Meeting Abstract

P3.133  Tuesday, Jan. 6  Further studies of predation and aposematism in the dendrobatid frog,Oophaga pumilio, from northeastern Costa Rica KENISON, Erin K.*; SAPORITO, Ralph A.; Skidmore College; Old Dominion University ekenison@skidmore.edu

Organisms use a variety of strategies to defend themselves against predators. Some organisms advertise their defenses to predators with bright colors and/or patterns, a phenomenon known as aposematism. In many cases, predators learn to associate coloration with unprofitability and avoid aposematic organisms, however in some cases avoidance is innate. Brightly colored poison frogs contain an alkaloid-based chemical defense, and it has been recently demonstrated that coloration in the dendrobatid frog, Oophaga pumilio, functions as an aposematic signal to natural predators. Although chemically defended and brightly colored, O. pumilio remains subject to occasional predation. Herein we report the results of two field-based experiments designed to gain a better understanding of aposematism and predation on O. pumilio from Costa Rica. We used plasticine frog models to experimentally evaluate natural predation rates on O. pumilio. In our first experiment, we assessed predation among 4 different habitat types, which differed in forest characteristics and bird abundances. Birds were found to be the most common predator. However, there was no difference in predation among the 4 habitats, suggesting that predation on O. pumilio does not differ with forest structure or predator density. In our second experiment, we examined the importance of color and shape, with regard to the aposematic signal of O. pumilio, by examining predation rates between red and brown-colored, frog and ball-shaped plasticine models. Our results demonstrate that bird predators can distinguish between different colored and shaped models, and suggest that both color and shape are important in the aposematic signal of O. pumilio.