Population genetic structure of the New Zealand estuarine clam Austrovenus stutchburyi (Bivalvia: Veneridae) reveals population subdivision and partial congruence with biogeographic boundaries

Abstract

We examined the population genetic structure of the New Zealand endemic clam, Austrovenus stutchburyi, to determine (1) whether populations of this estuarine taxon are genetically subdivided and (2) if the locations of genetic boundaries were congruent with known biogeographic break points. We obtained sequences of the mitochondrial gene cytochrome c oxidase I for 372 A. stutchburyi from 29 New Zealand estuaries and conducted analyses to identify population genetic structure. We detected a pattern of genetic isolation by distance and identified six A. stutchburyi subpopulations, a greater number of subpopulations than reported for much of New Zealand’s open coast benthos. Although these data indicate that long distance dispersal may be less frequent in estuarine than in open coast taxa, partial congruence between genetic and biogeographic boundaries suggests that historical events and natural selection may also contribute to the observed population genetic structure.