No evidence for differential survival or predation between sympatric color morphs of an aposematic poison frog
Because variation in warning signals slows down the predator education process, aposematic theory predicts that animal warning signals should be monomorphic. Yet, warning color polytypisms are not uncommon in aposematic species. In cases where warning signal variants are separated geographically, adaptation to local predators could explain this variation. However, this cannot explain the persistence of sympatric polymorphisms in aposematic taxa. The strawberry poison frog (Oophaga pumilio) exhibits both allopatric and sympatric warning color variation in and around the Bocas del Toro archipelago of Panama. One explanation that has been proposed for the rapid diversification of O. pumilio coloration in this archipelago is low predation; if island populations have few predators, stabilizing selection would be relaxed opening the door for diversification via selection or genetic drift. Using a combination of mark-recapture and clay model studies, we tested for differences in survival and predation among sympatric red and yellow color morphs of O. pumilio from Bastimentos Island. We found no evidence for differential survival or predation in this population, despite the fact that one morph (red) is more common and widely distributed than the other (yellow). Even in an area of the island where the yellow morph is not found, predator attack rates were similar among morphs. Visual modeling suggests that yellow and red morphs are distinguishable and conspicuous against a variety of backgrounds and by viewers with different visual systems. Our results suggest that general avoidance by predators of red and yellow, both of which are typical warning colors used throughout the animal kingdom, may be contributing to the apparent stability of this polymorphism.
KeywordsColor polymorphism Polytypism Aposematism Bocas del Toro Dendrobates pumilio Predation Survival
We thank Narissa Bax, Sebastian Castillo, Ricardo Cossio, Anisha Devar, Deyvis Gonzalez, Eli Hornstein, Danny Lenger, Tom Richards, Becky Richards, Eric Rightley, Tracy Stetzinger, Geoff Zawacki and Amanda Zellmer for help with the mark-recapture study and to Anisha Devar for help with the predation experiment. The STRI provided logistical support for this project and we are particularly grateful to Gabriel Jacome and Plinio Gondola of the Bocas del Toro Field Station. This study was financially supported by short-term fellowships from STRI to CLRZ and JY, postdoctoral fellowships from the National Science Foundation (Award No. 0801165) and the University of California President’s office to CLRZ, and a Tulane Dean’s grant to HPSB. The Panamanian National Authority for the Environment (ANAM) provided research permission for this study. This work complied with IACUC protocols (University of Michigan No. 09765, Tulane University No. 0832 and STRI No. 2007-17-12-15-07).
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