Influence of Feeding Regime on Growth and Body Size in the Boa (Boa Imperator)

Kryzsko Commons Ballroom, Winona, Minnesota

Because snakes are gape-limited predators, much emphasis has been placed on the role of prey size in inducing plastic changes to trophic morphology. In contrast, few studies have researched the effect of feeding frequency on growth and body size, even though many snakes experience long fasting periods between meals. We conducted an experimental, multiple year study of growth in Boas, (Boa imperator) that experienced different feeding regimes. Three liters of full siblings were randomly assigned into two groups. One group received a meal equal to 5% of their body mass every 7 days and the other group received a meal equal to 25% body mass in food every 35 days. Using x-ray radiographs, we measured body size and a several skeletal morphological variables before the feeding regimes began and annually thereafter. We observed that those boas fed frequently grew larger in body mass and exhibited greater robustness, whereas boas feed infrequently had lower body mass and were laterally compressed. Our results suggest that phenotypic plasticity resulting from feeding frequency may play a role in morphological diversity. Further, the changes we observed mirrored the evolutionary changes of mainland and island populations boas from Central America.