The adaptive role of melanin plasticity in thermally variable environments.

This article investigates the adaptive significance of melanin pigmentation plasticity in the white-lined sphinx moth (Hyles lineata) in response to thermally variable environments. The study demonstrates that melanic larvae heat up faster and reach higher body temperatures than non-melanic larvae, conferring a survival and growth advantage in cold conditions, while no clear fitness advantage is observed for either phenotype in warm conditions. These findings support the hypothesis that melanin plasticity is an adaptation to temperature variability, although the costs of melanin production may involve factors unrelated to thermal context. The research highlights the complexity of plastic traits influenced by multiple environmental stimuli and underscores the importance of explicitly testing adaptive roles of plasticity across different environments.