Geographically separated populations of Bombus terrestris audax exhibit genomic distinctions and differential signatures of selection

Understanding intraspecific variation is crucial for effective conservation of biodiversity. Pollinator species, many of which are flying insects, can have wide distributions that span many kinds of environments. Variation within a species can then be caused by factors such as geographical barriers to gene flow and local selection pressures. Therefore, islands are hubs for distinctive biodiversity. As essential pollinator populations have reported declines, understanding intraspecific variation of vulnerable populations, as well as their capacity to respond to ongoing environmental challenges, is essential. In this study, we focus on a subspecies of bumblebee, Bombus terrestris audax, native to the islands of Ireland and Britain. A comparative whole-genomics analysis on B. t. audax from each island, in addition to commercial and mainland European B. terrestris samples, was conducted to evaluate B. t. audax population structure. We also investigated differential signatures of selection acting on the two island populations by assessing variant frequencies and extended haplotype homozygosity.