Camouflage, conspicuousness, and inducible color change in a polymorphic, sexually dichromatic frog.

Sexual dichromatism is prevalent throughout the animal tree of life and can play an important role in visual signaling and mate choice in many species. Some instances of sexual dichromatism, however, result from a combination of mechanisms including sexual niche partitioning and intrasexual signaling to identify competitors. Sexual dichromatism is relatively rare in anuran amphibians (frogs and toads) but is striking and prevalent in the African reed frogs (Hyperoliidae). In sexually dichromatic hyperoliids, males and females exhibit shared coloration post-metamorphosis, but at the onset of maturity, females undergo a change in color and/or color pattern whereas males typically retain the juvenile coloration. Hypothesized functions of dichromatism in reed frogs include sexual niche partitioning such that males and females use different habitats and their different colorations provide more effective camouflage in their respective habitats or alternatively, that color patterns play a role in sex and/or mate recognition in dense breeding choruses. To test these hypotheses, we characterized several aspects of natural history, ecology, and physiology in a population of the sexually dichromatic forest reed frog (