A Study On The Variations In Timing, Physiology And Function Of Colour Change In Amphibians

Abstract

Amphibians have the incredible ability to change colour, yet the hormonal drivers and evolutionary functions are poorly known in most species. Herein we review the variations in timing, physiology and function of colour change in amphibians. Additionally, we investigate how sexual selection may drive colour change in anuran amphibians by examining breeding pattern and reproductive behaviour of sexually dichromatic species and relating these to function.

We identify three patterns of colour change based on speed, hormonal mechanisms and ecological function. 1. Ontogenetic colour change is a unidirectional, permanent change from a juvenile to an adult colour phase. The function of this change is mostly unknown but is driven by natural and sexual selection processes. 2. Seasonal colour change is a temporary colour change that occurs over weeks or months. It commonly occurs in sexually dichromatic, explosive breeding species, where it functions as an intrasexual signal for sex recognition. 3. Rapid colour change occurs in just minutes or hours and is also reversible. It is commonly used as for camouflage or thermoregulation (78%). In some species (22%) only males change colour and this predominantly occurs in prolonged breeders where it functions as an intrasexual signal.