Trait differences among discrete morphs of a color polymorphic lizard, Podarcis erhardii

Color polymorphism defies evolutionary expectations as striking phenotypic variation is maintained within a single species. Color and other traits mediate social interactions, and stable polymorphism within a population is hypothesized to be related to correlational selection of other phenotypic traits among color morphs. Here, we report on a previously unknown throat color polymorphism in the Aegean Wall Lizard (Podarcis erhardii) and examine morph-correlated differences in traits important to social behavior and communication: maximum bite force capacity and chemical signal profile. We find that both sexes of P. erhardii have three color morphs: orange, yellow, and white. Moreover, orange males are significantly larger and tend to bite harder than yellow and white males. Although the established color polymorphism only partially matches the observed intraspecific variation in chemical signal signatures, the chemical profile of the secretions of orange males is significantly divergent from that of white males. Our findings suggest that morph colors are related to differences in traits that are crucial for social interactions and competitive ability, illustrating the need to look beyond color when studying polymorphism evolution.
This work received funding from the National Geographic Society (Waitt Grant W470-16), the Society for the Study of Evolution (Rosemary Grant Award), the American Philosophical Society (Lewis and Clark Fund for Exploration and Field Research), and the University of California, Merced Graduate Division (Faculty Mentor Fellowship, California Edison Fellowship, William Shadish Fellowship, and Fred & Mitzie Ruiz Fellowship) with fundsawarded to Kinsey M. Brock. Simon Baeckens is a postdoctoral fellow supported by the FWO-Flanders (12I8819N).