Selection and evolution of coat colour in a wild mammal

This project offers the opportunity to study evolutionary genetics as part of the Soay sheep project, one of the most data-rich long-term studies of any vertebrate in the world. There will be opportunities to visit and work on St Kilda, a UNESCO world heritage site.

Understanding how genetic and phenotypic variation changes in response to environmental conditions remains one of the great challenges in evolutionary biology. Ten years ago we published a paper in Science (Gratten et al. 2008) showing how allelic variation at the TYRP1 gene underlying a coat colour polymorphism in a wild Soay sheep population has been under natural selection, and how variation at TYRP1 has been maintained. In the following decade, the environment on St Kilda has changed, the population size has increased, and demographic models (conducted by co-supervisor DZC) predict a dramatic change in allele frequency dynamics.

Here the student will combine evolutionary genomics tools (SNP genetic profiling), state-of-the-art demographic modelling and ecological data to study how Soay sheep coat colour evolutionary dynamics have changed in the last decade. The findings will shed further light on the evolution and maintenance of genetic variation, and will provide a framework with which to robustly test demographic predictive models. Testing how gene frequencies change in response to real-time environmental change is not often possible in wild vertebrate populations, but the short generation time (males and females can breed at age 6 months) and long-term data set make the St Kilda Soay sheep population an exception. Since our previous publication several thousand sheep have been born and monitored throughout their lifetimes. Advances in genomics tools mean that SNP genotype data (at ~500,000 loci) are available for nearly all of them. There are very few, if any, comparable opportunities to study evolutionary dynamics of fitness loci in the natural environment.