1,720,982 research outputs found
How many Archaeolacerta inhabit the Corso-Sardinian Plate? Allozyme variation and differentiation in Archaeolacerta bedriagae (Camerano, 1885)
No full textArchaeolacerta bedriagae is a rock lizard endemic to Corsica and Sardinia. Four subspecies have been recozied to date on the basis of morphological traits. Previous allozyme investigations revealed high genetic differentiation among populations of the species. Based on these results some authors hypothesized that more than one species of Archaeolacerta may occur on Corsica and Sardinia. In this paper we investigated allozyme variation at 19 gene loci in 5 populations belonging to all subspecies of A. bedriagae in order to study genetic differentiation among populations from Corsica and Sardinia, and to compare our results with those obtained in previous studies carried out on allozyme variation and taxonomy of the species. Low levels of genetic differentiation (average Nei's D = 0.026) and heterogeneity (mean F ST = 0.147) were found comparing the A. bedriagae populations, and there was no evidence of interruption or restriction of gene flow. This is in agreement with the available molecular and morphometric data, while it is not in accordance with allozyme data reported in the previous studies. Our data do not support the hypothesis of an unrecognized criptic species of Archaeolacerta in Corsica and Sardinia, and indicate that the definitive assessment of the taxonomic status of the A. bedriagae populations requires further investigation. © 2009 Koninklijke Brill NV, Leiden
Predicting elusiveness: Potential distribution model of the southern smooth snake, coronella girondica, in italy
No full textPredictive models of species distribution may be very useful for under-standing actual distribution of elusive species, including several snakes. The southern smooth snake (Coronella girondica) is likely the most elusive snake species of penin-sular Italy, and is therefore well-suited for predicting potential distribution studies. In this paper we predict the potential distribution map of this species in Italy by using MAXENT algorithm, that finds the probability distribution of maximum entropy that is constrained by considered ecological parameters. Presence data for Coronella girondica were gotten from CKmap. The potential distribution model of Coronella girondica showed a very good overall performance (AUC = 0.959), and indicated that high suitability areas correspond mainly to Tyrrhenian north and central regions, including Liguria, western Emilia-Romagna, Tuscany, Umbria, and northern Latium. Southern Italian regions were clearly unsuitable for this snake species. Overall, our study revealed that previous distribution maps indicating the occurrence of Coronella girondica in southern Italy and Sicily were poorly reliable. The conservation and management implications of our study are also addressed
Genetic variation and its evolutionary implications in a Mediterranean island endemic lizard
No full textThe peculiar bioclimatic and geographic features of Corso-Sardinian islands may provide an ideal scenario for investigating microevolutionary processes, given their large heterogeneity of environments, which could affect dispersal and gene flow among populations, as well as processes of local adaptation. The genetic variation and differentiation among populations of the endemic lizard Archaeolacerta bedriagae were studied by allozyme electrophoresis at 20 presumptive loci. The genetic structure of this species is characterized by relatively high levels of polymorphism and low differentiation among populations. The pattern of genetic differentiation cannot be explained by genetic drift as a function of geographic distance. Genetic distance data show that genetic variation is distributed into three geographically coherent population groups and suggest a recent (Late Pleistocene) origin for the observed geographic fragmentation. The analysis of environmental correlates of allozymic variation indicates a strong correlation of the Idh-1 locus with climatic variables. The frequency of the Idh-1 106 allele is negatively correlated with annual temperature, and positively correlated with annual precipitation. In addition, the observed heterozygosity at this locus decreases towards more arid climatic regimes. The results obtained support the assumption of differential selection acting on Idh-1 allozymes under diverse climates. An association between Idh-1 allozymes and local bioclimatic regimes was also observed for the sympatric lizard Podarcis tiliguerta, suggesting a key role for such selective agents on Idh-1 polymorphism in these two Corso-Sardinian lacertids. © 2009 The Linnean Society of London
Feeding habits of a Mediterranean community of snakes in relation to prey availability
No full textFood habits of four sympatric terrestrial snakes (Vipera aspis, Coluber viridiflavus, Elaphe longissima, Elaphe quatuorlineata) are studied in a forested area of the «Roman Country», about 15km northeast of Rome. All species proved to be extremely similar in food choice, preying primarily upon small mammals (rodents and shrews) and laccrtid lizards. Adult vipers occasionally preyed on brown frogs, while nestling birds were captured by all species (especially E. quatuorlineata) apart E. longissima. We estimated the relative density of several potential prey (all the small mammals and three of the lizard species), and found highly positive relationships between prey availability and prey use by snakes. Because of the high overlap between diets of the four snake species in the area, a strong interspecific competition may be predicted if the prey resource tends to declineLes habitudes alimentaires de quatre espèces sympatriques de serpents terrestres (Vipera aspis, Coluber viridiflavus, Elaphe longissima, Elaphe quatuorlineata) ont été étudiées dans une zone forestière de la «Campagne romaine », environ 15 km au nord-est de Rome. Toutes les espèces sont apparues extrêmement semblables quant à leurs choix alimentaires, capturant avant tout des petits mammifères (rongeurs et musaraignes) et des lézards (Lacertidés). Les vipères adultes capturent occasionnellement des grenouilles ; à l’exception d’E. longissima, toutes les espèces, et en particulier E. quatuorlineata, prennent des oisillons. La densité relative de diverses proies potentielles (tous les petits mammifères et trois espèces de lézards) a été estimée et une forte relation positive a été trouvée entre la disponibilité des proies et leur consommation par les serpents. En raison du fort recouvrement des régimes alimentaires des quatre espèces de serpents dans la zone d’étude, une forte compétition interspécifique apparaît prévisible en cas de diminution des proies.Capizzi Dario, Luiselli Luca, Capula Massimo, Rugiero Lorenzo. Feeding habits of a Mediterranean community of snakes in relation to prey availability. In: Revue d'Écologie (La Terre et La Vie), tome 50, n°4, 1995. pp. 353-363
Evaluating the island effect on phenotypic evolution in the Italian wall lizard, Podarcis siculus (Reptilia: Lacertidae)
No full textIslands are compelling natural laboratories for studying evolutionary processes. Nevertheless, the existence of general rules underlying morphological evolution on islands remains an unresolved issue. In this study, we investigated the insular phenotypic variability of the Italian wall lizard (Podarcis siculus) on a large geographical scale, in order to assess the putative existence of an island effect on three morphological head traits: shape, size and degree of sexual dimorphism. A geometric morphometric analysis was performed on 30 island and 24 mainland populations, involving a total of 992 specimens, and we analysed differences in both mean trait values and variances (disparity). We found increased shape disparity in insular lizards with respect to mainland ones. On the other hand, both size disparity and mean head dimensions of males decreased on islands, leading to a reduction in sexual dimorphism. Our results provide evidence for a multidirectional morphological diversification on islands concerning head shape of both sexes, while directional and canalizing selection likely occurred for head size, but only in males. Our findings improve our knowledge on the effect of insularity in Podarcis siculus, and highlight the need for an exstensive sampling scheme and a multi-trait methodological approach
Long-term, climate change-related shifts in monthly patterns of roadkilled Mediterranean snakes (Hierophis viridiflavus)
No full textEctothermic vertebrates depend on ambient temperatures for their activities. Thus, global warming is expected to influence several aspects of their ecology. Here, we use a >20 year (1990-2011) dataset on monthly numbers of roadkills in an area of central Italy in order to document whether the phenology of a Mediterranean population of Western whip snakes (Hierophis viridiflavus) has changed over time. Annual variation of roadkills was correlated to five climatic variables: (i) mean annual air temperature, (ii) mean February air temperature, (iii) mean July air temperature, (iv) yearly number of rainy days, and (v) number of rainstorm days. Increases in mean annual temperature were positively related to the number of roadkills at the early (February and March) and late (December) phases of above-ground activity, but were negatively related to the number of roadkills during summer (June and July). Intriguingly, we documented a shift in the annual mortality peak over the study period, possibly indicating temporal changes of the mating season due to global warming. Increasing mean air temperatures apparently caused an earlier onset of above-ground activity of snakes and delayed hibernation, but reduced the intensity of snake above-ground activity during the hottest and driest period of the year. Rainfall variables had no impact on snake activity
Il Database Erpetologico Laziale: da banca dati delll'Atlante ad aggiornato sistema informativo
No full textAn herpetological database on amphibians and reptiles occurring in the Latium Region was built up by a team of Roman herpetologists. After the publication of the Atlas, the team is carrying out an updating of the data base. The aim is to use the gathered information for ecological studies and conservation planning
Does interspecific competition with a stronger competitor explain the rarity of an endangered snake on a Mediterranean island?
No full textInterspecific competition has been demonstrated to be an important shaping force for snake communities worldwide, but relatively few studies have investigated its occurrence and extent with island assemblages of snakes. In Sardinia (Mediterranean Sea), two species of whip snakes (Colubridae) co-occur, one of them being abundant and widespread (Hierophis viridiflavus) and the other being localized and critically endangered (Hemorrhois hippocrepis). A previous hypothesis suggested that the latter species would be confined to suboptimal habitats by the former species, which is a stronger competitor for food. As a consequence, He. hippocrepis would not only be rare but would also be smaller in body size in Sardinia than in other regions of its range where Hi. viridiflavus does not occur. In 1999-2010, we studied habitat selection, food habits, and body sizes of these two snakes in sympatric populations, applying a suite of statistical tools including null models and Monte Carlo simulations. We observed that dietary habits were different between species (compared to Hi. viridiflavus, He. hippocrepis more frequently preyed upon rodents and less frequently on lizards, and within rodent prey, more frequently upon Rattus and less frequently upon Mus), but not in a way compatible with competitively induced trophic niche partitioning. The two species were similar in terms of prey size and predator-size-prey-size relationships. They also differed in habitat selection (maquis was the preferred habitat for both, but Hi. viridiflavus was found significantly more often than He. hippocrepis in grasslands, cultivations, and artificial pinewoods) but again in a non-competitively directed way. In addition, there was no evidence for the hypothesis that He. hippocrepis was confined to suboptimal habitats. Body sizes were similar between species (with males being significantly larger than females), and Sardinian He. hippocrepis were not smaller than conspecifics inhabiting regions without Hi. viridiflavus. Overall, our study showed that the two species differed in some aspects of their ecology, but these differences could not be due to competitive interactions. The conservation implications of these results are also discussed. © 2012 The Ecological Society of Japan
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