Italian wall lizard

Subspecies and hybridization P. siculus contains dozens of subspecies. Podnar et al. (2005) described 6 groupings of P. siculus in the species' native range. The first clade is the Sicula clade, which includes Southwestern Calabria, Sardinia, and Sicily. The Monesterace clade includes the Istrian coast. The Cantazaro clade includes central Calabria. The Tuscany clade spans across Western Italy. The Suzac clade includes islands in southern and central Dalmatia. The final clade is the Campestris-sicula clade, which spans Northern Italy and the Adriatic Islands inhabited by P. siculus. There have also been reports of hybridization between P. siculus and other species of the Podarcis genus, such as P. tiliguerta and P. raffonei. "Island syndrome" and sources of phenotypic variation Given the sheer number of subspecies of P. siculus and its vast geographic range, the evolutionary history of this species has been studied as case studies for certain evolutionary concepts. One such concept is "island effects," purported expansions of phenotypic range due to the availability of new niches. The evidence for island effects in reptiles, and lizards in particular, is not uniform or cohesive. A study evaluated the evidence of island effects among 30 island and 24 mainland populations of P. siculus for variation in head shape, size, and sexual dimorphism. Most of the disparities between sizes of individuals were explained by sexual dimorphism, though a low, but significant amount of centroid size variation could be attributed to being from a mainland versus an island population. Generally, individuals from island populations were smaller and had less sexually dimorphic body sizes. There was no connection between insularity and head shape sexual dimorphism, however insular head sizes were on average lower. These results complicate how P. siculus fits in with the island syndrome hypothesis, which posits that body and head sizes should be higher in insular populations. However, the island syndrome hypothesis also predicts a reduction in sexual dimorphism among insular populations, which was observed. == Physical description ==

The snout–vent length of P. siculus is on average. P. siculus is characterized by a green or brown back with a white or green belly. There is variation in length and color diversity due to the many subspecies and populations of P. siculus. For example, some subspecies are melanic, meaning that parts of the back and belly have hints of blue. Such coloration is found on island populations of P. siculus rather than continental populations. Head size is a sexually dimorphic trait, with males having larger heads and stronger jaws than females. It is hypothesized that this size difference is due in part to prey consumption needs in males and male–male aggression. == Range ==

True to its name, P. siculus is native to Italy and is one of the most common lizards there. The species seems to be extending its range from an initial colonization event in western Long Island, presumably by using railroad tracks as dispersal corridors along the middle East Coast. Wall lizards seem to have colonized along the southwest Connecticut coast near Greenwich, as well as around Burlington County, New Jersey. There are some reports that these lizards descended from a group of lizards released in Mount Laurel in 1984. In 2020, a large number of P. s. campestris entered Great Britain as stowaways among shipments of grapes, before being intercepted. P. siculus has also entered the Iberian Peninsula as an invasive species where it competes with the native Podarcis virescens species. Competition between the two lizard species has led to displacement of P. virescens lizards as they are outcompeted by P. siculus lizards. ==Habitat and ecology==

P. siculus is a habitat generalist and thrives in many natural and human-modified environments. Habitats of P. siculus include forests, grasslands, shrublands, rocky areas, and farmland. Plant matter comprises a much greater percentage of the diet of P. siculus than other related lizards. There is also a disparity in diet diversity between the sexes, with males having a more diverse diet than females. Contrary to common ecological thought, there is little relationship between habitat area and diet diversity for P. siculus. Different levels of taxonomic prey diversity does not seem to affect the diversity of diets in different P. siculus populations, but insular populations of P. siculus do consume a greater percentage of plant matter as a part of their diet. Reproduction P. siculus is oviparous. Females can lay 3 or 4 clutches of 4-7 eggs per year. The number of eggs laid per clutch does vary by population. For example, populations on small islands of Croatia lay fewer eggs that hatch into larger offspring. Disease Parasites and bacteria are common among P. siculus and its various subspecies. Common bacterial species include Pantoea, Citrobacter, Morganella morganii, Pseudomonas aeruginosa, Coagulase-Negative Staphylococci, Enterobacter, E. coli, Schewanella, and Providencia. When tested, one out of ten isolated strains of Citrobacter were multidrug-resistant. Other isolated strains were antibiotic resistant as well. The two islands have similar size, elevation, microclimate, and a general absence of terrestrial predators == Behavior ==

Feeding P. siculus has a strong preference for the consumption of non-conspicuous prey. Conspicuous coloration is a strong deterrent of consumption of carabid beetles. When consuming aposematic prey, P. siculus throws its head back and rubs its snout on the soil. Such behavior has been attributed to the unpalatability of aposematic prey. P. siculus is able to respond to chemical cues from some species of carabid beetles, evidence that the lizard has evolved to be able to detect the presence of dangerous chemicals in its prey. Learning Multiple experiments confirm the ability of P. siculus to learn a variety of different tasks. P. siculus can be trained to remove colored caps from food-containing pods. However, there is controversy over the ability of P. siculus to perform quantitative discrimination tasks. One experiment found that while 60% of subjects were able to distinguish between 1 and 4 items, very few were able to distinguish between 2 and 4 items, and none were able to distinguish between single objects with different surface areas. Additionally, a study has found that the more aggressive individual in a dyad spends more time basking than its less aggressive opponent. This relationship is prolonged: the individual that is more aggressive in a dyadic (one on one) encounter can make continued use of a thermally favorable environment over a long period of time. These more aggressive individuals grow faster than their less aggressive counterparts. In lizard dyads with low levels of aggression, there were smaller disparities between time spent basking. In such pairs, the two individuals may spend significant periods of time basking together. Regardless of aggression level in an initial encounter, this type of relationship was maintained between the dyad over a long period of time, demonstrating that social behavior is established quickly. However, basking behavior in isolation seemed to be replicated in the aftermath of these social encounters as well, suggesting that the relationship between sociality and basking depends on a more nuanced basis than behavior during an initial encounter. Anti-predatory P. siculus is able to detect chemical cues of common predators and modify its behaviors appropriately. P. siculus is also able to distinguish between scents of dangerous snakes and non-dangerous snakes. Studies have shown that P. siculus increase tongue-flicking behavior, commonly associated with stress, when exposed to predator scents. Similarly, experiments show that running behavior, tail-vibrating behavior, starting behavior, and stationary behavior all increase when P. siculus is exposed to predator scents than in control trials. Sudden, unpredictable starts may be more difficult to detect. Tail-waving may deflect attention of predators from the body of P. siculus to its tail. P. siculus can learn a training direction when operating under white polarized light with the direction of the electric field parallel to the training axis. Under blue and cyan light, P. siculus is able to correctly orient itself under polarization axes both parallel and perpendicular to the training axis. Red light polarization completely disoriented P. siculus under experimental conditions. Additionally, there is evidence that P. siculus has a time-compensated celestial compass. The time-compensated mechanism does not seem to be affected by whether or not the sun is in view. Effect of habitat on behavior A 2005 study compared seasonal and diel behaviors of an introduced population of P. siculus to its Italian counterparts. The activity period of P. siculus campestris was reduced compared to P. siculus in Rome, where lizards are active year-round. Colder mean temperatures in the New York habitat of P. siculus campestris may explain why this population's activity is limited to the months of April through October. P. siculus campestris was also active for fewer hours during the day compared to its Roman counterparts. The photoperiod of Long Island, New York, the home of P. siculus campestris, is similar to that of Rome. This similarity strengthens the argument for temperature explaining the discrepancy in activity levels. == Conservation status ==

The Italian wall lizard is listed as being of least concern by the International Union for Conservation of Nature (IUCN) on the IUCN Red List. Gravid females exposed to pesticides also lay larger, worse-quality eggs than control gravid females. Hatchling locomotion ability does not seem to be affected by maternal pesticide exposure. Also, it was found that some commonly used agricultural pesticides are either not neurotoxic to P. siculus or that the organism is capable of resisting the studied chemical's neurotoxicity, and that the P. siculus immune system was not significantly affected by the studied pesticides. ==See also==