The genetic structure of founding bumblebee populations in reconstructed prairie habitat 3 years after planting

Abstract

The decline of wild bee pollinators has prompted habitat reconstruction in many regions around the world in order to increase the floral resources available to pollinators. Relatively little research has monitored the genetic differentiation and the relatedness of founding bumblebee populations during the colony recruitment process after vegetation is planted in the landscape. We surveyed nine 3‐year post‐planting reconstructed prairie sites located in the corn belt of the U.S. Midwest, where the landscape is largely dominated by industrialized row crops. Using seven microsatellite loci from 103 Bombus griseocollis, we examined the population genetics of this generalist bee's colonies established on these newly constructed prairie sites. When analyzed, B. griseocollis populations from an older reconstructed site were more genetically distinct from newly established bumblebee populations on reconstructed sites, while the new reconstructed sites exhibited no genetic structure. The floral richness or abundance at the reconstructed sites did not contribute to the allelic richness of the recolonized bumblebee populations. We did, however, find significant negative correlations between the bumblebee populations' allelic richness and the percent coverage of row‐crop farmland in the surrounding landscape and positive correlations between the allelic richness and forest and woody wetland habitat covers. This finding strongly indicates the importance of the composition of the surrounding landscape in the recruitment period of the founding pollinator populations.