Paleoenvironmentally correlated differences in a classic predatory-prey system: the bivalve Chione elevata and it gastropod predators

The importance of understanding ecophenotypy in studies of morphological evolution is widely appreciated. Behavioral traits can be environmentally plastic, yet studies of behavioral evolution often proceed without careful consideration of the environmental context. The interaction of Chione elevata with its epibionts and gastropod predators in two shallow marine facies from the Pleistocene of Florida, corresponding to the Bermont and the overlying Fort Thompson Formations, were examined.

Fort Thompson samples exhibit roughly an order of magnitude more abundant C. elevata and significantly lower predation intensities than those of the Bermont Formation. Predator size, as measured by the outer borehole diameter, does not differ between facies, but selectivity for larger-sized prey is significant only in the Fort Thompson Formation. These differences in predator behavior may have resulted from ecological differences between facies. Evolutionary studies of behavior that fail to consider the ecological context of each sample will be flawed.