COX, N.L.*; HALANYCH, K.M.; Auburn University, Alabama: Phylogeography of Sterechinus neumayeri from South American and Antarctic waters using the 16S mtDNA marker

Separation of South America and Antarctica, approximately 30 million years ago, led to the creation of the Drake Passage and the Antarctic Circumpolar Current, subjecting Antarctic benthic fauna to isolation for nearly 25 million years. Despite this isolation, some invertebrate taxa include more than 40% non-endemic species, suggesting present day gene flow across the Drake Passage maintains genetic continuity. Molecular phylogenetic work is currently being done using the 16S mitochondrial gene from Sterechinus neumayeri, the most abundant echinoid genus in Antarctica, and morphologically similar populations from South America. S. neumayeri is a model candidate for this study because it has a circumpolar distribution and planktotrophic larvae, which are abundant in the plankton during the short summer. Samples have been collected from South America, the Drake Passage, and Antarctica on a cruise during November-December 2004. With the mitochondrial data, we are assessing the level of genetic differentiation between the populations to identify genetic breaks, historical gene flow, and endemicity.