Dorsal pattern polymorphism in female Iberian wall lizards: differences in morphology, dorsal coloration, immune response, and reproductive investment

Abstract

Sex-specific colour polymorphisms have been extensively documented in many different taxa. When polymorphism in colour pattern is restricted to females, the condition is known as female-limited pattern polymorphism (FPP), which has been less commonly addressed in vertebrates. FPP is present in several lizard species, although most research on lizards has focused on carotenoid- and pteridine-based coloration and not on melanin-based polymorphisms. In the present study, we focus on Iberian wall lizards, Podarcis hispanicus, where two female melanin-based dorsal patterns can be clearly distinguished: striped and reticulated-blotched. We indirectly tested the hypothesis that selection acts differentially among P. hispanicus female morphs to create alternative morph-specific phenotypic optima at different levels by investigating whether morphs differ in fitness proxies. We specifically examined whether the two female dorsal pattern morphs differed in adult morphology, dorsal coloration, immune response, reproductive investment, and growth. We did not find a relationship between melanin-based coloration and hatchling growth and immune response, despite a correlation between these traits possibly being expected as a result of pleiotropy in the melanocortin system. However, our results show that female dorsal morphs in P. hispanicus differ in terms of adult morphology, dorsal coloration, and reproductive investment. Reticulated-blotched P. hispanicus females had deeper heads and longer femora, less melanin, and more brownish coloration, and also had larger and heavier hatchlings than striped females.