Dr Bonnie Fraser

About me: The main goal of our research group is to investigate how adaptation to the local environment shapes evolution at the genomic level. The connections between genotype, phenotype, and selection are at the centre of evolutionary biology. By studying these connections, our research can begin to address fundamental questions in evolutionary biology.

Our research focuses on the Trinidadian guppy (Poecilia reticulata), a fish that has long served as a model system for evolutionary and ecological research. We explore local adaptation in this system using an interdisciplinary approach that combines population genomics, quantitative genetics, behavioural ecology, and experimental evolution.

Interests:
Local adaptation in the Trinidadian guppy

Guppies in the Northern Mountain Range of Trinidad offer a natural laboratory for studying evolutionary change and the genetics of adaptation. Waterfalls separate the rivers the guppies call home into downstream stretches, which contain many predators, and upstream stretches, where the guppies live relatively free of predation. In response to this naturally replicated environmental gradient, guppies from low predation sites have evolved to be larger and more colourful, and to display less anti-predator behaviour. We are exploring how this convergent evolution plays out at the genomic level, using a combination of population genomics, quantitative genetics, and laboratory evolution experiments.

How do populations adapt to new environments?

The simple ecology of the guppy’s home streams in Trinidad allows for in situ experimental studies of adaptation. Guppy populations that were moved from high predation to low predation sites have shown consistent and rapid evolutionary responses to reduced predation. By examining genomic differences between experimental populations and their source populations, and between experimental populations established at different time points, we hope to learn more about which types of molecular changes are important in the process of adaptation.

What maintains variation in natural populations?

Selection is expected to eliminate genetic diversity within populations. Surprisingly, guppies exhibit high within-population genetic diversity for male body colour even though it is subject to strong natural and sexual selection. Previous studies suggest that two different behavioural mechanisms might explain this unusual finding: (1) learned hunting behaviour by one of the guppy’s predators, the killifish Rivulus hartii, and (2) female mate choice for males with unfamiliar colour patterns. We are using a combination of ecological, behavioural, and genomic data to test alternative hypotheses for the role of behaviour in maintaining variation in guppy colouration, and to identify the genes targeted by behaviour-mediated selection.

Postgraduate Research opportunities:  I am open to email enquires from students with their own funding interested in pursuing an MSc by Research or PhD in evolutionary biology research. I am also open to supporting students interested in this are who would like to apply to the China Scholarship Council, Commonwealth Scholarship, or other PhD funding scheme.