Influence of Prey Size on Reproduction among Populations of Diamond-backed Watersnakes (Nerodia rhom

Chamberlain, Jeremy D.

Department of Biology

University of Arkansas at Little Rock

Little Rock, AR USA

Clifton, Ian T.

Department of Environmental Sciences

University of Toledo

Toledo, OH USA

Gifford, Matthew E.

Department of Biology

University of Central Arkansas

Conway, AR USA

Average prey size often varies across landscapes, resulting in predator populations having differing access to energetic resources. Increasing average size of prey provides predators with increased access to energy resources. With additional energy for reproduction, females may maximize fitness by prioritizing allocation towards increasing the size and/or number of offspring. With increased energy resources, individuals may also potentially allocate a higher relative proportion of total energy to reproduction. To test this hypothesis, we evaluated the reproductive allocation patterns of four populations of diamond-backed watersnakes that differ in their average prey size. Snakes at large prey sites produced longer, heavier babies compared to snakes from small prey sites. Statistical interactions among sites confounded our ability to compare differences in litter size, litter mass, and relative clutch mass. Upon removing one small prey population from analyses, reproductive traits became interpretable. Snakes at large prey sites produced similar numbers of offspring as the remaining small prey site. We suggest that increasing energy availability from increased prey size results in additional energy being allocated to offspring size.