Meeting Abstract

28.3  Monday, Jan. 5  Molecular phylogeography of three Southern Ocean species in the genus, Odontaster (Odontasteridae; Asteroidea) separated by the Drake Passage JANOSIK, A.M*; MAHON, A.R.; HALANYCH, K.M; Auburn University, Auburn, AL; University of Notre Dame, Notre Dame, IN; Auburn University, Auburn, AL janosam@auburn.edu

Many marine invertebrates that possess a life history characterized by a planktonic mode of development often have the potential for vast dispersal. Odontaster validus is one of the most conspicuous seastars in the Antarctic; with a circumpolar distribution extending into the Sub-Antarctic, and has been referred to as a keystone species. By way of a planktotrophic mode of development, O. validus exhibits great potential for dispersal, although the Antarctic Circumpolar Current (ACC) and the Antarctic Polar Front (APF) maybe acting as biogeographical barriers, potentially preventing transport between South American and Antarctic waters. Two other members of this genus in the Southern Ocean, O. penicillatus and O. meridionalis recognized in South America and Antarctica, respectively, exhibit morphological similarity, as well as planktotrophic life history stages. Population structure, genetic connectivity, and distribution of these species have never been rigorously examined using molecular tools. These relationships were examined with a combined mitochondrial 16S ribosomal and cytochrome COI dataset from adult and larval specimens. The results show low genetic differentiation between O. validus populations throughout the Antarctic, but higher differentiation between Odontaster populations across the Drake Passage into South American waters. In addition, conclusions concerning population demographics, species distribution, cryptic speciation, and possible species expansions are discussed.