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Faculty of Health and Life Sciences

Dr Cameron Weadick

Dr Cameron Weadick

Royal Society Dorothy Hodgkin Fellow


 Newman Lower Ground Floor (The Cave)


I am interested in the processes that shape biological diversity at the organismal and genetic levels. My present focus is on the consequences of relaxed natural selection—on the evolutionary fate of adaptations that are no longer critical to survival and reproduction.  When environmental conditions change, mutations that alter previously adaptive traits can accumulate, and novel selection pressures that act to reshape these traits can emerge.  The study of relaxed selection provides an important complement to adaptation-focussed research in the context of environmental change.

Environmental change can take many forms, including alterations to the social and demographic environment.  For most familiar animals, a key aspect of their environment is the number of potential reproductive partners: males and females must find or reach one another for either to achieve any reproductive success.  However, some species have abandoned this system in place of alternatives that allow for unisexual reproduction, for example self-fertile hermaphroditism.  Such mating system transitions have the potential to severely relax selection on traits involved in reproduction.  

I am using Pristionchus nematodes (roundworms) to explore how the evolution of self-fertile hermaphroditism affects selection on reproductive biology.  Several species in this group have independently evolved self-fertile hermaphroditic mating systems; these hermaphrodites are, in effect, females that have acquired the ability to produce and use their own sperm.  Reproduction via selfing rapidly causes males to become so rare that they make minimal contributions to reproduction, and it shifts the reproductive age-distribution to begin and end earlier in life.  The evolution of selfing should therefore lead to severely relaxed selection on both male biology and late-life hermaphrodite biology.

My research program will explore how mating system transitions affect evolution across the Pristionchus genus using a mixture of comparative and experimental approaches.  This work asks whether and how traits degenerate once selection has been relaxed (e.g., where and when does selection contribute to degeneration, and how repeatable is the process?).  More broadly, this work speaks to the biology of sex differences, and the evolution of senescence and disease.

I have additional interests in the development and use of phylogenetic and molecular evolutionary methods for studying protein biology, and in exploring the natural diversity of local nematodes. 


PhD - University of Toronto

BSc (honours) - University of Guelph


2018–present - Royal Society Dorothy Hodgkin Fellow, University of Exeter

2016–2018 - Family Leave

2011–2016 - Postdoctoral Research Fellow, Max Planck Institute for Developmental Biology

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Journal articles

Dong C, Weadick CJ, Truffault V, Sommer RJ (2020). Convergent evolution of small molecule pheromones in pristionchus nematodes. eLife, 9 Abstract.
Fraser BA, Whiting JR, Paris JR, Weadick CJ, Parsons PJ, Charlesworth D, Bergero R, Bemm F, Hoffmann M, Kottler VA, et al (2020). Improved Reference Genome Uncovers Novel Sex-Linked Regions in the Guppy (Poecilia reticulata). Genome Biology and Evolution, 12(10), 1789-1805. Abstract.
Weadick CJ (2020). Molecular Evolutionary Analysis of Nematode Zona Pellucida (ZP) Modules Reveals Disulfide-Bond Reshuffling and Standalone ZP-C Domains. Genome Biology and Evolution, 12(8), 1240-1255. Abstract.
Escalona T, Weadick CJ, Antunes A (2017). Adaptive Patterns of Mitogenome Evolution Are Associated with the Loss of Shell Scutes in Turtles. Molecular Biology and Evolution, 34(10), 2522-2536. Abstract.
Weadick CJ, Sommer RJ (2017). Hybrid crosses and the genetic basis of interspecific divergence in lifespan in <i>Pristionchus</i> nematodes. JOURNAL OF EVOLUTIONARY BIOLOGY, 30(3), 650-657.  Author URL.
Weadick CJ, Sommer RJ (2016). Mating System Transitions Drive Life Span Evolution in Pristionchus Nematodes. Am Nat, 187(4), 517-531. Abstract.  Author URL.
Weadick CJ, Sommer RJ (2016). Unexpected sex-specific post-reproductive lifespan in the free-living nematode Pristionchus exspectatus. Evolution and Development, 18(5-6), 297-307. Abstract.
Lin YG, Weadick CJ, Santini F, Chang BSW (2013). Molecular evolutionary analysis of vertebrate transducins: a role for amino acid variation in photoreceptor deactivation. Journal of Molecular Evolution, 77(5-6), 231-245. Abstract.
Weadick CJ, Chang BSW (2012). An improved likelihood ratio test for detecting site-specific functional divergence among clades of protein-coding genes. Molecular Biology and Evolution, 29(5), 1297-1300. Abstract.
Weadick CJ, Chang BSW (2012). Complex patterns of divergence among green-sensitive (RH2a) African cichlid opsins revealed by Clade model analyses. BMC Evolutionary Biology, 12(1). Abstract.
de Serrano AR, Weadick CJ, Price AC, Rodd FH (2012). Seeing orange: Prawns tap into a pre-existing sensory bias of the trinidadian guppy. Proceedings of the Royal Society B: Biological Sciences, 279(1741), 3321-3328. Abstract.
Weadick CJ, Loew ER, Helen Rodd F, Chang BSW (2012). Visual pigment molecular evolution in the trinidadian pike cichlid (crenicichla frenata): a less colorful world for neotropical cichlids?. Molecular Biology and Evolution, 29(10), 3045-3060. Abstract.
Fraser BA, Weadick CJ, Janowitz I, Rodd FH, Hughes KA (2011). Sequencing and characterization of the guppy (Poecilia reticulata) transcriptome. BMC Genomics, 12(1).
Wong L, Weadick CJ, Kuo C, Chang BS, Tropepe V (2010). Duplicate dmbx1 genes regulate progenitor cell cycle and differentiation during zebrafish midbrain and retinal development. BMC Developmental Biology, 10 Abstract.
Weadick CJ, Chang BSW (2009). Molecular evolution of the βγ lens crystallin superfamily: Evidence for a retained ancestral function in γn crystallins?. Molecular Biology and Evolution, 26(5), 1127-1142. Abstract.
Price AC, Weadick CJ, Shim J, Rodd FH (2008). Pigments, patterns, and fish behavior. Zebrafish, 5(4), 297-307. Abstract.
Hult EF, Weadick CJ, Chang BSW, Tobe SS (2008). Reconstruction of ancestral FGLamide-type insect allatostatins: a novel approach to the study of allatostatin function and evolution. Journal of Insect Physiology, 54(6), 959-968. Abstract.
Fu J, Weadick CJ, Bi K (2007). A phylogeny of the high-elevation Tibetan megophryid frogs and evidence for the multiple origins of reversed sexual size dimorphism. JOURNAL OF ZOOLOGY, 273(3), 315-325.  Author URL.
Fu J, Weadick CJ, Zeng X, Wang Y, Liu Z, Zheng Y, Li C, Hu Y (2005). Phylogeographic analysis of the Bufo gargarizans species complex: a revisit. Molecular Phylogenetics and Evolution, 37(1), 202-213. Abstract.


Chang BSW, Du J, Weadick CJ, Müller J, Bickelmann C, David Yu D, Morrow JM (2012). The future of codon models in studies of molecular function: Ancestral reconstruction and clade models of functional divergence. In  (Ed) Codon Evolution: Mechanisms and Models. Abstract.


Weadick CJ, Chang BSW (2007). Long-wavelength sensitive visual pigments of the guppy (Poecilia reticulata): Six opsins expressed in a single individual. Abstract.

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Office Hours:

I am currently working at 80% FTE (M, T, Th, F).

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