not strictly needed, and suggests that the role of sex-specific selection in sex chromosome gene regulation should be reassessed. We show there exists a tremendous diversity in the mechanisms that regulate gene dosage and argue that sexual conflict may be an overlooked agent responsible for some of the variation seen in sex chromosome gene dose regulation.
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Author URL.
Lewis Z, Champion de Crespigny FE, Sait SM, Tregenza T, Wedell N (2011). Wolbachia infection lowers fertile sperm transfer in a moth.
Biol Lett,
7(2), 187-189.
Abstract:
Wolbachia infection lowers fertile sperm transfer in a moth.
The endosymbiotic bacterium Wolbachia pipientis manipulates host reproduction by rendering infected males reproductively incompatible with uninfected females (cytoplasmic incompatibility; CI). CI is believed to occur as a result of Wolbachia-induced modifications to sperm during maturation, which prevent infected sperm from initiating successful zygote development when fertilizing uninfected females' eggs. However, the mechanism by which CI occurs has been little studied outside the genus Drosophila. Here, we show that in the sperm heteromorphic Mediterranean flour moth, Ephestia kuehniella, infected males transfer fewer fertile sperm at mating than uninfected males. In contrast, non-fertile apyrene sperm are not affected. This indicates that Wolbachia may only affect fertile sperm production and highlights the potential of the Lepidoptera as a model for examining the mechanism by which Wolbachia induces CI in insects.
Abstract.
Author URL.
2010
Taylor ML, Wedell N, Hosken DJ (2010). Attractive males do not sire superior daughters.
Evolutionary Ecology,
24(1), 195-205.
Abstract:
Attractive males do not sire superior daughters
Much of the recent work on the evolution of female choice has focused on the relative influence of direct and indirect benefits, and particularly whether direct costs can be offset by indirect benefits. Studies investigating whether attractive males benefit females by increasing the viability of their offspring often report mating advantages to sons consistent with the Fisher process, while detecting no or weak viability benefits. One potential reason for this is that sons may trade-off viability benefits with investment in costly traits that enhance mating success, leading to the suggestion that viability benefits may be better detected by examining daughters' fitness. Here we investigate the relationship between male attractiveness and daughters' fitness in Drosophila simulans. We measured daughter (and dam) lifetime reproductive success and longevity. We found no evidence that attractive males sire high fitness daughters. Additionally, neither daughters nor dams gained direct benefits from mating with attractive males. However, aspects of daughters' fitness were related to dam characters. © Springer Science+Business Media B.V. 2009.
Abstract.
Narraway C, Hunt J, Wedell N, Hosken DJ (2010). Genotype by envirnment interactions for female preference. Journal of Evolutionary Biology, 23, 2550-2557.
Ingleby FC, Lewis Z, Wedell N (2010). Level of sperm competition promotes evolution of male ejaculate allocation patterns in a moth.
ANIMAL BEHAVIOUR,
80(1), 37-43.
Author URL.
Price TAR, Hurst GDD, Wedell N (2010). Polyandry prevents extinction.
Curr Biol,
20(5), 471-475.
Abstract:
Polyandry prevents extinction.
Females of most animal species are polyandrous, with individual females usually mating with more than one male. However, the ubiquity of polyandry remains enigmatic because of the potentially high costs to females of multiple mating. Current theory to account for the high prevalence of polyandry largely focuses on its benefits to individual females. There are also higher-level explanations for the high incidence of polyandry-polyandrous clades may speciate more rapidly. Here we test the hypothesis that polyandry may also reduce population extinction risk. We demonstrate that mating with multiple males protects populations of the fruit fly Drosophila pseudoobscura against extinction caused by a "selfish" sex-ratio-distorting element. Thus, the frequency of female multiple mating in nature may be associated not only with individual benefits to females of this behavior but also with increased persistence over time of polyandrous species and populations. Furthermore, we show that female remating behavior can determine the frequency of sex-ratio distorters in populations. This may also be true for many other selfish genetic elements in natural populations.
Abstract.
Author URL.
Price TAR, Lewis Z, Smith DT, Hurst GDD, Wedell N (2010). Sex ratio drive promotes sexual conflict and sexual coevolution in the fly Drosophila pseudoobscura.
Evolution,
64(5), 1504-1509.
Abstract:
Sex ratio drive promotes sexual conflict and sexual coevolution in the fly Drosophila pseudoobscura.
Selfish genetic elements occur in all living organisms and often cause reduced fertility and sperm competitive ability in males. In the fruit fly Drosophila pseudoobscura, the presence of a sex-ratio distorting X-chromosome meiotic driver Sex Ratio (SR) has been shown to promote the evolution of increased female remating rates in laboratory populations. This is favored because it promotes sperm competition, which decreases the risk to females of producing highly female-biased broods and to their offspring of inheriting the selfish gene. Here, we show that non-SR males in these SR populations evolved an increased ability to suppress female remating in response to the higher female remating rates, indicating male-female coevolution. This occurred even though SR was rare in the populations. This was further supported by a correlation between females' remating propensity and males' ability to suppress female remating across populations. Thus SR can generate sexual conflict over female remating rate between females and the noncarrier males that make up the majority of the males, promoting evolution of increased ability of males to suppress female remating.
Abstract.
Author URL.
Lewis Z, Brakefield PM, Wedell N (2010). Speed or sperm: a potential trade-off between development and reproduction in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae).
European Journal of Entomology,
107(1), 55-59.
Abstract:
Speed or sperm: a potential trade-off between development and reproduction in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae)
Life-history theory predicts trade-offs between resources invested in reproduction and other fitness-related traits. To date, most studies have focused on potential reproductive trade-offs in females. However, it is now generally accepted that reproduction is also costly for males, and thus males too may be subject to trade-offs. We examined the relationship between development time and the production of both fertile and non-fertile sperm in males of the African bush brown butterfly (Bicyclus anynana) selected for short or long pre-adult development time. Fast developing males ejaculated fewer non-fertile sperm on their first mating, suggesting that there could be a trade-off between ejaculate production and development time in this species. Contrary to predictions, slow developing males were smaller, produced fewer fertile sperm and took longer to mate. We discuss why this might be the case, and suggest that there may be a cost to the production of non-fertile sperm in the Lepidoptera. © 2003 Institute of Entomology.
Abstract.
Wedell N, Hosken DJ (2010). The Evolution of Primary Sexual Characters in Animals. In Leonard JL, Córdoba-Aguilar A (Eds.)
The Evolution of Primary Sexual Characters in Animals, Oxford Univ Pr, 307-331.
Abstract:
The Evolution of Primary Sexual Characters in Animals
Abstract.
Wedell N (2010). Variation in male courtship costs in butterflies.
Behavioral Ecology and Sociobiology,
64(9), 1385-1391.
Abstract:
Variation in male courtship costs in butterflies
A cost of mating is common to both sexes but has predominantly been examined in females. In species where males provide resources to females at copulation, male mating costs are expected to be high as nutrient provisioning enhancing female fecundity is assumed to carry costs. In addition, males frequently court females prior to mating, which is known to carry survival costs to both sexes. However, the magnitude and basis of variation in males' mating costs remains largely unknown. Here, I examine the effect of nutrient provisioning and courtship on male longevity across full-sib families in the paternally investing green-veined white butterfly, Pieris napi. Copulating males suffered a survival cost as did courting males prevented from copulating, indicating the courtship component of mating is costly. Male P. napi release aphrodisiacs during courtship to promote mating, indicating that these compounds may also be costly to produce. Contrary to expectation, nutrient provisioning was not associated with reduced survival relative to males only allowed to court females, although it is possible that this could be masked by the potentially elevated courtship rates of courting males relative to mating males. Families differed in magnitude of reduced male survivorship, indicating a likely genetic basis to variation in costs of courtship and copulation. Male weight was unrelated to longevity and mating success, whereas longevity strongly influenced male mating success, indicating lifespan is an important male fitness trait in this species. © 2010 Springer-Verlag.
Abstract.
2009
Wedell N, Wiklund C, Bergström J (2009). Coevolution of non-fertile sperm and female receptivity in a butterfly.
Biol Lett,
5(5), 678-681.
Abstract:
Coevolution of non-fertile sperm and female receptivity in a butterfly.
Sexual conflict can promote rapid evolution of male and female reproductive traits. Males of many polyandrous butterflies transfer nutrients at mating that enhances female fecundity, but generates sexual conflict over female remating due to sperm competition. Butterflies produce both normal fertilizing sperm and large numbers of non-fertile sperm. In the green-veined white butterfly, Pieris napi, non-fertile sperm fill the females' sperm storage organ, switching off receptivity and thereby reducing female remating. There is genetic variation in the number of non-fertile sperm stored, which directly relates to the female's refractory period. There is also genetic variation in males' sperm production. Here, we show that females' refractory period and males' sperm production are genetically correlated using quantitative genetic and selection experiments. Thus selection on male manipulation may increase the frequency of susceptible females to such manipulations as a correlated response and vice versa.
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Lewis Z, Wedell N (2009). Male moths reduce sperm investment in relatives.
Animal Behaviour,
77(6), 1547-1550.
Abstract:
Male moths reduce sperm investment in relatives
Sperm production carries costs and males frequently tailor their ejaculates to maximize their reproductive success. Previous work shows that males are sensitive to variation in female quality, and to the risk and intensity of sperm competition, and adjust their ejaculates accordingly. Males and females of many species are sensitive to the relatedness of their mating partners and may forego mating with related individuals altogether to avoid the costs of inbreeding. In addition, in polyandrous species, females can potentially invoke postcopulatory mechanisms to avoid using related males' sperm, but to date no study has demonstrated that males also discriminate against related females at the level of the gamete. In this study on the Indian meal moth, Plodia interpunctella, males provided unrelated females with more fertile and nonfertile sperm than their sisters. These results indicate that male moths can minimize the potential costs of inbreeding by carefully managing their limited sperm supplies in relation to partner relatedness. © 2009 the Association for the Study of Animal Behaviour.
Abstract.
Hosken DJ, Stockley P, Tregenza T, Wedell N (2009). Monogamy and the battle of the sexes.
Annu Rev Entomol,
54, 361-378.
Abstract:
Monogamy and the battle of the sexes.
Sexual conflict has been suggested to be important in the evolution of reproductive traits, with much recent theoretical and empirical evidence emphasizing its role in generating sexually antagonistic coevolution in the context of promiscuous mating. Here we shift attention to the role of sexual conflict in a monogamous mating context. Conflicts can arise, for example, when males are successful in imposing monandry at a cost to female fitness, or when females impose monogyny on males. Conflict over remating can also generate monogamy. For example, when males invest heavily in attempting to impose female monandry, the cost of their investment may prevent them from securing additional mates. We emphasize that sexual conflicts need not always generate sexually antagonistic coevolution, and that it is important to consider whether mating decisions are controlled primarily by males or females. Finally, we briefly discuss approaches to distinguish between conflict and classical modes of sexual selection, as this highlights difficulties associated with deciding whether monogamy is enforced by one sex or the other. We suggest that documenting the current fitness consequences of mate choice and mating patterns provides insight into the relative importance of classic and conflict modes of selection.
Abstract.
Author URL.
Higgins SL, Hosken DJ, Wedell N (2009). Phenotypic and genetic variation in male genitalia in the seedbug, Lygaeus equestris (Heteroptera).
Biological Journal of the Linnean Society,
98(2), 400-405.
Abstract:
Phenotypic and genetic variation in male genitalia in the seedbug, Lygaeus equestris (Heteroptera)
Male genitalia evolve through sexual selection and, in insects, tend to show negative static allometry, low phenotypic variation, and are usually relatively small. Much less is known about the genetic variation and heritability of male genitalia. Additionally, in instances where the intromittent organ is greatly elongated, it is unclear whether typical patterns of genital scaling and variation also apply. In the present study, we investigated the allometry, variation, and heritability of male genital length in the seedbug, Lygaeus equestris, a species with a greatly elongated intromittent organ (i.e. almost as long as male body size). We found that genital length was negatively allometric, in spite of its great length, and was no more variable than nongenital traits. Additionally, genital length was significantly heritable and had considerable evolvability. © 2009 the Linnean Society of London.
Abstract.
Hornett EA, Charlat S, Wedell N, Jiggins CD, Hurst GDD (2009). Rapidly Shifting Sex Ratio across a Species Range.
Current Biology,
19(19), 1628-1631.
Abstract:
Rapidly Shifting Sex Ratio across a Species Range
Sex ratios are subject to distortion by a range of inherited parasites [1]. Although it has been predicted that the presence of these elements will result in spatial and temporal variation in host sex ratio [2-4], testing of this hypothesis has been constrained by availability of historical data. We here determine spatial and temporal variation in sex ratio in a interaction between a butterfly and male-killing Wolbachia bacteria [5] by assaying infection presence in museum specimens, and from this inferring infection prevalence and phenotype in historical populations. Comparison of contemporary and museum samples revealed profound change in four of five populations examined. Two populations become extremely female biased, associated with spread of the male-killer bacterium. One evolved from extremely female biased to a sex ratio near parity, resulting from the infection losing male-killing activity. The final population fluctuated widely in sex ratio, associated with varying frequency of the male killer. We conclude that asynchronous invasion and decline of sex-ratio distorters combines with the evolution of host suppressors to produce a rapidly changing mosaic of sex ratio. As a consequence, the reproductive ecology of the host species is likely to be fundamentally altered over short time scales [6]. Further, the study demonstrates the utility of museum specimens as "silent witnesses" of evolutionary change. © 2009 Elsevier Ltd. All rights reserved.
Abstract.
Wedell N (2009). Sperm Competition. In (Ed)
Encyclopedia of Animal Behavior, 322-328.
Abstract:
Sperm Competition
Abstract.
Price T, Lewis Z, Wedell N (2009). Sperm dumping as a defense against meiotic drive.
J Biol,
8(1).
Abstract:
Sperm dumping as a defense against meiotic drive.
Sperm from Drosophila simulans that carry a sex-ratio distorter is preferentially lost from females' sperm-storage organs. This suggests that sperm dumping is a major factor affecting sperm competition in this species, and may have evolved in response to sex-ratio distorters.
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Charlat S, Duplouy A, Hornett EA, Dyson EA, Davies N, Roderick GK, Wedell N, Hurst GD (2009). The joint evolutionary histories of Wolbachia and mitochondria in Hypolimnas bolina.
BMC Evolutionary Biology,
9(1).
Abstract:
The joint evolutionary histories of Wolbachia and mitochondria in Hypolimnas bolina
Background. The interaction between the Blue Moon butterfly, Hypolimnas bolina, and Wolbachia has attracted interest because of the high prevalence of male-killing achieved within the species, the ecological consequences of this high prevalence, the intensity of selection on the host to suppress the infection, and the presence of multiple Wolbachia infections inducing different phenotypes. We examined diversity in the co-inherited marker, mtDNA, and the partitioning of this between individuals of different infection status, as a means to investigate the population biology and evolutionary history of the Wolbachia infections. Results. Part of the mitochondrial COI gene was sequenced from 298 individuals of known infection status revealing ten different haplotypes. Despite very strong biological evidence that the sample represents a single species, the ten haplotypes did not fall within a monophyletic clade within the Hypolimnas genus, with one haplotype differing by 5% from the other nine. There were strong associations between infection status and mtDNA haplotype. The presence of wBol1 infection in association with strongly divergent haplotypes prompted closer examination of wBol1 genetic variation. This revealed the existence of two cryptic subtypes, wBol1a and wBol1b. The wBol1a infection, by far the most common, was in strict association with the single divergent mtDNA haplotype. The wBol1b infection was found with two haplotypes that were also observed in uninfected specimens. Finally, the wBol2 infection was associated with a large diversity of mtDNA haplotypes, most often shared with uninfected sympatric butterflies. Conclusion. This data overall supports the hypothesis that high prevalence of male-killing Wolbachia (wBol1) in H. bolina is associated with very high transmission efficiency rather than regular horizontal transmission. It also suggests this infection has undergone a recent selective sweep and was introduced in this species through introgression. In contrast, the sharing of haplotypes between wBol2-infected and uninfected individuals indicates that this strain is not perfectly transmitted and/or shows a significant level of horizontal transmission.
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Smith DT, Hosken DJ, Ffrench-Constant RH, Wedell N (2009). Variation in sex peptide expression in D. melanogaster.
Genet Res (Camb),
91(4), 237-242.
Abstract:
Variation in sex peptide expression in D. melanogaster.
Male Drosophila melanogaster transfers many accessory-gland proteins to females during copulation. Sex peptide (SP) is one of these and one of its main effects is to decrease female remating propensity. To date, there has been no investigation of genetic variation in SP-gene expression levels, or if such potential variation directly influences female remating behaviour. We assessed both these possibilities and found significant variation in expression levels of the SP gene across D. melanogaster isolines. A non-linear association between SP expression levels and female remating delay suggestive of disruptive selection on expression levels was also documented. Finally, while some isolines were infected with the endosymbiont Wolbachia, no association between Wolbachia and SP expression level was found.
Abstract.
Author URL.
2008
Avent TD, Price TAR, Wedell N (2008). Age-based female preference in the fruit fly Drosophila pseudoobscura.
Animal Behaviour,
75(4), 1413-1421.
Abstract:
Age-based female preference in the fruit fly Drosophila pseudoobscura
With respect to mate choice, females of many species discriminate between males on the basis of age. The adaptive significance of age-based mate choice is unclear, with various hypotheses making conflicting predictions. We examined the possibility of female preference in the fruit fly Drosophila pseudoobscura, a species where females gain no significant nutritional benefits from mating. Females were shown to prefer to mate with old males in two-male choice experiments and accepted old males faster than young males in single-male tests. Females mated to old males had a higher fecundity, possibly related to a transfer of more sperm and/or a larger volume of accessory gland proteins during the longer copulation durations experienced with old males, although these possibilities were not directly tested. Hence, females appear to derive direct benefits from preferring to mate with older males. In contrast, there was no evidence of mate preference for the sons of either old or young males when matched for age, indicating that the mating advantage of old males is not passed to their sons. These sets of experiments suggest that in D. pseudoobscura the benefit of age-based preference to females is increased fecundity due to greater investment per mating by older males. © 2007 the Association for the Study of Animal Behaviour.
Abstract.
Fischer K, Zimmer K, Wedell N (2008). Correlated responses to selection on female egg size in male reproductive traits in a butterfly\r. Evolutionary Ecology, 23, 389-402.
Champion de Crespigny, F.E. Hurst, L.D. & Wedell, N (2008). Do Wolbachia associated incompatibilities promote polyandry?\r. Evolution, 62, 107-122.
Price, T.A.R. Wedell, N. (2008). Evidence of age-based mate preference in the fly Drosophila pseudoobscura\r. Animal Behaviour
Snook RR, Chapman T, Moore PJ, Wedell N, Crudgington HS (2008). Interactions between the sexes: neglected perspectives on sexual selection and reproductive isolation. Evolutionary Ecology
Wedell N, Tregenza T, Simmons LW (2008). Nuptial gifts fail to resolve a sexual conflict in an insect.
BMC Evol Biol,
8Abstract:
Nuptial gifts fail to resolve a sexual conflict in an insect.
BACKGROUND: Because of the potential benefits to individuals of saving investment for future mating opportunities, there is conflict between mates over most aspects of reproduction. Males of many species transfer compounds in the ejaculate that manipulate female reproductive physiology to increase male reproductive success. These seminal compounds are often associated with direct and/or indirect costs to females. In contrast, in some species ejaculates also contain nutrients used by females for somatic maintenance and increased reproductive output. In general, the extent to which male seminal components are detrimental or beneficial to females is poorly understood, and interactions between seminal compounds with different effects have been almost completely neglected. Here we examine the impact of male receptivity-suppressing factors and nutrient donations on female longevity and lifetime reproductive output in the bushcricket Requena verticalis. RESULTS: We show that receiving multiple ejaculates reduces longevity in female R. verticalis, indicating a cost of male derived receptivity-suppressing compounds. Consumption of male nutrient donations does not appear to ameliorate this longevity cost, and there was no effect of nutrient provisioning on female lifetime fecundity. CONCLUSION: These results indicate that nutrient provisioning does not provide a resolution to sexual conflict over female receptivity in this bushcricket species.
Abstract.
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Wedell, N. (2008). Selfish genetic elements and sexual selection: their impact on male fertility\r. Genetica, 132, 295-307.
Price TAR, Hodgson DJ, Lewis Z, Hurst GDD, Wedell N (2008). Selfish genetic elements promote polyandry in a fly.
Science,
322(5905), 1241-1243.
Abstract:
Selfish genetic elements promote polyandry in a fly.
It is unknown why females mate with multiple males when mating is frequently costly and a single copulation often provides enough sperm to fertilize all a female's eggs. One possibility is that remating increases the fitness of offspring, because fertilization success is biased toward the sperm of high-fitness males. We show that female Drosophila pseudoobscura evolved increased remating rates when exposed to the risk of mating with males carrying a deleterious sex ratio-distorting gene that also reduces sperm competitive ability. Because selfish genetic elements that reduce sperm competitive ability are generally associated with low genetic fitness, they may represent a common driver of the evolution of polyandry.
Abstract.
Author URL.
Price TAR, Bretman AJ, Avent TD, Snook RR, Hurst GDD, Wedell N (2008). Sex ratio distorter reduces sperm competitive ability in an insect.
Evolution,
62(7), 1644-1652.
Abstract:
Sex ratio distorter reduces sperm competitive ability in an insect.
Selfish genetic elements (SGEs) are ubiquitous in animals and often associated with low male fertility due to reduced sperm number in male carriers. In the fruit fly Drosophila pseudoobscura, the meiotic driving X chromosome "sex ratio" kills Y-bearing sperm in carrier males (SR males), resulting in female only broods. We competed SR males against the ejaculates of noncarrying standard males (ST males), and quantified the number of sperm transferred by SR and ST males to females. We show that SR males are very poor sperm competitors, which is partly related to transfer of fewer sperm during mating. However, sperm numbers alone cannot explain the observed paternity reduction, indicating SR males' sperm may be of reduced quality, possibly due to damage during the killing of the noncarrying Y-sperm. The reduction in sperm competitive ability due to SR is large enough to potentially stabilize the spread of sex ratio drive through populations. The poor sperm competitive ability of SR males coupled with their low fitness as mates could favor increased remating by females to reduce paternity by SR males. Given the generally poor performance of SGE-carrying males in sperm competition, this may generate strong selective pressure favoring polyandry in many species.
Abstract.
Author URL.
Taylor ML, Wedell, N. Hosken, D.J. (2008). Sexual selection and female fitness in <em>Drosophila simulans</em>. Behavioral Ecology and Sociobiology, 62, 721-728.
Chapman, T. Moore, P.J. Wedell, N. (2008). Sexual selection and reproductive isolation. Evolutionary Ecology
Lewis Z, Price TAR, Wedell N (2008). Sperm competition, immunity, selfish genes and cancer.
Cellular and Molecular Life Sciences,
65(20), 3241-3254.
Abstract:
Sperm competition, immunity, selfish genes and cancer
Sperm competition is widespread and has played an important role in shaping male reproductive characters such as testis size and numbers of sperm produced, and this is reflected in the rapid evolution of many reproductive genes. Additionally, sperm competition has been implicated in the rapid evolution of seminal fluids. However, our understanding of the molecular basis of many traits thought to be important in sperm competition is rudimentary. Furthermore, links between sperm competition and a range of issues not directly related to reproduction are only just beginning to be explored. These include associations between sperm competition and selfish genes, immunity and diseases such as cancer.We briefly review these topics and suggest areas we consider worthy of additional research. © 2008 Birkhaueser.
Abstract.
Champion De Crespigny FE, Wedell N (2008). The impact of anaesthetic technique on survival and fertility in Drosophila.
Physiological Entomology,
33(4), 310-315.
Abstract:
The impact of anaesthetic technique on survival and fertility in Drosophila
The consequences of ice and carbon dioxide anaesthetics on the survival and reproductive success of Drosophila simulans and Drosophila melanogaster were investigated after observations of high levels of mortality in D. simulans, possibly associated with brief chill coma. The association between brief chill coma and death is confirmed in female D. simulans but there is no mortality in male D. simulans or D. melanogaster of either sex. Mortality is unlikely to be associated with a strain specific cold intolerance because two geographically distinct populations of D. simulans were examined. In addition to the effect of ice anaesthesia, anaesthetizing newly-eclosed male D. simulans with CO 2 causes a reduction in fertility, which is evident 9-13 days after anaesthesia. This finding is important given that CO2 anaesthesia is a standard technique used in Drosophila and other insect cultures, and may have important consequences for studies of male fertility and sperm competition. © 2008 the Authors.
Abstract.
Hornett EA, Duplouy AMR, Davies N, Roderick GK, Wedell N, Hurst GDD, Charlat S (2008). You can't keep a good parasite down: Evolution of a male-killer suppressor uncovers cytoplasmic incompatibility.
Evolution,
62(5), 1258-1263.
Abstract:
You can't keep a good parasite down: Evolution of a male-killer suppressor uncovers cytoplasmic incompatibility
Maternally inherited parasites are known to impose a wide variety of reproductive manipulations upon their host. These often produce strong selection on the host to suppress the parasite, resulting in a reduction in the frequency of the parasite. However, in the butterfly Hypolimnas bolina, infected with a Wolbachia bacterium, field data demonstrate that suppression of the male-killing phenotype does not depress parasite frequency. Here we test and verify one hypothesis to explain this apparent paradox - Wolbachia induces a second phenotype, Cytoplasmic Incompatibility (CI), in populations where host suppression has evolved. We further demonstrate that the capacity to induce CI has not evolved de novo, but instead is instantaneously expressed upon the survival of infected males. The significance of these results is threefold: (1) multiple phenotypes can provide Wolbachia with the means to maintain itself in a host following suppression of a single manipulative phenotype; (2) the ability to induce CI can remain hidden in systems in which male-killing is observed, just as the ability to induce male-killing may be obscured in strains exhibiting CI; (3) the evolutionary maintenance of CI in a system in which it is not expressed suggests a functional link with male-killing or other traits under selection. © 2008 the Author(s).
Abstract.
2007
Wedell, N. (2007). Effect of adult feeding on ejaculate production in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae).\r. Journal of Insect Behaviour, 20, 201-213.
Lewis Z, Wedell N (2007). Effect of adult feeding on male mating behaviour in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae).
Journal of Insect Behavior,
20(2), 201-213.
Abstract:
Effect of adult feeding on male mating behaviour in the butterfly, Bicyclus anynana (Lepidoptera: Nymphalidae)
Many species of lepidopterans supplement their nectar diet with foods rich in nitrogen and minerals, which are present only in trace amounts in nectar. We examined the effect of adult diet on mating behaviour and spermatophore characteristics in male Bicyclus anynana (Butler, 1879) butterflies, which feed on rotten fruits as adults. We found little effect of adult diet on male reproduction in terms of mating rate and sperm production, although males fed on fruit produced larger spermatophores on their first mating compared to males fed sugar only. We also examined how males allocate sperm across matings. Males ejaculate larger spermatophores during their first mating, and produce spermatophores containing decreasingly fewer non-fertile sperm with number of matings performed. Males that produced more non-fertile sperm on their first mating had reduced lifespan possibly indicating a trade-off between sperm production and adult longevity. It is suggested that adult diet has little affect on male ejaculate production and males feed on fruit to supplement their energetic carbon requirements. © 2007 Springer Science+Business Media, LLC.
Abstract.
Hornett, E.A. Fullard, J.H. Davies, N. (2007). Extraordinary flux in sex-ratio. Science, 317: 214
Charlat S, Reuter M, Dyson EA, Hornett EA, Duplouy A, Davies N, Roderick GK, Wedell N, Hurst GDD (2007). Male-Killing Bacteria Trigger a Cycle of Increasing Male Fatigue and Female Promiscuity.
Current Biology,
17(3), 273-277.
Abstract:
Male-Killing Bacteria Trigger a Cycle of Increasing Male Fatigue and Female Promiscuity
Sex-ratio distorters are found in numerous species and can reach high frequencies within populations. Here, we address the compelling, but poorly tested, hypothesis that the sex ratio bias caused by such elements profoundly alters their host's mating system. We compare aspects of female and male reproductive biology between island populations of the butterfly Hypolimnas bolina that show varying degrees of female bias, because of a male-killing Wolbachia infection. Contrary to expectation, female bias leads to an increase in female mating frequency, up to a point where male mating capacity becomes limiting. We show that increased female mating frequency can be explained as a facultative response to the depleted male mating resources in female biased populations. In other words, this system is one where male-killing bacteria trigger a vicious circle of increasing male fatigue and female promiscuity. © 2007 Elsevier Ltd. All rights reserved.
Abstract.
Rueter, M. Dyson, E.A. Hornett, E.A. (2007). Male-killing bacteria increase female mating frequency. Current Biology, 17: 273-277
Champion De Crespigny FE, Wedell N (2007). Mate preferences in Drosophila infected with Wolbachia?.
Behavioral Ecology and Sociobiology,
61(8), 1229-1235.
Abstract:
Mate preferences in Drosophila infected with Wolbachia?
The maternally inherited bacterium Wolbachia pipientis generates strong reproductive incompatibilities between uninfected females and infected males (cytoplasmic incompatibility), significantly reducing both female and male reproductive success. Such fitness costs are thought to place selective pressure on hosts to evolve pre-copulatory preferences for mating with compatible mates, thereby enabling them to avoid the reproductive incompatibilities associated with Wolbachia. Therefore, uninfected females are predicted to prefer mating with uninfected males, whereas infected males are predicted to prefer mating with infected females. Despite these predictions, previous investigations of pre-copulatory mate preferences in Wolbachia-manipulated Drosophila have not found evidence of female preference for uninfected or compatible males. However, none of these studies utilised a design where focal individuals are provided with a simple choice in a relatively non-competitive situation. We examined both female and male pre-copulatory mate preference based on mate infection status in Drosophila simulans and D. melanogaster using simple choice assays involving between 30-50 replicates per treatment. Although we found no evidence of female pre-copulatory mate preferences in either species, male D. simulans exhibited some preference for mating with females of the same infection status. However, this preference was not evident when we repeated the experiment to confirm this finding. Consequently, we conclude that neither male nor female D. melanogaster and D. simulans exhibit significant Wolbachia-associated pre-copulatory mate preferences. © 2007 Springer-Verlag.
Abstract.
Champion de Crespigny, F.E. & Wedell, N (2007). Mate preferences in Wolbachia infected Drosophila\r. Behavioral Ecology and Sociobiology, 61, 1229-1235.
Wedell, N. (2007). Selfish genetic elements and sexual selection: their impact on male fertility. Genetica
Wedell, N. (2007). Sperm competition and ejaculate evolution. In Roldan E, Gomendio M (Eds.) Spermatology, 115-135.
Wedell N (2007). Sperm competition and ejaculate evolution.
Soc Reprod Fertil Suppl,
65, 115-135.
Abstract:
Sperm competition and ejaculate evolution.
Under sperm competition, production of large numbers of sperm is often advantageous, either due to numerical superiority or by displacing a larger volume of rival sperm. However, sperm and ejaculate production are inevitably associated with costs, which at times can directly limit male mating rates. As a consequence of sperm limitation, males are expected to strategically allocate their ejaculates to maximise fertilisations. Here I review the evidence for sperm production costs and male ejaculate tailoring showing that males are sensitive to cues relating to varying levels of sperm competition and female fecundity and modulate their ejaculates accordingly. Variation in ejaculation production costs are also shown to influence male ejaculates in relation to outbreeding, cost of inbreeding, and reproductive parasites. There is evidence that females suffer reduced fertility as a consequence of male strategic ejaculation, potentially resulting in sexual conflict over number of sperm delivered. The cost of ejaculate production and the necessity of producing large quantities of sperm may have promoted the evolution of 'manipulative' ejaculates, (e.g. mating plugs, non-fertile sperm, cooperative sperm, and seminal peptides). Many of these ejaculate components are designed to reduce or remove the risk of sperm competition altogether and hence the need to transfer large numbers or elaborate sperm to the female. Some of these adaptations are costly to females since they interfere with their reproductive rate or physiology.
Abstract.
Author URL.
Hurst G, Charlat S, Hornett E, Wedell N (2007). Survival of the fastest.
Planet Earth(AUTUMN).
Abstract:
Survival of the fastest
In some species, the sex ration can be biased towards daughters by the action of inherited parasites and in the case of the Hypolimnas bolina butterfly in Polynesia, the parasite is known as the Wolbachia bacteria. The male-killing bacterium is no longer a male-killer as was observed 30 years ago due to evolution. A gene that suppresses the action of the male-killer is now featured in the butterfly. The trend is different in other islands, though, as as recently as 2001, the ratio of female to male is 1:100.
Abstract.
Taylor, M, Wedell, N. Hosken, D.J. (2007). The heritability of attractiveness. Current Biology, 17, R959-R960.
2006
Dyson, E.A. Hornett, E.A. Duplouy, A.M.R. (2006). Competing selfish genetic elements in the butterfly Hypolimnas bolina. \r. Current Biology, 16, 2453-2458.
Mcnamara, J.M. Wedell, N. Hosken, D.J. (2006). Debating sexual selection and mating strategies. Science, 312
Dall SRX, McNamara JM, Wedell N, Hosken DJ (2006). Debating sexual selection and mating strategies.
Science,
312(5774), 689-697.
Author URL.
Wedell N, Charlat S, Davies N, Duploy AMR (2006). Evolution of male killer suppression in a natural population.
PLoS Biology,
4(9).
Full text.
Tregenza, T. Simmons, L.W. Wedell, N. & Zuk, M. (2006). Female preference for male courtship song and its role as a signal of immune function and condition. Animal Behaviour, 72, 809-118.
de Crespigny FEC, Pitt TD, Wedell N (2006). Increased male mating rate in Drosophila is associated with Wolbachia infection.
J Evol Biol,
19(6), 1964-1972.
Abstract:
Increased male mating rate in Drosophila is associated with Wolbachia infection.
The maternally inherited bacterium Wolbachia pipientis infects 25-75% of arthropods and manipulates host reproduction to improve its transmission. One way Wolbachia achieves this is by inducing cytoplasmic incompatibility (CI), where crosses between infected males and uninfected females are inviable. Infected males suffer reduced fertility through CI and reduced sperm production. However, Wolbachia induce lower levels of CI in nonvirgin males. We examined the impact of Wolbachia on mating behaviour in male Drosophila melanogaster and D. simulans, which display varying levels of CI, and show that infected males mate at a higher rate than uninfected males in both species. This may serve to increase the spread of Wolbachia, or alternatively, may be a behavioural adaptation employed by males to reduce the level of CI. Mating at high rate restores reproductive compatibility with uninfected females resulting in higher male reproductive success thus promoting male promiscuity. Increased male mating rates also have implications for the transmission of Wolbachia.
Abstract.
Author URL.
Tregenza T, Wedell N, Chapman T (2006). Introduction. Sexual conflict: a new paradigm?.
Philos Trans R Soc Lond B Biol Sci,
361(1466), 229-234.
Author URL.
Wedell N (2006). Male genotype affects female fitness in a paternally investing species. Evolution, 60(8), 1638-1645.
Wedell, N. Beveridge, M. Tregenza, T. (2006). Post-copulatory inbreeding avoidance by female crickets only revealed by molecular markers. Molecular Ecology, 15(12), 3817-3824.
Wedell, N. Chapman, T.C. (2006). Sexual conflict - a new paradigm?. Philosophical Transactions of the Royal Society, 361, 229-234.
Kvarnemo, L. Lessells, C.M. Tregenza (2006). Sexual conflict and life histories. Animal Behaviour, 71, 999-1011.
Andrews, T. Ingrey, H. Dunn, A. (2006). Strategic sperm allocation under parasitic sex ratio distortion. Biology Letters, 2(1), 78-80.
Wedell, N. (2006). The role of selfish genetic elements in sexual selection. Philosophical Transactions of the Royal Society B
Ballantyne, G.A. Wedell, N. (2006). Variation in the cost to females of the sexual conflict over mating in the seed bug Lygaeus equestris (Hemiptera: Lygaeidae).\r. Animal Behaviour, 72, 313-321.
Shuker DM, Ballantyne GA, Wedell N (2006). Variation in the cost to females of the sexual conflict over mating in the seed bug, Lygaeus equestris.
Animal Behaviour,
72(2), 313-321.
Abstract:
Variation in the cost to females of the sexual conflict over mating in the seed bug, Lygaeus equestris
Conflict between males and females over reproduction influences the evolution of numerous aspects of reproductive behaviour, including how frequently individuals mate. Typically, females optimize the benefits of mating with a limited number of copulations, whereas males may benefit from increasing the number of copulations, leading to a sexual conflict over female mating rate. While this conflict is theoretically straightforward, empirically much less is known about how commonly it is realized. We quantified the costs of mating for females from two populations of the promiscuous Lygaeus equestris seed bug. By varying the number of males kept with a female, we found that increased matings led to decreased longevity and fecundity, and that the detrimental effects of mating varied between the two populations. When females mated only once, male weight positively influenced egg production, as did copulation duration for lighter females, suggesting that females may benefit from mating with certain males, albeit a limited number of times. Our results show that degree of promiscuity may not be a good predictor of mating costs (i.e. how costly the sexual conflict over mating actually is) and that life history differences between populations have the potential to influence the extent to which the sexes come into conflict. © 2006 the Association for the Study of Animal Behaviour.
Abstract.
Pitt, T. Wedell, N. (2006). Wolbachia increases male mating rate in Drosophila. Journal of Evolutionary Biology, 19: 1964-1972
Wedell N, Champion de Crespigny FE (2006). Wolbachia infection reduces sperm competitive ability in an insect. Proceedings of the Royal Society B Biological Sciences, 273(1593), 1455-1458.
De Crespigny FEC, Wedell N (2006). Wolbachia infection reduces sperm competitive ability in an insect.
Proceedings of the Royal Society B: Biological Sciences,
273(1593), 1455-1458.
Abstract:
Wolbachia infection reduces sperm competitive ability in an insect
The maternally inherited bacterium Wolbachia pipientis imposes significant fitness costs on its hosts. One such cost is decreased sperm production resulting in reduced fertility of male Drosophila simulans infected with cytoplasmic incompatibility (CI) inducing Wolbachia. We tested the hypothesis that Wolbachia infection affects sperm competitive ability and found that Wolbachia infection is indeed associated with reduced success in sperm competition in non-virgin males. In the second male role, infected males sired 71% of the offspring whereas uninfected males sired 82% of offspring. This is the first empirical evidence indicating that Wolbachia infection deleteriously affects sperm competition and raises the possibility that polyandrous females can utilize differential sperm competitive ability to bias the paternity of broods and avoid the selfish manipulations of Wolbachia. This suggests a relationship between Wolbachia infection and host reproductive strategies. These findings also have important consequences for Wolbachia population dynamics because the transmission advantage of Wolbachia is likely to be undermined by sperm competition. © 2006 the Royal Society.
Abstract.
2005
Champion de Crespigny, F. E. Butlin, R. K. & Wedell, N. (2005). Can cytoplasmic incompatibility inducing Wolbachia promote the evolution of mate preferences?. \r. Journal of Evolutionary Biology, 18, 967-977.
Dall SRX, Wedell N (2005). Evolutionary conflict: sperm wars, phantom inseminations.
Curr Biol,
15(19), R801-R803.
Abstract:
Evolutionary conflict: sperm wars, phantom inseminations.
A new experimental study has provided the first definitive evidence for conditional punishment of 'cheats' in a sperm-trading simultaneous hermaphrodite: the sea slug Chelidonura hirundinina. This also provides a rare unequivocal example of conditional reciprocity averting a 'tragedy of the commons' in biology.
Abstract.
Author URL.
Dall SRX, Wedell, N. (2005). Evolutionary conflict: sperm wars, phantom inseminations. Current Biology, 19, R801-803.
Wedell, N. (2005). Female receptivity in butterflies and moths. Journal of Experimental Biology, 208: 3433-3440
Wedell, N. (2005). Sperm competition in butterflies and moths. In Fellowes MDE, Holloway GJ, Rolff J (Eds.) Insect Evolutionary Ecology, CABI Publishing, 49-81.
2004
Ritchie, M.G. (2004). Male age, mating status and nuptial gift quality in a bushcricket. \r. Animal Behaviour, 67, 1059-1065.
Bretman AJ, Wedell N, Tregenza T (2004). Molecular evidence of post-copulatory inbreeding avoidance in the field cricket Gryllus bimaculatus. Proceedings of the Royal Society B Biological Sciences, 271(1535), 159-164.
Wedell, N. Tregenza, T. (2004). Polyandry and inbreeding avoidance: Evidence from the field cricket Gryllus bimaculatus\r. Proceedings of the Royal Society B, 271, 159-164.
2003
Tregenza T, Hosken DJ, Ward PI, Wedell N (2003). Maternal effects on offspring depend on female mating pattern and offspring environment in yellow dung flies. Evolution, 57(2), 297-304.
Wedell N, Karlsson B (2003). Paternal investment directly affects female reproductive effort in an insect. Proceedings of the Royal Society B Biological Sciences, 270(1528), 2065-2071.
Hosken DJ, Garner, T.W.J. Tregenza, T. Wedell N, Ward PI (2003). Superior sperm competitors sire higher quality young. Proceedings of the Royal Society of London B, 270, 1933-1938.
2002
Ward PI, Wedell, N. Hosken, D.J. Tregenza T (2002). Measuring the sperm competition successes of field males of the yellow dung fly. Ecological Entomology, 27, 763-765.
Wedell, N. Hosken, D.J. Tregenza, T. (2002). Measuring the sperm competition successes of field males. \r. Ecological Entomology, 27, 763-765.
Wiklund, C. Cook, P.A. (2002). Monandry and polyandry as alternative lifestyles in a butterfly.\r. Behavioral Ecology, 13, 450-455.
Tregenza, T. Wedell, N. (2002). Oviposition preference and geographic specialization by the mrymecophilous butterfly <em>Jalmenus evagoras</em> (Lepidoptera: Lycaenidae) in response to attendant ants. Journal of Evolutionary Biology, 15, 861-870.
Fraser AM, Tregenza T, Wedell N, Elgar MA, Pierce NE (2002). Oviposition tests of ant preference in a myrmecophilous butterfly.
JOURNAL OF EVOLUTIONARY BIOLOGY,
15(5), 861-870.
Author URL.
Tregenza T, Wedell N (2002). Polyandrous females avoid costs of inbreeding. Nature, 415(6867), 71-73.
Gage, M.J.G. Parker, G.A. (2002). Sperm competition, male prudence and sperm limited females. Trends in Ecology & Evolution, 17: 313-320
2001
Wedell, N. (2001). Female remating in butterflies: interaction between female genotype and non-fertile sperm. Journal of Evolutionary Biology, 14, 746-754.
2000
Tregenza T, Butlin RK, Wedell N (2000). Evolutionary biology - Sexual conflict and speciation.
NATURE,
407(6801), 149-150.
Author URL.
Tregenza T, Wedell N (2000). Genetic compatibility, mate choice and patterns of parentage: invited review.
Mol Ecol,
9(8), 1013-1027.
Abstract:
Genetic compatibility, mate choice and patterns of parentage: invited review.
There is growing interest in the possibility that genetic compatibility may drive mate choice, including gamete choice, particularly from the perspective of understanding why females frequently mate with more than one male. Mate choice for compatibility differs from other forms of choice for genetic benefits (such as 'good genes') because individuals are expected to differ in their mate preferences, changing the evolutionary dynamics of sexual selection. Recent experiments designed to investigate genetic benefits of polyandry suggest that mate choice on the basis of genetic compatibility may be widespread. However, in most systems the mechanisms responsible for variation in compatibility are unknown. We review potential sources of variation in genetic compatibility and whether there is any evidence for mate choice driven by these factors. Selfish genetic elements appear to have the potential to drive mate compatibility mate choice, though as yet there is only one convincing example. There is abundant evidence for assortative mating between populations in hybrid zones, but very few examples where this is clearly a result of selection against mating with genetically less compatible individuals. There are also numerous cases of inbreeding avoidance, but little evidence that mate choice or differential fertilization success driven by genetic compatibility occurs between unrelated individuals. The exceptions to this are a handful of situations where both the alleles causing incompatibility and the alleles involved in mate choice are located in a chromosome region where recombination is suppressed. As yet there are only a few potential sources of genetic compatibility which have clearly been shown to drive mate choice. This may reflect limitations in the potential for the evolution of mate choice for genetic compatibility within populations, although the most promising sources of such incompatibilities have received relatively little research.
Abstract.
Author URL.
Tregenza T, Butlin RK, Wedell N (2000). Sexual conflict and speciation.
Nature,
407(6801), 149-150.
Author URL.
1999
Tregenza, T. (1999). Successful fathers sire successful sons. Evolution, 53, 620-625.
1998
Wedell, N. (1998). Benefits of multiple mates in the cricket <em>Gryllus bimaculatus</em>. Evolution, 52, 1726-1730.
1997
Wedell, N. (1997). Definitive evidence for cuticular pheromones in a cricket. Animal Behaviour, 54, 979-984.
Wedell, N. (1997). Natural selection bias?. Nature, 386
