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Local adaptation in marine speciesMarine species are often distributed over thousands of kilometers of coastline and thus separate populations can experience strikingly different environments. However, we know surprisingly little about the extent to which persistent oceanographic variation might shape evolutionary differences among populations of marine species. We have been addressing this question using the channeled dogwhelk (Nucella canaliculata), a predatory snail that inhabits rocky intertidal mussel beds. Initial observations suggested that snails from California readily drilled the thick-shelled mussel Mytilus californianus, whereas snails from Oregon populations seldom drilled this prey. Our recent results from laboratory breeding studies indicate that this variation in drilling capacity has a genetic basis. In addition, results from field experiments suggest that these regional differences in the drilling ability of snails reflect local adaption to variation in prey recruitment in California versus Oregon. More broadly, our results suggest that geographic mosaics of selection imposed by persistent oceanographic variation can shape adaptive differentiation among populations of marine species in adjacent coastal regions. We are continuing to combine field studies, laboratory experiments, and analyses of molecular markers (microsatellites) to investigate (1) the scale at which adaptive differentiation occurs in marine species, and (2) the ecological consequences of these patterns.
Dogwhelk, mussels, and egg capsules (left), and dogwhelks feeding on prey (right). Selected publications: Sanford, E. and D.J. Worth. Local adaptation along a continuous coastline: prey recruitment drives differentiation in a predatory snail. Ecology, in press. Sanford, E. and D.J. Worth. 2009. Genetic differences among populations of a marine snail drive geographic variation in predation. Ecology, in press. Sanford, E., M.S. Roth, G.C. Johns, J.P. Wares, and G.N. Somero. 2003. Local selection and latitudinal variation in a marine predator-prey interaction. Science 300: 1135–1137.
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Funding for this work is provided by the