Sexual dimorphism and intra-populational colour pattern variation in the aposematic frog Dendrobates tinctorius
Despite the predicted purifying role of stabilising selection against variation in warning signals, many aposematic species exhibit high variation in their colour patterns. The maintenance of such variation is not well understood, but it has been suggested to be the result of an interaction between sexual and natural selection. This interaction could also facilitate the evolution of sexual dichromatism. Here we analyse in detail the colour patterns of the poison frog Dendrobates tinctorius and evaluate the possible correlates of the variability in aposematic signals in a natural population. Against the theoretical predictions of aposematism, we found that there is enormous intra-populational variation in colour patterns and that these also differ between the sexes: males have a yellower dorsum and bluer limbs than females. We discuss the possible roles of natural and sexual selection in the maintenance of this sexual dimorphism in coloration and argue that parental care could work synergistically with aposematism to select for yellower males.
KeywordsAposematism Polymorphism Sexual dimorphism Parental care Poison frog
This study was funded by two Les Nouragues grants from the CNRS (France), and student research allowances from the School of Psychology at the University of Exeter (UK) and the CIE at Deakin University (Australia), all to BR. P. Gaucher and M. Fernandez provided logistic support. We are thankful to Diana Pizano and J. Devillechabrolle for assistance in the field, and to J. Mappes, J. Valkonen, J. Brown and two anonymous reviewers for thoughtful comments and suggestions that improved the manuscript. This work was done in compliance with the local environmental regulations (research permit issued by CNRS-Guyane) and following ASAB’s guidelines for the treatment of animals in research.
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