Phylogeography and population genetics of the Mesoamerican bumble bee species complex, Bombus ephippiatus.

Understanding the historical patterns of biodiversity in complex environments is a principal challenge in evolution. In particular, the geographically complex region of Mesoamerica harbors unusually high levels of biodiversity. Little is known about the genetic diversification of insects in this region, even though they represent a large component of species richness. The bumble bee, Bombus ephippiatus, can serve as a model in which to study insect/pollinator evolution in Mesoamerica. Moreover, bumble bees are important commercial and native pollinators in this region, yet the importation of non-native species for crop pollination has the potential for detrimental ecological consequences throughout the region. Previous phylogenetic research by these authors on Bombus ephippiatus has revealed that this species is a species complex comprising at least four distinct genetic lineages across Mesoamerica, with the Nicaraguan Depression and the Isthmus of Tehuantepec serving as geographic barriers. Using 15 microsatellite loci for over 700 samples from across northern and southern Mexico, Guatemala, and Honduras, we address how the Isthmus of Tehuantepec and various mountain chains in Mexico have shaped the high amount of genetic diversity present within Nuclear Central America.