Meeting Abstract
When a species colonizes a new environment there are likely to be phenotypic changes associated with the colonization. These phenotypic changes are driven by novel environmental pressures unique to the newly inhabited areas. We studied the response of diamond-backed watersnake (Nerodia rhombifer) to colonization of novel environments with different prey regimes than the “ancestral” environments. Feeding morphology is likely to be influenced by prey size, especially in gape-limited predators. While N. rhombifer typically occupy natural areas such as rivers, sloughs, and oxbows, they have also colonized man-made fish farms. These farms tend to specialize in the types of fish they produce with some farms raising large-bodied fish and others raising small-bodied fish. Our study suggests that snakes that colonized large-prey sites have evolved relatively larger heads than those snakes that colonized small-prey sites. To explore whether the cranial variation observed among populations could be a consequence of a genetic response to selection, we provide evidence of significant heritability for all cranial traits.
