Mirrored images but not silicone models trigger aggressive responses in male common wall lizards

Disentangling the effects of single releasers in animal communication is a demanding task because a releaser often consists of a combination of different key stimuli. Territorial communication in reptiles usually depends on visual, chemical, and acoustic stimuli, but the role of each of them depends on phylogeny. Lacertids are modern lizards that rely mainly on chemical cues for their communication, but they also use aggressive displays based on visual recognition. We experimentally tested the visual stimuli that release an aggressive response in the males of a typical lacertid, the common wall lizard (Podarcis muralis), testing the effects of silicone models and mirrored images in captivity. The response to models and control (a blank sheet) was not significantly different and these stimuli did not release any aggressive behaviour. On the contrary, the reflected image in a mirror caused overt aggression (i.e., bites against it) in 63% of tested individuals. The results clearly demonstrate the role of visual stimuli in territorial communication, but only as a combined effect of shape and motion, differently from other lizard families for which shape is enough to stimulate aggre sive responses. Mirrors can be useful tools to investigate aggression related to physiological and morphological aspects in lacertid lizards

First observation of convergent character displacement in a syntopic community of two italian lizards: Podarcis muralis and P.siculus

The co-occurrence of the lizards Podarcis muralis and P. siculus is frequent but anecdotally reported in the literature, mostly as side notes of their complex ecology and life history. There are a few studies on the interactions between these two species, but these are old or focalized only on individual populations. This research aims to fill and enlighten the possible competitive interactions between P. muralis and P. siculus when they share a microhabitat. Being a base research, which is not founded on previous works, every result will be an important contribution to the study of these two lizards. We have observed a clear trend in P. muralis associated with the elongation of the jaw in the syntopic population of Calci, while their body size remains unchanged between syntopic and allopatric populations. This differentiation causes an overlap in jaw length between the two species and the sharing of the same range of variation for this character. Hence, in syntopy, they are not distinguishable at all if we base our discrimination only on the length of the jaw, contrary to the common situation where P. siculus head-length outmeasures P. muralis. Syntopic P. muralis are instead well discriminable from their allopatric populations. For the first time, we provide comparative data from different populations, both in allopatry and in syntopy. Our preliminary results suggest a diversification only in head morphology (convergent character displacement) in the area of co-occurrence, hence a proxy of a history of co-evolution that shape the relationship of these two species

The exposition to urban habitat is not enough to cause developmental instability in the common wall lizards ( Podarcis muralis )

Developing trustworthy biomarkers is of primary importance in monitoring impacts of environmental stressors on biological systems. Recently, fluctuating asymmetry in morphological traits of the common wall lizard (Podarcis muralis) has been proposed as useful tools for assessing environmental disturbance in urban habitats. However, the experimental design used in previous studies lacked both site replication (only one urban area was sampled) and independent assessment of the physiological conditions of lizards. Hence, we replicated the analysis involving three large cities in Northern Italy and measured lizards’ health conditions as assessed by blood sampling analyses. We found a weak statistical association between fluctuating asymmetry and urban habitat. No significant differences occurred for white blood cell concentration and heterophils-to-lymphocytes ratio, whereas parasite load was significantly lower in urban than natural populations. Finally, somewhat of the variability in fluctuating asymmetry correlated with one or more latent variables not directly observed, but still not related to the habitat. Contrary to previous studies, we concluded that fluctuating asymmetry cannot be regarded as a reliable measure of urban environmental stresses. Despite this, fluctuating asymmetry in the morphology of common wall lizards has a real potential for working as biomarkers, but we need to clarify first the developmental mechanisms, the true effectors of the stress, their interactions and their effects on individual fitness in order to solve the inconsistencies occurring among different studies

The Italian wall lizard, Podarcis siculus campestris, unexpected presence on Gorgona Island (Tuscan Archipelago)

We here report the unexpected presence of the Italian wall lizard (Podarcis siculus campestris) on Gorgona Island, in the Parco Nazionale Arcipelago Toscano (Tuscan Archipelago, Tyrrhenian Sea, Tuscany, Central Italy). Field observations were carried out in 2020 confirming its presence on the island, where it had never been reported before. We recorded 37 GPS points of the species in three major areas of Gorgona (with 50 lizard records) and about 180 visual counts regarding all age classes (newborns, juveniles and adults). The species was found in the urban area (site of state prison) and in two grassy and bushed areas, around and along olive tree plantations. Seven individuals were captured and their tails were used to assess the sequence variation of the mitochondrial CYB gene. Biometrical parameters were also evaluated for six of these individuals. We detected three distinct CYB haplotypes that were compared to Podarcis siculus CYB sequences available in public databases. They resulted identical or phylogenetically closest to those found in mainland Tuscany. One haplotype, found in three specimens, was identical to one previously detected at Orti Bottagone (WWF Oasis in Piombino), while the other two haplotypes were most similar to haplotypes reported in the Giannella peninsula and Pisa, respectively