Contrasting levels of mitochondrial DNA variability between mites (Penthalodidae) and springtails (Hypogastruridae) from the Trans-Antarctic Mountains suggest long-term effects of glaciation and life history on substitution rates, and speciation processes

We carried out a comparative study using mtDNA (COI) for two free-living, endemic, terrestrial invertebrate taxa-the springtail Gomphiocephalus hodgsoni (Hypogastruridae) and the mite Stereotydeus mollis (Penthalodidae) collected from sites throughout Victoria Land and the Queen Maud Mountains, Antarctica. Maximum likelihood (ML) analyses revealed low levels of intraspecific substructuring for G. hodgsoni (⩽2% sequence divergence) with groups mostly corresponding to geographic location. Other well-defined (morphological) species within the Hypogastruridae ranged from 15% to 22% sequence divergence relative to G. hodgsoni. In contrast, ML analyses for S. mollis showed considerably higher levels of intraspecific divergence (up to 18% sequence divergence), suggesting the presence of morphologically cryptic species. Other presently described mite species were also readily discernible (14-18% sequence divergence). Within both G. hodgsoni and S. mollis there were three main groups corresponding to: (1) Taylor Valley; (2) Beaufort Island; and (3) Ross Island together with the adjacent continental sites. We suggest that a common pattern of climatic and geological history over long-term glacial habitat fragmentation have determined the similar geographic and haplotype distributions found for both species. However, a large variation in substitution rate, around eight times slower for G. hodgsoni, compared to S. mollis, may be due to their different life history strategies on the Antarctic continent.