Genetic diversity and differentiation of honey bees in the United States

In their native range, honey bees are divided into about twenty-eight morphologically, genetically, and behaviorally distinct subspecies. Historical evidence shows nine of these subspecies have been imported to the United States over the past four hundred years. After arriving in the US, honey bee populations experienced disease-driven bottlenecks, and natural and artificial selection. Furthermore, they interbred with other introduced subspecies to produce admixed stocks. At present, there are two major honey bee populations: managed and feral. Managed honey bees are under human control and therefore receive regular colony manipulation to control disease, suppress swarming, and increase reproductive output. Feral honey bees are loosely defined as any colony occupying an unmanaged home site. The distinction between the two has been debated; feral colonies have been proposed as genetically discrete populations or, alternately, recent escapees from nearby managed colonies. We have sequenced the mitochondrial and whole genomes of three feral honey bee populations (Pennsylvania, Kentucky, and North Carolina) as well as stocks of managed honey bees. Ancestry, mitotype distribution, genetic diversity, and genetic differentiation suggest feral honey bees are closely related to managed colonies, but nonetheless exhibit population-level differences on certain loci.