62.3 Saturday, Jan. 5 Comparative phylogeography of two ophiuroid species from Antarctica HUNTER, R.L.*; SANTOS, S.R.; HALANYCH, K.M.; Auburn University; Auburn University; Auburn University email@example.com
Isolation of Antarctica has been a driving evolutionary force for Southern Ocean fauna for ~41 million years. Separation of Antarctica from South America and the ensuing onset of the Antarctic Circumpolar Current (ACC) promoted speciation in Southern Ocean marine taxa, many of which presently have circumpolar distributions. This distributional pattern has been attributed to ongoing mechanisms such as dispersal via the ACC and migration along the seafloor, and to historical processes including diachronous deglaciation of the continental shelf. Many Antarctic benthic groups remain unstudied in terms of circumpolar population connectivity. For example, circumpolar distributions are common among Antarctic ophiuroids, however, levels of genetic continuity within ophiuroid species across their range is largely unknown. To begin to assess population connectivity throughout the Antarctic continental shelf, two common ophiuroid species were collected from a portion of their range. Ophiurolepis brevirima was sampled from the northern Antarctic Peninsula and Weddell Sea, and Ophiurolepis gelida was sampled from the Antarctic Peninsula, Ross Sea, and several subantarctic islands. Population structure was evaluated using mitochondrial (16S rDNA) data for O. brevirima and both mtDNA and nuclear (microsatellite loci) markers for O. gelida. Both species are thought to produce lecithotrophic larvae and therefore have potential for larval dispersal. Preliminary mtDNA data are showing evidence of population structure in O. gelida between northern and southern Peninsula populations, whereas northern Peninsula populations are genetically continuous with subantarctic populations, despite being separated by as much as 3500 km. For O. brevirima, a recent population expansion in the northern Peninsula was suggested by parsimony network analyses.