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In: Amphibia-Reptilia
In: Amphibia-Reptilia
In: The Romantic Stage
Authors: Marco Zuffi and Claudia Corti

Abstract

Hermann's tortoise (Testudo hermanni Gmelin) of the Island of Asinara (NW Sardinia, Italy) has been studied during a period of four seasons. This population consisted of several individuals of large body size, some of them being amongst the largest known for this species. Bony shells of males were commonly found on this island, while the same was not true for female bony shells. Although wild boars (Sus scrofa) are potential large sized predators for tortoises, the analysis of carapace morphology did not reveal injuries signs due to bites. Male tortoises could die due to up-turning, as the result of male-male combats during the mating season, to possible hyperthermia when upturned, and to predation carried out by birds particularly when upturned. Estimated density was 4.88 individuals ha-1, which was similar to that of conspecifics from other areas studied so far.

In: Amphibia-Reptilia

Human activities cause increasingly deep alterations to natural environments. Yet, the effects on vertebrates with low dispersal capacity are still poorly investigated, especially at field scale. Life history variation represents one means by which species can adapt to a changing environment. Among vertebrates, lizards exhibit a high degree of variation in life-history traits, often associated with environmental variability. We examined the female breeding output of Podarcis siculus (Lacertidae) inside agricultural habitats, to test whether different cultivation and management influence the life-history traits of this species. Interestingly, we recorded variability of female breeding output at a very fine scale, namely among adjacent vineyards and olive orchards under different management levels. Lizards displayed the lowest breeding effort in the almost unmanaged sites, while clutch mass, relative fecundity and mean egg mass slightly increased in more intensively managed sites. However, in the most intensive cultivations we detected a life-history trade-off, where eggs from larger clutches tended to be relatively smaller than eggs from smaller clutches. This pattern suggests that agriculture can influence lizard reproductive output, partly favouring it in the presence of medium intensity cultivation but causing, in the most intensively managed sites, some environmental constraints that require a peculiar partitioning of the breeding resources. Even though further studies are needed to clarify the mechanisms driving the observed pattern, our results can be considered a starting point for evaluating the analysis of lizard breeding features as a tool to assess the impact of human activities, at least in agricultural environments.

In: Animal Biology

Abstract

Two adult Podarcis muralis whose normal movements incorporated the flat top of a wall, frequently paused so that they were looking outwards from an edge ("scan" posture), especially during longer (≥9 s) periods immobile. Investigations of the posture on raised wooden platforms in outdoor enclosures, using two juvenile lizards, showed that (1) lizards spent significantly more time on platforms than would be expected from random movement, and this was not because wood is a favoured substrate for basking; (2) lizards which were immobile on platforms spent significantly more time at edges than would be expected by chance; (3) body orientations at 67.5-112.5° to the edge were the most frequent and these were maintained for significantly longer periods than the remaining orientations; exceptions were from 0800-0900 h when orientation was often parallel to the edge facing the sun and from 1200-1300 h with only a thin strip of shade at 45°, into which the lizards fitted themselves. Lizards basking in the laboratory beneath a tungsten bulb at the edge of a raised platform adopted outward-facing orientations when the platform height was ≥6 mm. When presented with a choice between basking more effectively (i.e. rapid heating rate) or adopting the "scan" posture at an edge with a lower heating rate or with no heating, they opted for the former. Podarcis sicula, P. filfolensis, Lacerta viridis and L. vivipara all showed an excess of outward-facing orientations when the basking bulbs were place near edges of platforms, but Psammodromus hispanicus did not. Only the two Podarcis species, however, spent more time on raised platforms than would be expected by chance when basking was possible at many sites in an arena.

In: Amphibia-Reptilia

Abstract

Human agricultural activities can deeply alter the environment thus provoking major impacts on a variety of organisms. Agricultural habitats however can be very different from one another in terms of habitat structure and management intensity, presenting varying pressures and/or benefits for different species. Agro-ecosystems can have opposing effects on reptiles and in some circumstances the presence of a species can even been enhanced by agricultural practices. We focused our study on Podarcis sicula, a relatively widespread lacertid lizard commonly present in agro-environments in Italy. We examined escape behaviour, caudal autotomy rates and ectoparasite load (tick infestation) in populations living in two different land uses, olive tree plantations and vineyards. All three aspects seemed to be deeply influenced by habitat structure. Predation pressure, as evaluated by tail break frequency, was lower in olive tree plantations, the most structurally complex habitats. In this type of habitat lizard escape behaviour was characterised by a clear preference for olive trees as refuges: individuals ran farther distances on average to reach the trees and hid inside them for a relatively long time. In vineyards, on the contrary, a less clear escape strategy was observed, showing a use of more temporary refuges. Also tick (Ixodes ricinus) infestation differed among land uses, being higher in olive tree plantations, probably in relation to vegetation cover features. Differences were found also between managements (with a higher tick load in traditional cultivations) and sexes, with males being more parasitized.

In: Amphibia-Reptilia

Sex-biased differences in dietary habits of snakes are often linked to pronounced sexual size dimorphism in absolute body size or in relative head size. We studied the food habits of free-ranging forest cobras (Naja melanoleuca) in southern Nigeria to find whether any intersexual dietary divergence is present in this species, and measured both museum vouchers and free-ranging specimens to find whether any intersexual divergence in relative head size is present. We demonstrated that: (1) head sizes increases more rapidly with SVL in females than in males, with a result that, at the same body length, the females tended to have significantly larger heads; (2) males and females were nearly identical in dietary habits, both if we consider prey size or prey type; (3) both sexes tended to prey upon relatively little sized preys. It is concluded that traditional evolutionary scenarios for explaining sexual dimorphism and food niche divergence are hardly valid in this case, and we need to look for entirely different hypotheses (e.g. linked to the sexual preference of males for females with larger heads).

In: Contributions to Zoology

Abstract

Abstract. The horseshoe snake (Coluber hippocrepis) is one of the most threatened Italian snakes, especially in Sardinia where its present occurrence was unclear. This paper reviews the current distribution of C. hippocrepis in Sardinia, and confirms that this species is still found in a limited number of sites of Cagliari province. Its actual presence in Oristano province, on the contrary, is still in doubt. Statistical analyses on several morphometric measurements taken from museum specimens suggest that snakes from the central Mediterranean area (Sardinia, Pantelleria, and Tunisia) are distinguished from those of the western Mediterranean area (Portugal and Morocco) by having significantly higher numbers of ventrals. A few natural-history notes on Sardinian specimens are presented, and a rationale for an urgent conservation plan is given.

In: Amphibia-Reptilia

Abstract

Using mtDNA sequences and 12 microsatellite loci, we compare populations of Testudo graeca from Sardinia and North Africa. The observed pattern of almost no differentiation combined with reduced variation in the Sardinian population is consistent with introduction in prehistoric or historic times from what is now Tunisia and neighbouring Algeria. Furthermore, in the light of the recently published recommendation to eradicate the non-native T. graeca from Italy, we review recent studies on the archaeological and fossil record, on the phylogeography and population genetics of the three other chelonian species occurring in Sardinia (Emys orbicularis, T. hermanni, T. marginata). We conclude that the extant Sardinian populations of all four species are not native. However, they are and should be safeguarded under EC law (Council Regulation No 338/97 on the Protection of Species of Wild Fauna and Flora; Flora Fauna Habitat Directive: Appendix IV, Art. 12) because they serve as a back-up for the declining mainland populations. Moreover, these populations constitute an important part of the human-shaped natural heritage of the Mediterranean.

In: Amphibia-Reptilia