A population genetics study of the wood-boring bivalve, Xylophaga washingtona, from wood-fall experiments along OR and WA, USA

A widely distributed species of wood-boring bivalve, Xylophaga washingtona, was collected from three sites along the Washington-Oregon margin and assessed with molecular techniques. 16S gene sequences revealed low differentiation between individuals from the two sites on the outer continental slope suggesting that these sites harbor a single population. However, greater genetic distance was observed between the slope individuals and those collected from a shallow-water site in the San Juan Islands, Washington. These results suggest the presence of at least two distinct populations of Xylophaga washingtona along the Washington-Oregon margin and the potential for species-level differences. The juxtaposition of the two hydrographic settings supports the hypothesis that isolation of the shallow-water population has resulted in sufficient genetic differentiation over fairly short geographic distances. Further research is needed to verify these observed patterns and to explore whether morphological differences support the proposed population and species structure