Ghosts of glaciers and the disjunct distribution of a threatened California moth (Euproserpinus euterpe)

Abstract

The Kern Primrose Sphinx moth (Euproserpinus euterpe) is a threatened moth twice thought to have gone extinct. It was historically known only from a small basin in the southern Sierra Nevada of California, but a new putative population was recently discovered 115km to the west. Analysis of both nuclear and mitochondrial DNA suggest discontinuous genetic breaks between the Kern Primrose Sphinx, its closest relative the Phaeton Sphinx (Euproserpinus phaeton), and at least one additional species discovered during the course of this study. Geographic distance is well correlated with genetic distance within species, but not between species. Genetic discontinuities show the influence of past glacial events and suggest recent range expansions, though not always congruent with other phylogeographic studies from the region. Our phylogeographic results demonstrate that past glacial events, the altitudinal suppression of suitable habitat, and isolation may have been more important than population-level ecological factors such as differences in habitat (e.g. sand dunes, oak forest, montane grasslands) in promoting speciation. Effective conservation of the genetic diversity of the widespread Phaeton Sphinx and its two geographically restricted relatives requires genetic data at the population level because relatively few localized populations harbor most of the genetic variation.