Morphology, performance, behavior and ecology of three color morphs in males of the lizard Podarcis melisellensis

Abstract

Males of a Croatian population of the lacertid lizard Podarcis melisellensis exhibit a striking polymorphism, with coloration of the throat and abdomen ranging from completely white, to yellow or orange. In a first attempt to explore the potential ecological and evolutionary significance of this polymorphism, we compared the three forms of males in aspects of their morphology, whole-animal performance, behavior, and ecology. Orange males are, on average, larger in snout-vent length and have disproportionately larger heads than either white or yellow males. This is reflected in orange males having higher bite force capacity and theoretically an increased access to harder prey. Residual limb length, maximal sprint speed and maximal exertion do not differ among color morphs. Body temperatures in the field are similar in the three morphs, but yellow males are caught at sites with slightly higher air temperatures than are orange and white males. Behavioral observations show no differences in time budgets or in the timing of activities among morphs. Microhabitat use is also similar in the three color morphs, but orange males were more often initially seen on rocky substrates. Our findings suggest that the observed polymorphism likely does not originate from a divergence in niche or use of resources, but possibly reflects an underlying polymorphism in mating tactics.