The phenotypic variability in Rana temporaria decreases in response to drying habitats

•Drought is hypothesized to impact the phenotypic variability of Rana temporaria.•A new non-invasive method was implemented to test such effect.•Phenotypic variability decline was found in frogs developing in drying habitats.

In this study, we evaluated the diversity of skin coloration as a proxy for phenotypic diversity. The European common frog (Rana temporaria) populations from the Southern slope of central Pyrenees lie at the limit of the species distribution in latitude and altitude. We analysed the relationship of skin color typology with different environmental variables and found a large decrease in skin type variety in frogs developing in temporary water bodies when compared to those developing in permanent water bodies. Our results show that our method can be used as a non-invasive way to study phenotypic diversity and suggest that adaptation to an early metamorphosis in a rapidly-drying habitat can have negative effects on adult phenotypic diversity. In light of these results, we argue that access to permanent water bodies is important to prevent loss of diversity in anuran populations and reduce their vulnerability to environmental impacts as well as pathogens.

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