Centro di Studi Ambientali Demetra Srl

Rome, Italy

Centro di Studi Ambientali Demetra Srl

Rome, Italy
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Walker R.,Nautilus Ecology | Walker R.,Open University Milton Keynes | Luiselli L.,Centro di Studi Ambientali Demetra S.r.l. | Rafeliarisoa T.,University of Antananarivo | Rafeliarisoa T.,Grewcocks Center for Conservation and Research
Amphibia Reptilia | Year: 2012

The spider tortoise (Pyxis arachnoides) is endemic to the coastal, dry forests of southwest Madagascar, one of the country's most threatened habitats. Very little is known of the biology of this Critically Endangered species. We devised a three year capture-mark-recapture study to assess mean annual survival for the following cohorts; juvenile, adult male, adult female and adult of both sexes, for a population of spider tortoises using a Cormack-Jolly-Seber model. Low recapture probabilities prevented the modelling of all but the adult of both sexes cohort. Mean annual survival was 0.823 (SE = 0.15; 95% CI = 0.565-1.0). We hypothesise that habitat loss could be impacting the survival of this cohort; however establishing control data to test for this is difficult because of the widespread habitat loss, even within protected areas. Therefore we suggest extending the study across a number of gradients of impacted habitat and increase the duration of the study to assess this risk to the population and improve model robustness. © 2012 Koninklijke Brill NV, Leiden.

Mebert K.,University of Basel | Jagar T.,Herpetolosko drustvo Societas herpetologica slovenica | Grzelj R.,Herpetolosko drustvo Societas herpetologica slovenica | Cafuta V.,Herpetolosko drustvo Societas herpetologica slovenica | And 7 more authors.
Biological Journal of the Linnean Society | Year: 2015

Contact zones of closely related and ecologically similar species constitute rare opportunities to study the evolutionary consequences of past speciation processes. They represent natural laboratories in which strong competition could lead to the exclusion of one species, or the various species may switch into distinct ecological niches. Alternatively, if reproductive isolation has not yet been achieved, they may hybridize. We elucidate the degree of taxon integrity by comparing genetics and habitat use of three similar-sized congeneric viper species, Vipera ammodytes, Vipera aspis, and Vipera berus, of Nadiza Valley in western Slovenia. No hybridization was detected for either mitochondrial or nuclear genomes. Similarly, external intermediacy by a single prestudy viper (probably V. ammodytes × V. aspis) indicates that hybridization occasionally occurs, but should be very rare. Populations of the three related viperids are partially allopatric in Nadiza Valley, but they also coexist in a narrow contact zone in the montane grassland along the south-exposed slope of Mount Stol (1673 m a.s.l.). Here, the three species that occupy areas in or near patches of rocky microhabitats (e.g. stone piles, slides, and walls) live in syntopy. However, fine-scale measurements of structural components show partial habitat segregation, in which V. berus becomes more dominant at elevations above 1400 m and occupies mostly the mountain ridge and north-exposed slopes of Mount Stol, V. aspis occurs below 1300 m and is the only species to inhabit stoneless patches of grass and bushes around 1000 m and lower, and V. ammodytes occurs at all elevations up to 1500 m, but is restricted to a rocky microhabitat. We suggest that a high degree of microstructure divergence, slightly different environmental niches, and a generally favourable habitat for all three viper species, keep the pressure for mis-mating and hybridization low, although mechanisms such as reduced hybrid inferiority and temporal mating segregation cannot yet be excluded. © 2015 The Linnean Society of London.

Kolbe J.J.,University of Rhode Island | Lavin B.R.,University of California at Berkeley | Lavin B.R.,Sonoma State University | Burke R.L.,Hofstra University | And 3 more authors.
Biological Invasions | Year: 2013

Tests of invasion success often require comparisons between introduced and native populations, but determining the native-range sources for introduced populations can be difficult. Molecular markers can help clarify the geographic extent of native-range sources, helping to identify which populations are appropriate for comparative studies. The Italian Wall Lizard (Podarcis siculus) was introduced multiple times to the United States with extant populations in California, Kansas, New Jersey, and New York. We used phylogeographic analysis of mtDNA sequences (cytb gene) for individuals sampled from these introduced populations and across the native range to identify the number of independent introductions and the location of the source populations. Haplotypes sampled from introduced populations were nested within three geographically distinct, well-supported clades that together encompassed a large portion of the native range. Combining these phylogeographic results with documentation of the introductions revealed putative sources: California individuals are derived from Sicily; Kansas and New York populations are from Tuscany near Florence; and the New Jersey population is likely from the Adriatic coastal region, but a more specific locality is not possible. The pet trade dominates the invasion pathway for P. siculus introductions to the US. The genetically and geographically diverse sampling of its native range may be driven by the desire for phenotypic variety in the pet trade, a hypothesis that needs future testing. © 2012 Springer Science+Business Media B.V.

Battisti C.,Environmental Service Inc. | Luiselli L.,Centro di Studi Ambientali Demetra s.r.l.
Journal for Nature Conservation | Year: 2011

In connectivity conservation and ecological network planning, the selection of focal fragmentation-sensitive species represents a priority step. Nevertheless, despite their strategic role, selection of focal species has traditionally been carried out using charismatic and/or non objective approaches. In this way, actions of planning and conservation could be ineffective. Using as a case study Italian reptiles, we apply an expert-based approach for the selection of focal species on the basis of sensitivity to components of habitat fragmentation (habitat area reduction, increase of habitat isolation, increase of edge effect and landscape matrix disturbance) and of intrinsic ecological traits of the species (trophic level, dispersal ability, body size, niche breadth, rarity). The threshold values for each component of fragmentation defined a set of 21 focal species that can be divided into the three macro-components of human-induced habitat fragmentation (HIHF) towards which they show a sensitivity, the suitable spatial scale of populations and relative suitable habitat categories. Among these species, seven can be sampled easily with standard, low-cost field protocols. The selected species largely coincide with the species known in literature as fragmentation-sensitive. © 2010 Elsevier GmbH.

Del Vecchio S.,Third University of Rome | Burke R.L.,Hofstra University | Rugiero L.,Centro di Studi Ambientali Demetra s.r.l. | Capula M.,Museo Civico di Zoologia | Luiselli L.,Centro di Studi Ambientali Demetra s.r.l.
Herpetologica | Year: 2011

Herbivory is the dominant feeding strategy in tortoises, and dietary shifts are common in response to changes in resource availability. We conducted the first large-scale study of the diets of wild Hermann's Tortoises (Testudo hermanni hermanni) and found that the study population in central Italy was strictly herbivorous. The tortoises ate primarily legume leaves and grasses in the spring, and switched to flowers and unripe fruit of Ruscus aculeatus as these became available in the autumn. There were no significant differences between the diets of males and females. Although tortoise diets included both rare and abundant plant species, they consumed abundant plant species in a higher proportion than those species occurred in the study area. However, some rare plants made up relatively large fractions of the diet, and one of the few nonnative plants (Conyza canadensis) at the study area was eaten frequently by tortoises in all seasons, despite its relative rarity. Ruscus aculeatus berries may be particularly valuable to tortoises that are about to enter hibernation; hence, T. hermanni habitat should be managed to maintain this important plant species. © 2011 by The Herpetologists' League, Inc.

Luiselli L.,Centro di Studi Ambientali Demetra s.r.l. | Rugiero L.,Centro di Studi Ambientali Demetra s.r.l. | Massimo C.,Museo Civico di Zoologia
Herpetological Journal | Year: 2011

Snakes are rather difficult subjects for demographic studies. When snakes are not abundant in the feild, herpetologists have learnt that a good method for population studies is to rely on mass captures at den sites. In several snake species females also exhibit oviposition at communal nest sites, which are utilized year after year. These oviposition sites may then serve to record individuals for snake population studies. Here, we compared population size estimates generated from a 17-year study of gravid females at a communal nesting site (CNF) with population size estimates from the same snake population across an 8-year traditional capture-mark-recapture (CMR) study. Although in our case only open population methods are appropriate for calculating yearly population sizes, we also used closed population methods in order to highlight an eventual effect of the models used. As a study species, we used the European whip snake (Hierophis viridifavus) at a site in Mediterranean central Italy. Overall, population size estimates were significantly different between the two methods, with estimates from the CNF samples always higher than those obtained with traditional CMR. This difference was particularly strong with closed population methods, but still evident with open population models when the whole study period was considered. However, there were no statistical differences between population sizes estimated with CNF and CMR when only a subset of years (2002-2009) was used. No statistical relationship between population size estimates with CMR against CNF by year was uncovered, showing that CNF samples did not capture inter-annual variations in population sizes. We conclude that it might not be sound to use population size estimates from CNF samples instead of more traditional CMR studies, although yearly population size variations may at least in part be responsible for the differences between CNF and CMR estimates.

Filippi E.,Centro di Studi Ambientali Demetra Srl | Rugiero L.,Centro di Studi Ambientali Demetra Srl | Capula M.,Museo Civico di Zoologia | Burke R.L.,Hofstra University | Luiselli L.,Centro di Studi Ambientali Demetra Srl
Chelonian Conservation and Biology | Year: 2010

Herman's tortoise, Testudo h. hermanni, is an endangered subspecies in Italy, France, and Spain. We studied a Herman's tortoise population in the Riserva Naturale Regionale Monterano in the Tolfa Mountains of central Italy. We found that, unlike most other studies of this and related species, sex ratios were 11, and half the population was made up of juveniles. Sexual maturity was reached at 12 years in males and 1213 years in females, and females were significantly larger. Tortoises greatly preferred open maquis habitat over other habitat types and thermoregulated so that body temperatures stayed consistently above ambient temperatures, especially under low ambient temperature conditions. Presence of ticks was significantly associated with an index of thermoregulatory behavior. We suggest that maintenance of open maquis habitat in this reserve is essential to high hatchling production and effective thermoregulation. © 2010 Chelonian Research Foundation.

Rulison E.L.,Hofstra University | Luiselli L.,Centro di Studi Ambientali Demetra S.r.l. | Burke R.L.,Hofstra University
American Midland Naturalist | Year: 2012

We compared relative impacts of habitat type vs. location in the diet of a generalist omnivore, the raccoon (Procyon lotor). Raccoon diets were analyzed from 161 scat samples collected in a marine coastal habitat over 13 mo. We used a suite of statistical tools including univariate indices of diversity, descriptive statistics, niche similarity analyses, and two contrasted randomization algorithms with Monte Carlo to test whether raccoons maintained similar diets in different habitats. We compared these results to raccoon diet studies in geographically distant locations with similar habitats to relevant studies conducted geographically closer but with different habitats. Logistic regression analyses revealed that among habitat similarity, geographic closeness, and diet diversity (i.e., relative dietary specialization of each population), only habitat similarity significantly (and positively) influenced probability of observing a greater-than-expected diet similarity. This demonstrated that raccoons in similar habitats had similar diets, with substitution of ecologically equivalent prey species.

Vecchio S.D.,Third University of Rome | Burke R.L.,Hofstra University | Rugiero L.,Centro di Studi Ambientali Demetra S.r.l. | Capula M.,Museo Civico di Zoologia | Luiselli L.,Centro di Studi Ambientali Demetra S.r.l.
Animal Biology | Year: 2011

Although research on habitat use and habitat selection is essential for understanding population ecology and behavior, most such zoological studies have used only general habitat categories describing main habitat features instead of using modern plant ecological approaches. Here, we analyze Testudo hermanni microhabitat use at a coastal Mediterranean site in central Italy by modeling tortoise presence/absence at three spatial scales, using a logistic regression design and quantitative vegetation and plant community analysis to reveal correlates of tortoise habitat use on a fine scale. Our analyses showed that only a few plant species among the many present, and these on a very small spatial scale, are important determinants of tortoise presence and site selection. We also find that tortoises chose a paradoxical combination of high levels of bare soil and high total vegetation cover. This suggests that these tortoises are selecting small patches of habitat in a matrix of less desirable habitat. Our findings also have important implications for habitat management, in that increasing the number of habitat patches containing the few significant plants is likely to be desirable, whereas increasing the size of such patches is probably less relevant. © 2011 Koninklijke Brill NV, Leiden.

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