The common wall lizard (Podarcis muralis) is a species of lizard with a large distribution in Europe and well-established introduced populations in North America, where it is also called the European wall lizard. It can grow to about 20 cm (7.9 in) in total length. The animal has shown variation in the places it has been introduced to. Fossils have been found in a cave in Greece dating to the early part of the Holocene.
Description The common wall lizard is a small, thin lizard whose small scales are highly variable in colour and pattern. Its coloration is generally brownish or greyish, and may occasionally be tinged with green. In some individuals, the row of spots along their backs may form a line, while others may have a reticulated pattern with dark spots on the side and scattered white spots that can be blue in the shoulder region. The tail is brown, grey or rust in colour, and may also have light bars on the sides. The belly region has six rows of larger rectangular scales that are generally reddish, pink, or orangish. Common wall lizards may also have dark markings on the throat. This lizard has six distinct morphological forms which are identified by the colouration of its throat and underbelly. Three of these are pure morphs consisting only of solid colours on their scales: white, red (orange) or yellow, and three other morphs are distinguished by a combination of colours: white-yellow, white-red and yellow-red. On average, eggs are about 11 x 7 mm and weight 0,29 g at deposition, and absorb water up to 16 x 10 mm and 1 g.
Ecology The common wall lizard prefers rocky environments, including urban settings, where it can scurry between rock, rubble, debris and buildings. In the southern part of its range it tends to occur in humid or semi-humid habitats, compared to drier habitats in the north.
Chemical communication Common wall lizards rely both on visual and chemical signals to communicate with conspecifics. Male wall lizards are equipped with femoral glands, which produce a waxy secretion used for chemical signalling. Both the proteinic and lipophilic compounds in the secretions are known to carry socially relevant information.
Polymorphism The six morphs of this lizard are primarily identifiable by colour and can be distinguished with the naked eye. However, they are commonly confirmed by digital photo and colour analysis. Source of colouration comes from different pigments within the lizard, with yellow colouration originating from carotenoids, and the expression of red/orange colour from pteridines. This is indicative that a phenomenon such as multiple alleles or epistasis may have a role in determining morphology. Morphs also differ in aspects other than colouration: differences between morphs are seen with femoral gland secretion, immune competence and body size. For males, colouration is visible on the underbelly, but in females of all the morphs there is less colouration seen in this region, indicating that sexual dimorphism occurs within this species. A study found sexual dimorphism in the digit ratios. Namely, they found a significant difference (after Bonferroni correction) of the 2D:4D ratio on both forepaws and the 2D:3D ratio on the left forepaw, with all ratios being larger in male animals. This study was conducted on a sample set of 18 male and 18 female museum specimens.
Variations between morphs
Aside from differences in colour, the morphs vary by length, survival rate, and immune resistance/response to infection.
… excerpt ends here. Continue reading the full article.
