Seasonal Phenotypic Variation in the Aeolian Wall Lizard, Podarcis raffonei, of the Capo Grosso (Vulcano) Population

Abstract

In recent decades, studies on animal coloration have expanded significantly, from understanding color production and perception mechanisms to exploring the selective pressures driving these patterns. Conservation biology has begun leveraging these studies to develop effective strategies, gauge public support for conservation projects, select flagship species, and determine reproductive pairs and optimal rearing and release conditions for captive breeding. Critically endangered Aeolian wall lizards (Podarcis raffonei) were housed at the Fondazione Bioparco di Roma for a pilot captive breeding project following alarming hypotheses of rising numbers of “green” hybrids (P. raffonei × P. siculus) in one of the four surviving populations. Through a quantitative analysis of visible dorsal color in captive and natural populations, we aim to determine whether P. raffonei is characterized by seasonal variation in its dorsal coloration and if color is influenced by sex and ontogenesis. Our findings show that P. raffonei’s dorsal pigmentation varies between seasons. In spring, the size and age of the animals does not seem to affect any color component, while the sexes always differ in their hue, with males having consistently more yellow-green dorsa. Between-year analyses, including measurements from the wild population, indicate that yearly variation is not limited to the captive population but also occurs in nature. We caution against identifying potential hybrids based solely on phenotypic traits.