Data from: Geography, genetic structure, and consequences of Pleistocene climate in a Holarctic defoliator, the gypsy moth (Lymantria dispar, Lepidoptera: Erebidae)

The gypsy moth (Lymantria dispar Linnaeus) is among the most destructive pest insects in the world. Native to Europe and Asia and introduced to North America 145 years ago, the current distribution of gypsy moth includes forests throughout the entire temperate region of the northern hemisphere. Given its Holarctic distribution and economic importance, we have used molecular markers to define current population structure and evolutionary history of L. dispar and to evaluate how both geographic and environmental factors have shaped patterns of genetic variation in this species. Sampling a large number of moths from across the current distribution, we identified four genetic clusters representing four distinct geographic areas. These clusters correspond to three named subspecies that occupy geographically distinct regions. Introduced North American populations represent a unique cluster, presumably a consequence of an initial population bottleneck and subsequent allele frequency change. MtDNA dating suggests that initial diversification in L. dispar was driven by a significant increase in the amplitude of glacial/interglacial variability since the Middle Pleistocene, a time when temperate forests expanded and contracted on the Eurasian continent. Deeply diverged matrilines in the European L. d. dispar imply that Europe has long been occupied by L. dispar, where it was at times restricted to multiple glacial refugia. Although changes in climate have driven diversification within L. dispar, they have also led to secondary contact and extensive hybridization.