Fine scale distribution of mtDNA haplotypes for the springtail Gomphiocephalus hodgsoni (Collembola) corresponds to an ancient shoreline in Taylor Valley, continental Antarctica

We examined the fine scale distribution of the endemic Antarctic collembolan Gomphiocephalus hodgsoni in Taylor Valley, southern Victoria Land using the mitochondrial DNA cytochrome c oxidase I gene. We found an area of sympatry in the mid-region of the valley between two common haplotype groups (2.4% sequence divergence). The area of sympatry coincided with the extent of proglacial Lake Washburn (approx. 8,000 ya). This lake existed as a result of the damming of lower Taylor Valley by the grounding of the Ross Ice Sheet and may have acted as an isolating barrier to dispersal/gene flow. We suggest that the phylogenetic break occurring in the vicinity of the ancient shoreline may be the result of previous isolation of refugial allopatric populations, followed by recolonisation into a secondary contact zone during the Holocene.