Wall Lizard Podarcis Muralis Research Articles

Sex-specific predation on two lizard species by kestrels

Sex-biased predation is thought to have important implications for sexual selection, sex allocation, and population dynamics (Magnhagen, 1991; Le-Galliard et al., 2005 for an example in lizards). Most studies found that males are subjected to higher predation pressure than females during the reproductive season (Korpimaki, 1985; Lode et al., 2004; Christe et al., 2006; Costantini et al., 2007). In that period, males are very mobile, emit acoustic signals and exhibit brilliant colourations, which are needed to attract females but may make them more visible to predators. With regard to lizards, a recent study provided the first evidence that males of a lizard species may be preyed on more than females (Costantini et al., 2007). In the present study, we investigated whether there is sex-biased predation on two small lacertid species, the common wall lizard Podarcis muralis (Laurenti, 1768) and the Italian wall lizard Podarcis sicula (Rafinesque-Schmaltz, 1810), by Eurasian kestrels (Falco tinnunculus) during the reproductive season. We also examined whether (1) the rate of predation differed between species and (2) the rate of predation differed across years or among hunting habitats for each species.

Male–male combats in a polymorphic lizard: residency and size, but not color, affect fighting rules and contest outcome

Theoretical models predict that the outcome of dyadic agonistic encounters between males is influenced by resource-holding potential, resource value, and intrinsic aggressiveness of contestants. Moreover, in territorial disputes residents enjoy a further obvious competitive advantage from the residency itself, owing to the intimate familiarity with their territory. Costs of physical combats are, however, dramatically high in many instances. Thus, signals reliably reflecting fighting ability of the opponents could easily evolve in order to reduce these costs. For example, variation in color morph in polymorphic species has been associated with dominance in several case studies. In this study, we staged asymmetric resident-intruder encounters in males of the common wall lizard Podarcis muralis, a species showing three discrete morphs (white, yellow, and red) to investigate the effects of asymmetries in color morph, residency, and size between contestants on the outcome of territorial contests. We collected aggression data by presenting each resident male with three intruders of different color morph, in three consecutive tests conducted in different days, and videotaping their interactions. The results showed that simple rules such as residency and body size differences could determine the outcome of agonistic interactions: residents were more aggressive than intruders, and larger males were competitively superior to smaller males. However, we did not find any effect of color on male aggression or fighting success, suggesting that color polymorphism in this species is not a signal of status or fighting ability in intermale conflicts.

Lateralization in the predatory behaviour of the common wall lizard (Podarcis muralis)

Ectotherms have been shown being lateralized as well as mammals and birds. This is particularly evident in visual lateralization, i.e. the different use of the eyes, leading to use a specific eye to observe specific kind of stimuli and to process them with the correspondent contralateral hemisphere. Several lower vertebrates are facilitated in this from the lateral position of the eyes, enabling them to carry out more tasks simultaneously, controlled by different eyes and relative hemispheres. Predatory responses seem usually mediated by the right eye/left hemisphere in fishes, amphibians and some sauropsids, but there are no strong evidences of this in lizards. Eighteen wild males of the Common wall lizard Podarcis muralis were tested individually in captivity to ascertain whether they are lateralized to look at prey with a specific eye. The lizards were gently induced entering a 30-cm long central arm of a T-maze which led to a 44.5-cm long arm cross-arm at whose extremities there were two identical prey, Tenebrio molitor larvae, familiar to the lizards. We recorded what direction the lizards chose to reach the prey and the frequency and duration of head turning, indicative of looking either prey with the left or the right eye. We found that individuals show being lateralized at individual level. The preferred direction taken to reach the prey is the right for the majority of those (4 of 5) showing an evident preference, indicating also a possible form of laterality at population level. In addition, lizards maintained the same head side of the direction taken turned for more time towards the prey than the opposite head side, revealing an eye preference for observing this kind of cue. Our study demonstrates how males of Podarcis muralis have a visual lateralization to capture prey. Furthermore, it is another support to the hypothesis of vertebrate lateralization derivation from a common ancestor.

Do demographic aspects of neighbouring lizard populations differ? A case study with the common wall lizard, Podarcis muralis

AbstractDemographic and morphological aspects of two nearby subpopulations of the common wall lizard (Podarcis muralis) were studied, by a capture-mark-recapture procedure, at an archaeological site in the surroundings of Rome, central Italy. In both sites, the births peak was observed in September. Adult sex-ratio was skewed towards males in one subpopulation, but was close to equality in the other. Morphological characteristics were consistent in the two sites, with males always exhibiting larger snout-vent-length and head size. Population size and density, computed by a Jolly-Seber index applied by using POPAN model revealed differences between subpopulations, with lizard density being much higher in the site with higher habitat heterogeneity and shelter availability. Tail condition was similar between sites. The general implications of these data are discussed.

The selective basis for increased egg retention: early incubation temperature determines hatchling phenotype in wall lizards (Podarcis muralis)

The thermal environment during development influences many aspects of the phenotype of hatchling reptiles. We hypothesized that temperature should differentially affect early incubation stages, in which differentiation dominates over growth, and late incubation stages, characterized by high growth rates. To test this idea, we incubated eggs of wall lizard (Podarcis muralis) under three regimes with the same mean temperature (29 °C), one constant and two variable with opposite sequences: first cold (25 °C) and then hot (32 °C), and vice versa. Hatchlings incubated at high temperature during the initial period had shorter hindlimbs and tails than those incubated under the other two temperature regimes and shorter heads than those incubated initially at low temperature. Thus, temperature experienced by embryos during the early external incubation period produced similar phenotypic responses compared to those reported in previous studies for the same constant temperature applied over the whole incubation period. Because female wall lizards select lower body temperatures during pregnancy, an increase of intrauterine retention would extend the time of exposure of developing embryos to suitable temperatures. Diminution of body temperature during pregnancy is contrary to the expected pattern under the hypothesis that egg retention has evolved to accelerate development, as proposed by the cold-climate model for evolution of viviparity in squamates, and the results of the present study support the alternative hypothesis of developmental optimization as a special case of the broader maternal manipulation view. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 441–447.

Microgeographic variation of colour morph frequency and biometry of common wall lizards

AbstractThe throat and belly of both sexes of the common wall lizard Podarcis muralis exhibit a polymorphic coloration with three morphs (white, yellow and red). We documented the occurrence of this polymorphism in 11 populations of northern Italy, and investigated the morphometric features of the three morphs in both sexes. The white morph was more frequent (56.6%), while yellow and red morphs accounted for 28.7 and 14.7% of the lizards, respectively. Moreover, the red morphotype was more frequent among males while the white one was more frequent among females. The occurrence of the three morphs varied microgeographically from populations with a higher proportion of white individuals to those where all morphs were more equally represented. The comparisons of morphometry between morphs did not reveal any significant difference among males, while snout–vent length and head height in females increased from the white‐throated to the yellow‐throated morph, and from the yellow‐throated morph to the red‐throated one. Possible functions of this polymorphic coloration are discussed.

Promiscuity and high level of multiple paternity in common wall lizards (Podarcis muralis): data from microsatellite markers

AbstractLittle is known about the mating system of the common wall lizard Podarcis muralis. Behavioural and observational data have demonstrated that females frequently mate with multiple males. However, the possible occurrence of multiple paternity has never been investigated. By using microsatellite paternity analysis in a wild population, we document this species indeed mate promiscuously and these matings resulted in multiple paternity in at least 87% of the clutches examined.

The Numerical Encoding of Scale Morphology Highly Improves Photographic Identification in Lizards.

Photographic identification is a promising marking technique alternative to the toe-clipping, but is time consuming, particularly when a large number of individuals is involved. For this reason several authors had frequently preferred the toe-clipping. In this study we analysed the black spot pattern of ventral scales of wall lizards (Podarcis muralis) and we showed that photographic identification is an effective method for recognizing individuals, and the error of this technique is much less than that of the toe-clipping arising from natural toe loss. Moreover, the numerically encoding of the black spot pattern may radically reduce the time needed to compare the pictures of large samples of individuals, solving one of the more important obstacle against the use of photographic identification.

The feasibility of using introduced lizards as indicators of environmental contamination

Introduced species can provide valuable opportunities for applied research once they have become established with little possibility of eradication. They have been used as indicators of environmental contamination in aquatic ecosystems for many years. However, in terrestrial ecosystems, introduced species have not been utilized as sentinels of environmental quality. We review the feasibility of using species of lizards that have been introduced, are closely related to species that have been introduced, or have the potential of being introduced to the United States, as indicators of heavy metal contamination. Metal concentrations in lizards were compared from the few available studies, including one recently conducted on the introduced brown anole Anolis sagrei in southern Florida. Brown anoles, tropical house geckos Hemidactylus mabouia, sand lizardsLacerta agilis, common viviparous lizards Lacerta vivipara, common wall lizards Podarcis muralis, and starred agamas Laudakia (Agama) stellio stellio were shown to be suitable indicators of heavy metal pollution because differences were found in metal levels in lizards from different locations within a given region, and lizards from sites presumed to be contaminated by heavy metals contained higher metal concentrations than those from locations that were uncontaminated.

Feeding strategies of Elaphe longissima from contrasting Mediterranean habitats in central Italy

A 17‐year study on the diet composition of the snake Elaphe longissima was carried out in three contrasting Mediterranean habitats in central Italy: an agro‐forest habitat, a thick forest habitat, and a bushy pasture habitat. In the agro‐forest area, the snake diet consisted only of small mammals and lacertid lizards, but in the other two areas also of birds and their eggs. There were significant differences of prey eaten by snakes among habitats: a UPGMA tree diagram clustered the agro‐forest and the thick forest habitats, whereas the bushy pasture habitat proved to be very different from the other two. Lizards were preyed mainly in the agro‐forest habitat. Species of the family Muridae (and in particular the wood mice Apodemus sp.) were preyed upon considerably more frequently than Microtidae in all habitats. Among the birds, only some species of the order Passeriformes were preyed upon, and among the reptiles, wall lizards Podarcis muralis were preyed upon more frequently than any other species. Diet composition was similar in males and females. There was a positive relationship between log‐transformed prey size (mass, in g) and predator size (mass, in g) in all the studied habitats, and the regression lines relative to the various habitats did not differ significantly in terms either of slope or elevation. A model of ANOVA treatment revealed that the snakes of the three habitat types were similar both in terms of absolute body size (mass in g) and residuals of the ‘predator size‐prey size’ regressions.

The influence of thermal and hydric environments on embryonic use of energy and nutrients, and hatchling traits, in the wall lizards ( Podarcis muralis)

Among (different) clutch variation in egg composition, influence of thermal and hydric environments on incubating eggs, embryonic use of energy and nutrients, and hatchling traits were studied in the wall lizard Podarcis muralis from a lowland population of Northern Spain. When initial egg mass was kept constant, we found that some measured egg variables such as water, lipid-free organic material, ash, calcium and magnesium in egg contents, and ash and magnesium in eggshell, remained remarkably constant, whereas other variables differed considerably among clutches. All viable eggs increased in mass over the course of incubation due to absorption of water, and mass gain during incubation was dependent on initial egg mass, temperature and substrate water potential. Variations in the wet mass of hatchlings among treatments stemmed mainly from variations in water content. Hatching success, embryonic use of energy and nutrients, and sex, size and mass of hatchlings were unaffected over a wide range of substrate moisture. The incubation length decreased as temperature increased. However, the effect of substrate moisture on duration of incubation varied with temperature. The influence of incubation temperature on the snout-vent length of hatchlings, if present, was very weak. Incubation temperatures did not affect the sex ratio and carcass dry mass of hatchlings, but significantly affected the tail length of hatchlings, with individuals from the highest temperature having the shortest tails. The energy expenditure of embryogenesis during incubation remained remarkably constant among treatments, and energy reserves in the hatchling were largely dependent on allocation of energy materials in eggs. A high incidence of dead-in-shell embryos occurred in eggs that were laid in June and, thereafter, when ambient temperatures were high. Deformed hatchlings were distributed nearly equally among treatments.

Home Range Ecology of an Introduced Population of the European Wall Lizard Podarcis muralis (Lacertilia; Lacertidae) in Cincinnati, Ohio

-A 2-yr field study of introduced wall lizards, Podarcis muralis, revealed a resident population which remained remarkably stable (n = 37 lizards for each year). Slightly more than half of the 167 wall lizards originally captured and marked disappeared from the study sites and were classified as nonresidents. Males occupied significantly larger home ranges than females and, in 1991, had higher instances of intersexual home range overlap than did females. Instances of female-female home range overlaps in 1991 were more numerous than corresponding overlap between males. There was no difference between the sexes with respect to mean percentage of home range overlap in 1990, but females exhibited greater percent overlap in 1991. Small home range size and high home range overlap suggest that the Cincinnati population may have switched from territorial behavior (reported for European populations) to a hierarchical dominance system, possibly in response to unique pressures (high lizard densities, high predation pressures and low availability of preferred habitat) in the Cincinnati area. We interpret our results in light of recent findings regarding lizard spacing patterns, optimality theory and predictions concerning introduced lizard populations. We also compare our data on one of the only successfully introduced lacertid lizards in North America to data from native European populations.

Annual Reproductive Cycle of an Introduced Population of European Wall Lizards (Podarcis muralis) in Ohio

The annual reproductive cycle of an introduced population of wall lizards was determined. Male lizards have a postnuptial pattern of testicular growth, with recrudescence beginning in August following a 1-2 month period of inactivity. Females exhibit ovarian growth following spring emergence and cycle until mid-July. Up to three clutches of 4-5 eggs each are oviposited annually. The timing of reproductive events is similar to that seen in lowland populations of wall lizards in Europe.

Ecologie trophique d’une population de lézards des murailles Podarcis muralis dans l’Ouest de la France

The feeding ecology of a population of the Wall Lizard Podarcis muralis was studied in the West of France from 1982 to 1983. The consumption and the availability of prey have been compared considering taxonomic categories and size classes. The wide taxonomic spectra, the great size range of ingested prey, and the important temporal variability of the diet stressed the opportunistic feeding behaviour of this species. However, a detailed comparison between the consumption and the availability of prey, and the comparison with another population (Mou et Barbault, 1986) reveal some degree of prey selection, which modulates the trophic opportunism characteristic of this species.