Colour polymorphism in Common wall lizards (Podarcis muralis): causes and consequences

Colour polymorphism is often associated with alternative behavioural strategies (reproductive, territorial, habitat’s use strategies) maintained by different evolutionary mechanisms, such as negative frequency dependent selection. Since 2004 we have been studying the ecological, morpho-physiological, behavioural and genetic causes controlling the evolution and maintenance of the polymorphism in the Common wall lizard (Podarcis muralis), a widespread European lacertid that exhibits a marked colour polymorphism in both sexes. Our researches investigated the patterns of variability in colour morph frequencies, immuno-physiological response of morphs, and morph specific behaviours (such as homing ability). Using ultrasonographic scan of gravid females, we also showed that female morphs adopt different reproductive strategies. The results till now obtained suggests that morphs in Common wall lizards may represent alternative, locally adapted, optima, which may be at the root of sympatric speciation processes through morph loss and phenotype fixation of a single allele.