Its natural habitats are Mediterranean-type shrubby vegetation, rocky areas, rocky shores, sandy shores, rural gardens, pastureland, plantations and urban areas.
Subspecies
P. siculus contains dozens of subspecies. The current distribution patterns of the subspecies have been interpreted as the consequence of natural events, including regional glacial refuges and postglacial area expansions, and multiple introductions by man. The island endemic Santo Stefano lizard became extinct in 1965 after introduction of predators, interbreeding with introduced wall lizards, and a disease epidemic which wiped out the last remnants. List of subspecies: Podarcis siculus adriaticus, Podarcis siculus aemiliani, Podarcis siculus amparoae, Podarcis siculus astorgae, Podarcis siculus bagnolensis, Podarcis siculus bolei, Podarcis siculus calabresiae, Podarcis siculus campestris, Podarcis siculus caporiaccoi, Podarcis siculcus attaroi, Podarcis siculus cettii, Podarcis siculus ciclopica, Podarcis siculus coeruleus, Podarcis siculus cucchiarai, Podarcis siculus dupinici, Podarcis siculus fiumanoideus, Podarcis siculus flavigulus, Podarcis siculus gallensis, Podarcis siculus hadzii, Podarcis siculus hieroglyphicus, Podarcis siculus insularus, Podarcis siculus klemmeri, Podarcis siculus kolombatovici, Podarcis siculus laganjensis, Podarcis siculus lanzai, Podarcis siculus latastei, Podarcis siculus massinei, Podarcis siculus monaconensis, Podarcis siculus nikolici, Podarcis siculus palmarolae, Podarcis siculus pasquinii, Podarcis siculus paulae, Podarcis siculus pelagosae, Podarcis siculus pirosoensis, Podarcis siculus pohlibensis, Podarcis siculus premudanus, Podarcis siculus premudensis, Podarcis siculus pretneri, Podarcis siculus radovanovici, Podarcis siculus ragusae, Podarcis siculus salfii, Podarcis siculus samogradi, Podarcis siculus sanctinicolai, †Podarcis siculus sanctistephani, Podarcis siculus siculus, Podarcis siculus tyrrhenicus, Podarcis siculus vesseljuchi.
Rapid adaptation
In 1971, ten adult specimens of Podarcis siculus were transported from the Croatian island of Pod Kopište to the island Pod Mrčaru, where the lizards founded a new bottlenecked population. The two islands have similar size, elevation, microclimate, and a general absence of terrestrial predators and the P. siculus expanded for decades without human interference, even out-competing the Podarcis melisellensis population. In the 1990s, scientists returned to Pod Mrčaru and found that the lizards currently occupying Mrčaru differ greatly from those on Kopište. While mitochondrial DNA analyses have verified that P. siculus currently on Mrčaru are genetically very similar to the Kopište source population, the new Mrčaru population of P. siculus was described as having a larger average size, shorter hind limbs, lower maximal sprint speed and altered response to simulated predatory attacks compared to the original Kopište population. These population changes in morphology and behavior were attributed to "relaxed predation intensity" and greater protection from vegetation on Mrčaru. In 2008, further analysis revealed that the Mrčaru population of P. siculus have significantly different head morphology and increased bite force compared to the original Kopište population. This change in head shape corresponded with a shift in diet: Kopište P. siculus are primarily insectivorous, but those on Mrčaru eat substantially more plant matter. The changes in foraging style may have contributed to a greater population density and decreased territorial behavior of the Mrčaru population. Another difference found between the two populations was the discovery, in the Mrčaru lizards, of cecal valves, which slow down food passage and provide fermenting chambers, allowing commensal microorganisms to convert cellulose to nutrients digestible by the lizards. Additionally, the researchers discovered that nematodes were common in the guts of Mrčaru lizards, but absent from Kopište P. siculus, which do not have cecal valves. The cecal valves, which occur in less than 1 percent of all known species of scaled reptiles, have been described as an "adaptive novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards".
