This week the department is pleased to welcome Debbie Leigh from Queen’s University.

Bottlenecks, evolution and the behavior of selected variation

Can recent adaptive responses be identified after a population crash? Moreover, can signals of selection be distinguished from allele frequency change due to drift? Our understanding of the on-going evolutionary processes through a population bottleneck is limited. Adaptation experiments and population genetic theory suggest that a bottleneck will have far reaching consequences on the potential for, rate, and direction of adaptation.  However our ability to characterise and explore these effects within naturally bottlenecked systems is often limited by the confounding effects of drift-driven false positive signals of selection.

Within this study we explored if signals selection could be accurately distinguished from drift across 23 bottlenecked and reintroduced populations of Swiss Alpine ibex (Capra ibex). To this end, a set of simulated neutral markers and adaptive markers contributing to a polygenic trait with a shifting local optimum, were generated under the reintroduction history. Through this approach we quantified the false and true positive rates of three different selection-detection softwares and found high detection-accuracy is achievable through overlapping outlier lists and incorporating environmental data in outlier detection. By employing this approach within the Alpine ibex RADseq SNP data, we identified a candidate adaptive response with moderate confidence in relation to the depth of winter snow, an environmental variable known to drive mortality events in the species. 

The EEB Seminars run weekly, on Thursdays, in the EEB Lounge of the BioSciences Complex, Room 4338, from 12:30-1:30pm.