Genetic Differences in Purple Finch (Haemorhous purpureus) Are Linked With Subspecies and Migratory Behaviour...

Seasonal migration patterns and geological barriers can impact population structure. In particular, migratory behaviour (resident vs. migratory) differences are thought to promote genetic structure within species. Using a ddRADseq approach, we genotyped 43 purple finches (Haemorhous purpureus) from eight populations across their range comprising both subspecies and examined the effect of migratory behaviour on population structure in this species. We also used genome scans to identify loci under selection and tested whether these differences are associated with migratory behaviour differences. The two subspecies were genetically distinct and within H. p. californicus, we found that populations formed three genetic clusters. Population structure was not strongly associated with resident or migratory behaviour, although we did identify five regions under selection that were distinct between migratory and resident populations. Two of the genes identified in these scans were related to ghrelin hormone and liver fat deposit; Ghrelin is a key component of migratory restlessness, while liver fat deposits are used to fuel migration in birds. Combined our results suggest that population genetic differences between subspecies reflect historical isolation during the Last Glacial Maximum, and indicate that some genetic differences occur between resident and migratory populations. These genetic differences appear to be associated essential for pre-migratory and migratory behaviour in birds.