Anatomy of a cline: dissecting anti-predatory adaptations in a marine gastropod along the U.S. Atlantic coast

The scope of anti-predatory adaptation is expected to be greater in warm than in cold environments. High temperatures lower the costs associated with the production and maintenance of energetically expensive traits and enable ecological interactions to intensify. We tested this hypothesis by characterizing the expression of anti-predatory morphology within a marine gastropod species (the knobbed whelk, Busycon carica) over a large (>1,400 km) geographic area that spans more than 10°C annual temperature variation. We also conducted experimental predation studies with a powerful durophagous predator, the stone crab (Menippe), to verify the anti-predatory advantages of a heavily ornamented shell morphology (e.g., increased thickness, pronounced spines), and we used repair scar data to assess clinal variation in selective pressure from predators. We predicted that repair scar rates would be greatest in warm southernmost latitudes, and that expression of energetically costly anti-predator...