Climate shapes population variation in dogwhelk predation on foundational mussels.

Trait variation among populations is important for shaping ecological dynamics. In marine intertidal systems, seawater temperature, low tide emersion temperature, and pH can drive variation in traits and affect species interactions. In western North America, Nucella dogwhelks are intertidal drilling predators of the habitat-forming mussel Mytilus californianus. Nucella exhibit local adaptation, but it is not known to what extent environmental factors and genetic structure contribute to variation in prey selectivity among populations. We surveyed drilled mussels at sites across Oregon and California, USA, and used multiple regression and Mantel tests to test the effects of abiotic factors and Nucella neutral genetic relatedness on the size of mussels drilled across sites. Our results show that Nucella at sites characterized by higher and less variable temperature and pH drilled larger mussels. Warmer temperatures appear to induce faster handling time, and more stable pH conditions may prolong opportunities for active foraging by reducing exposure to repeated stressful conditions. In contrast, there was no significant effect of genetic relatedness on prey size selectivity. Our results emphasize the role of climate in shaping marine predator selectivity on a foundation species. As coastal climates change, predator traits will respond to localized environmental conditions, changing ecological interactions.