Phylogeography of Eupodes minutus (Acari : Prostigmata) on sub-Antarctic Marion Island reflects the impact of historical events

21 August 2007

Marion Island, situated similar to 2,300 km south-east of Cape Town, South Africa, has experienced multiple volcanic and glaciation events during its history. To better understand the impact of these events on species' genetic structure, we determined the phylogeographic population structure of the mite, Eupodes minutus. We included 57 individuals sampled from 11 localities across the island. Our analyses based on the mitochondrial COI gene suggest a population expansion as would typically be expected when species recover after being confined to refugia. Standard phi (Phi) statistics and a spatial analysis of molecular variance (SAMOVA) identified unique populations on the south-western and south-eastern sides of the island. We argue that multiple volcanic events on the southern side of Marion, in combination with glaciations, effectively isolated these populations from each other.