Bucking the trend of pollinator decline: the population genetics of a range expanding bumblebee

Recent research has shown drastic reductions in the global diversity and abundance of insects. This is a major concern given expected cascade effects on ecosystem services, such as pollination. Understanding patterns drivers changes distribution species our rapidly changing environment therefore urgent. Cases showing trends that run counter to general population declines, especially when they deliver key are interesting. The tree bumblebee (Bombus hypnorum), which belongs globally important group pollinators, substantially expanded its range recent years direct contrast many other within this group. Here we reconstructed likely pattern colonization UK based RAD-seq genomic data combined with Bayesian modelling. approach also enabled an analysis regions potentially under selection. We report complex dynamic most ongoing. Current evidence suggests either shift migration potential, and/or adaptive have contributed expansion B. hypnorum. Genomic areas potential significance included genes involved regulation transcription gene expression, circadian rhythms innate immunity. Our results framed context understanding factors driving successful expansions.