Buffering climate driven extinctions in a montane butterfly: are there genetic refuges?

Current genetic diversity in cold-adapted species has been shaped by historical processes over millions of years, including through Pleistocene climatic changes, and anthropogenic climatic change will continue to shape genetic diversity in the future. I used Species Distribution Models to predict past, present and future distributions of the montane butterfly Erebia epiphron and mtDNA sequencing to examine Europe-wide genetic diversity. These analyses revealed that E. epiphron survived in disjunct long-term refugia in continental Europe during previous glacial cycles, resulting in unique genetic diversity which is at risk of being lost in the future. Using mtDNA and ddRAD sequencing, I show that current populations in England and Scotland were colonised separately after the last glacial, experiencing population bottlenecks during colonisation of Britain (Chapter 2 & 3). I also find that the English populations are genetically distinct but have 17% less genetic diversity than Scotland, which is linked to more severe historical bottlenecks in England during post-glacial colonisation (Chapter 3). Morphological studies of body size show that English populations of E. epiphron are ~7-8% smaller than Scottish populations, and smaller individuals occur at warmer locations (Chapter 4). Finally, I used questionnaires to gather opinions on Gene Conservation Units (GCUs) and other genetic conservation measures, and found that UK land managers are supportive of integrating genetic considerations into conservation of wild populations (Chapter 5). Overall, my thesis shows that English populations represent at-risk populations (unique lineage, low genetic diversity, predicted to be lost). In contrast, Scottish populations may have the capacity to act as genetic refuges (higher genetic diversity, predicted to persist). Translocations of at-risk populations could be implemented to ensure species persistence and conserve unique genetic diversity, but further research is required in order to understand more about the types of genetic diversity (uniqueness, diversity) to conserve.