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

Males of a Croatian population of the lacertid lizard Podarcismelisellensis exhibit a striking polymorphism, with colorationof the throat and abdomen ranging from completely white, toyellow or orange. In a first attempt to explore the potentialecological 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 malesare, on average, larger in snout-vent length and have disproportionatelylarger heads than either white or yellow males. This is reflectedin orange males having higher bite force capacity and theoreticallyan increased access to harder prey. Residual limb length, maximalsprint speed and maximal exertion do not differ among colormorphs. Body temperatures in the field are similar in the threemorphs, but yellow males are caught at sites with slightly higherair temperatures than are orange and white males. Behavioralobservations show no differences in time budgets or in the timingof activities among morphs. Microhabitat use is also similarin the three color morphs, but orange males were more ofteninitially seen on rocky substrates. Our findings suggest thatthe observed polymorphism likely does not originate from a divergencein niche or use of resources, but possibly reflects an underlyingpolymorphism in mating tactics.