Behavioural elements reflect phenotypic colour divergence in a poison frog
The coexistence of both aposematic and cryptic morphs as different anti-predator strategies within a species seems to be an unusual phenomenon in nature. The strawberry poison frog, Oophaga pumilio, shows an astonishing colour diversity among populations in western Panama. In this study we selected a red and a green colour morph from two Panamanian islands (Isla Solarte and Isla Colón) for behavioural observations and measurements of conspicuousness. We found that red frogs were more visible to both conspecific frogs and potential predators than green frogs. Interestingly the difference in conspicuousness was most pronounced at the substrate that males used as principal calling places. Red males were more active and spent more time foraging than green males, which spent more time hidden. The association between conspicuousness of colouration and behaviour results in a more aposematic and a more cryptic anti-predator strategy. This is the first study which links differences in conspicuousness between animals on their natural backgrounds to differences in foraging as well as anti-predator behaviour and discusses the results in light of previous findings of toxicity analyses and potential costs and benefits of aposematism. To this end, our study adds a novel perspective for explaining extreme colour diversity between populations within an initially aposematic species.
KeywordsAposematism Crypsis Colour diversity Anti-predator strategy Oophaga pumilio Poison frog
We thank Martine Maan, Adolfo Amezquita, Corinna Dreher and two anonymous referees who provided helpful insights on the manuscript. Rüdiger Brüning and Sönke von den Berg helped with figure preparation. We are especially grateful to Thomas Cronin from the University of Maryland who provided the sensitivity spectra for the photoreceptors of strawberry poison frogs and Nathan Hart from the University of Queensland who provided sensitivity spectra for the photoreceptors of blue tits.
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