Conserved, yet disruption-prone, gut microbiomes in neotropical bumblebees.

Social bees are an important model for the ecology and evolution of gut microbiomes. These bees harbor ancient, specific, and beneficial gut microbiomes and are crucial pollinators. However, most of the research has concentrated on managed honeybees and bumblebees in the temperate zone. Here we used 16S rRNA gene sequencing to characterize gut microbiomes in wild neotropical bumblebee communities from Colombia. We also analyzed drivers of microbiome structure across our data and previously published data from temperate bumblebees. Our results show that lineages of neotropical bumblebees not only retained their ancient gut bacterial symbionts during dispersal from North America but also are prone to major disruption, a shift that is strongly associated with parasite infection. Finally, we also found that microbiomes are much more strongly structured by host phylogeny than by geography, despite the very different environmental conditions and plant communities in the two regions.