Meeting Abstract
Oceanographic processes can affect patterns of genetic variation in marine biota. Large amounts of freshwater coastal outflow can create barriers to gene flow and act as a selective force. Direct developing species may be used to assess environmental influences on local populations because they tend to have lower gene flow and a higher potential for local differentiation. We examined the phylogeography of a direct-developing sea star, Leptasterias, in the San Juan Islands (SJI), WA to assess the potential effects of outflow from the Fraser River, one of the largest sources of coastal freshwater in the Pacific Northwest. Prior phylogenetic analysis of Leptasterias clades around the San Francisco Bay outflow, CA showed a pattern suggestive of selective forces on populations impacted by estuarine outflow, leading to our prediction that freshwater sources may have a strong effect on Leptasterias distribution. In the SJI, preliminary results of mitochondrial cytochrome oxidase 1 (CO1) barcoding (n=97) found three co-occurring clades of Leptasterias: L. aequalis A, L. aequalis B, and L. hexactis. The distribution of these CO1 clade distributions in the SJI suggests that Leptasterias patterns of variation could be related to proximity to plumes from the Fraser River (χ2, p<0.05). Additionally, L. aequalis A and B clades from two Leptasterias complexes dominate populations in WA, while L. aequalis K and clade Y from the same respective complexes dominate populations in CA, indicating a latitudinal difference in clade composition. These results suggest that freshwater sources may influence spatial genetic variation among Leptasterias populations across regions.
