Michele Ghitti

Genetic and phenotypic component in head shape of common wall lizard Podarcis muralis

Head shape in lizards correlates with a wide range of environmental pressures, supporting the hypothesis that patterns of phenotypic change represent adaptive responses to selective processes. However, natural selection promotes evolutionary adaptation only if the trait under selection has enough heritable variation. In this study we used geometric morphometrics and quantitative genetics to assess the heritability patterns of the head shape and size of common wall lizards ( Podarcis muralis ). Genetic and phenotypic components were estimated using animal models, which showed that more than half of the variation in head morphology is inheritable. Furthermore, at least five independent patterns of genetically determined phenotypic change were detected. These outcomes confirm that morphological differentiation in common wall lizards may reliably be regarded as the result of adaptive processes driven by natural selection.

Effects of Different Temperatures on the Development of Dermestes Frischii and Dermestes Undulatus (Coleoptera, Dermestidae): Comparison Between Species

Dermestidae could be useful in forensic investigations to assess the PMI as adults and larvae colonize dried remains. We reared two species of Dermestidae (Dermestes frischii and Dermestes undulatus) to understand the effects of different temperatures on the length of their whole life cycle and on their immature stages. Both species were reared at 23°C ± 0.5, RH 75% and at 26°C ± 0.5, 75% RH. Our result shows that the temperature is the main factor that influences the development of those species; in fact, increasing temperature leads to a shorter development cycle (59.8 ± 0.5 and 38.1 ± 0.2 for D. frischii; 50.6 ± 0.6 and 36.2 ± 0.2 for D. undulatus). Furthermore, we found that the number of the molts before the pupa decreases from 5–7 to 5–6 for D. frischii and from 4–6 to 4–5 for D. undulatus, respectively, at 23°C and 26°C.

MRI evaluation of sacral chordoma treated with carbon ion radiotherapy alone

BACKGROUND AND PURPOSE To compare RECIST 1.1 with volume modifications in patients with sacral chordoma not suitable for surgery treated with carbon ions radiotherapy (CIRT) alone. To evaluate patients pain before and after CIRT. To detect if baseline Apparent Diffusion Coefficient values (ADC) from Diffusion Weighted sequences could predict response to treatment. MATERIAL AND METHODS Patients included had one cycle of CIRT and underwent MRI before and after treatment. For each MRI, lesion maximum diameter and volume were obtained, and ADC values were analyzed within the whole lesion volume. Patients pain was evaluated with Numerical Rating Scale (NRS), considering the upper tumor level at baseline MRIs. RESULTS 39 patients were studied (mean follow-up 18 months). Considering RECIST 1.1 there was not a significant reduction in tumor diameters (p = 0.19), instead there was a significant reduction in tumor volume (p < 0.001), with a significant reduction in pain (p = 0.021) if the tumors were above vertebrae S2-S3 at baseline MRIs. The assessment of baseline ADC maps demonstrated higher median values and more negative skewness values in progressive disease (PD) patients versus both partial response (PR) and stable disease (SD). CONCLUSIONS Lesion volume measurement is more accurate than maximum diameter to better stratify the response of sacral chordoma treated with CIRT. Preliminary results suggest that baseline ADC values could be predictive of response to CIRT.

The effect of thinning and cue:density ratio on risk perception by Rana dalmatina tadpoles

The “risk assessment hypothesis” considers prey density as an important variable to properly assess the actual level of risk, and predicts that, when the ratio between predator cue concentration and prey density is constant, the level of risk perceived by prey is the same. All previous studies which tested this hypothesis with Anurans manipulated density by placing tadpoles into experimental tubs at fixed group sizes. As predation is a process that produces a progressive decrease in prey density, i.e. “thinning”, prey may respond to the rate of group size reduction rather than the absolute number of conspecifics in a given place at a given time. To test if Rana dalmatina tadpoles perceive the progressive decrease in population density due to predation and are able to use this information to fine-tune anti-predator responses, we combined thinning with a constant cue:density ratio and evaluated how these two types of information affected the level of activity of tadpoles. Our results showed no effect of density reduction on prey level of activity, and thinning did not interact with cue intensity to modify tadpoles’ behaviour. However, we observed no difference in tadpole behavioural responses between treatments with the same cue:density ratio.

Morph-specific assortative mating in common wall lizard females

Abstract Color polymorphism often is associated with alternative reproductive strategies and may reflect different adaptive optima that coexist within populations. The equilibrium among morph frequencies is maintained by the occurrence of opposite selective pressures (disruptive vs. stabilizing), which promote polymorphism while preserving gene flow. Sexual selection may contribute on both sides, particularly when morphs do not mate randomly. Reptiles offer a good model, notably lizards. Nevertheless, previous studies on mate choice in polymorphic lizards have generated contrasting results, with some studies suggesting that female morphs might tune their preference depending on environmental/social conditions such as crowding. We experimentally manipulated the number of individuals a female common wall lizard Podarcis muralis perceives around her, to test if females of different morphs (white or yellow) tune their choice for white and yellow males in order to maximize the probability that hatchlings follow the strategy best adapted to the population density. Results showed that crowding experienced by females did not affect mate choice, arguing against a flexible choice strategy by females. However, white females significantly associated with white males, whereas yellow females did not significantly associate with yellow males. Thus, sexual selection could contribute to the maintenance of color polymorphism in this species by a mix of assortative and non-assortative mating strategies, which could maintain the equilibrium between gene divergence and gene flow among morphs.

Effects of Colour Morph and Temperature on Immunity in Males and Females of the Common Wall Lizard

Colour polymorphism in reptiles is generally associated with the coexistence of alternative reproductive strategies that involve specific trade-offs among different life history traits. Notably, body temperature trades off with immunocompetence: temperature has relevant effects on immune-response, but maintaining the optimal temperature increases both energetic costs and predatory risk. This trade-off gains complexity by sex, since males and females could optimize fitness by different strategies. Given that there is no single solution for trade-offs, different links among alternative evolutionary stable solutions and morphs might evolve independently in each sex. We tested this hypothesis in the common wall lizard (Podarcis muralis) by means of in vitro cultures of blood cells in order to examine the response of the immune-system to phytohemoagglutinin stimulation in male and female morphs at two different temperatures (i.e. 22 and 32 °C), corresponding to the thermal optima of the two sexes. We found (i) morph-specific immunity in both sexes, i.e. yellow lizards suffer immunosuppression with respect to the other morphs, and (ii) sex-specific immunity under hot conditions, i.e. females of all morphs were immunosuppressed with respect to males. Results support the hypothesis that morphs might differently invest in immunocompetence, according to different set-up for the trade-offs between immunity and other life-history traits, resulting in alternative strategies with different fitness optima.