Microgeographic variation of colour morph frequency and biometry of common wall lizards

The throat and belly of both sexes of the common wall lizard Podarcis muralis exhibit a polymorphic coloration with three morphs (white, yellow and red). We documented the occurrence of this polymorphism in 11 populations of northern Italy, and investigated the morphometric features of the three morphs in both sexes. The white morph was more frequent (56.6%), while yellow and red morphs accounted for 28.7 and 14.7% of the lizards, respectively. Moreover, the red morphotype was more frequent among males while the white one was more frequent among females. The occurrence of the three morphs varied microgeographically from populations with a higher proportion of white individuals to those where all morphs were more equally represented. The comparisons of morphometry between morphs did not reveal any significant difference among males, while snout–vent length and head height in females increased from the white-throated to the yellow-throated morph, and from the yellow-throated morph to the red-throated one. Possible functions of this polymorphic coloration are discussed.