Where and when local adaptation happens: lessons from the European barn owl (Tyto alba)

Abstract

AbstractClimatic variations subject living species to evolutionary stresses and shape their distributions. Since the Last Glacial Maximum (LGM) and the subsequent temperature rise, species (re-) colonised higher latitudes. Among the evolutionary mechanisms involved during this process, local adaptation is thought to be one of the keystones of species persistence. However, its relative role and location in space remain elusive. The Western Palearctic barn owl (Tyto alba) recolonised Europe after the LGM (from the Italian and Iberic peninsulas) and offers an excellent opportunity to study local adaptation at the continental scale. Here, we modelled the evolution of the barn owl’s ecological niche since LGM and showed that the birds probably followed its shift towards the North during the recolonisation. To identify traces of local adaptation, we scanned the entire genomes of 74 owls from 9 European populations using both Tajima’s D and population-specific FST and associated genomic variants to temperature and precipitation through a Redundancy analysis. The combination of these methods yielded a total of 394 genomic windows putatively involved in the local adaptation distributed over all populations. Interestingly, our results identified a large region under selection in both refugial populations, consistent with climate change and ecological convergence in the two peninsulas. This study shed light on the genomic basis of local adaptation of the European barn owl, emphasised the importance of considering the ecological niche as a dynamic entity and paved the way to a better understanding of where and how local adaptation happens in a context of postglacial recolonisation.