Meeting Abstract
The Southern Ocean is home to highly endemic benthic fauna. Ophiouroids are a highly abundant and conspicuous member of Antarctica’s benthic assemblages, comprising large percentages of the biomass in many areas. As an important member of the benthic ecosystem, we present data on two supposedly circumpolar ophiuroids (Ophionotus victoriae and Astrotoma agassizii) in an attempt to reveal genetic structure and identify open ocean barriers to dispersal such as depth or geographic distance. O. victoriae has feeding planktotrophic larvae while A. agassizii was thought to brood its young but is now known in its Southern Ocean clade to in part broadcast lecithotrophic larvae. Both of these reproductive strategies could help explain a circumpolar distribution as they provide a means for long dispersal. We utilized two mitochondrial markers, 16S & COI for O. victoriae and 16S & COII for A. agassizii. These genes were amplified for 253 O. victoriae and 188 A. agassizii that ranged from the Ross Sea into the Weddell Sea, a distance of over 5,000 kilometers. Preliminary results have yielded two very different genetic structures. A. agassizii appears to be genetically homogenous within its Southern Ocean clade, while O. victoriae appears to have a more distinct structure through its geographic range. As these initial results depend on just two mitochondrial markers, the use of 2b-RAD genotyping will provide more resolution to the genetic connectivity of both species. This technique has been shown to reveal detailed population structure where traditional markers failed.
