The distribution and phylogeography of the Alaska marmot (Marmota broweri)

Abstract

The taxonomic and distributional status of the Marmota broweri has been the subject of much debate and confusion since it was first described as a subspecies of the hoary marmot (M caligata). Through a review of all museum specimens, published accounts of this species, field surveys, and the identification of previously unidentified marmot specimens we have determined the current distribution of the Alaska marmot to include the Brooks Range, the Ray Mountains, and the Kokrines Hills of northern Alaska. The Yukon River forms the boundary between the peripatric distributions of M broweri and M caligata in Alaska. Since M broweri was a resident of Beringia during the Pleistocene, I expect the phylogeographic structure of Alaska marmots (M broweri) to exhibit the signature of persistence in Beringia and subsequent expansion into glaciated areas. My objective is to investigate the phylogeographic structure of Alaska marmot populations through phylogenetic tree construction, measures of genetic diversity, a mismatch distribution, and nested clade analysis of DNA sequence data from the mitochondrial cytochrome b gene. I found significant geographic structure across the range of M broweri. The results of my analyses suggest a recent population expansion from central Alaska (Beringia) into the formerly glaciated Brooks Range