BLUE LIZARD

Podarcis siculus is a lacertid lizard characterised by considerable variability in coloration pattern. In this species underside is usually whitish or greyish, always without dark spots. However, in some small island populations from Italy individuals can be allochromatic, i.e. completely black (melanic), bluish, or with a blue belly (e.g. the famous “blue lizard” – P. siculus coerulea - from Faraglione di Fuori and Faraglione di Mezzo islets, near Capri Island, Campania, southern Italy).
It must be noted that, in some cases at least, melanic individuals can be observed also in continental areas (e.g. Roscigno, Campania, southern Italy).
The evolutionary significance of the allochromatic patterns is still unclear, and some hypotheses were done to explain their origin.
(...) In Campania individuals with bluish or dark underside were observed both on small islands and on some continental areas. However, in continental areas the frequency of allochromatic individuals seems to be lower than on islands.
It is noteworthy that the P. siculus populations from Campania, which are characterized by a high degree of phenotypic plasticity also in the pattern of the upper parts, have levels of genetic variability higher than those found in the morphologically low variable populations from central and northern Italy.