1,721,054 research outputs found
Trophic niche of cave populations of Speleomantes italicus
No full textThis paper investigates the trophic niche of a poorly studied cave salamander, Speleomantes italicus.
We examined Central Appennine hypogean populations that inhabit seven caves situated in three
limestone areas in Umbria Region (Italy). Adults displayed feeding activity from May to December
and the Vacuity Index analysis revealed a discontinuous trophic activity pattern throughout the year
related to prey phenology. According to the qualitative analysis of the trophic spectrum, the
populations in question can be defined as euryphagous, while the quantitative analysis (in terms of
number and volume of preyed taxa) revealed a specialist strategy with a clear preference towards
Diptera Limnobiidae. Both sexes presented similar trophic niche breadth and a high diet overlap,
showing no intersexual differences. The hypogean populations of S. italicus, similarly to S. strinatii,
showed a narrower trophic niche than epigeans of the same species, probably due to the limited food
availability in the cave habitat
Linking agricultural practices to lizard trophic behaviour: An ecological approach
No full text: Among intensive agricultural practices, pesticides, mowing, and heavy agricultural machineries have become an important tool to maximize harvesting and secure animal husbandry. However, they are also cause of agricultural ecosystem decline, often leading to degradation of key micro-habitat features for many species, higher predation risk and lower food availability. We investigated the diet and foraging ecology of the Italian wall lizard in agricultural areas to determine whether different management practices (conventional, organic, and control) can affect (i) the structure of the trophic niche of the species; (ii) prey diversity, the degree of individual specialization, and the overall population feeding strategy; (iii) lizards' health status. Faecal pellets were collected for diet composition analyses, while prey diversity in the environment was estimated by placing adhesive traps. Lizards' body condition did not differ among management type although males from control field resulted slightly larger than those from conventional and organic areas. The species showed a generalist (conventional and organic areas) and mixed (control area) feeding strategy with a preference for coleopterans. Although a different prey diversity was found in control areas compared to organic and conventional ones, diet composition and the importance of specific food items was similar among management types. This may suggest that management activities may have affected the overall prey availability and indirectly influenced lizard trophic behaviour. Our study provides a comprehensive knowledge on the feeding ecology of P. siculus in managed habitats, which may have useful implications for the overall conservation of lizards in agricultural environments
Alimentazione del gambero Austropotamobius italicus: osservazioni ecologiche ed implicazioni gestionali.
No full textFood selection strategy during the reproductive period in three syntopic hylid species from a subtropical wetland of north-east Argentina
No full textDendropsophus nanus, D. sanborni and Lysapsus limellum are three hylid species, similar in body size and frequently
coexisting at the same reproductive sites. To determine whether food partitioning occurred during the reproductive phase,
both numerical and volumetric analyses of stomach contents were performed on syntopic populations inhabiting a
wetland system in Corrientes Province, north-east Argentina. The analyses showed a marked specialization towards
Diptera prey in Dendropsophus species, particularly in D. sanborni, and a more generalist habit in L. limellum. The three
study species exhibited different foraging modes, with L. limellum belonging to the sit-and-wait predator type, D.
sanborni to the forager predator type, and D. nanus exhibiting a mixed foraging mode. The comparison of the feeding
strategies adopted by the various species in different habitat types and condition of syntopy showed a noteworthy
plasticity. According to Schoener’s food size selection strategy model for a syntopic predator species system, the larger
species (L. limellum) selected prey bigger in size and the smaller (D. sanborni) ate a larger number of prey specimens,
whereas D. nanus showed an intermediate trophic strategy. Although the degree of trophic niche overlap was higher
than expected, the study species did not show a clear segregation in terms of use of space, hence the coexistence mechanism
during the reproductive period should not be related to competition processes for food resources
Segregation structure in Odonata assemblages follows the latitudinal gradient
No full textLatitude is known to deeply affect life with effects generalizable into ecological rules; the increasing species diversity toward tropics is the most paradigmatic. Several hypotheses tested patterns of biotic interactions’ intensity along latitude. Negative interactions (i.e. competition and predation) are expected to be among the processes that produce checkerboard distribution of species. However, no relationship between checkerboardness and latitude has been uncovered. We tested Odonata assemblages worldwide for segregation patterns using a faunistic dataset (395 species arranged in 386 natural communities) spanning a wide latitudinal range (87°). We used co-occurrence analyses (C-score index and Standardized Effect Size) as an estimate of checkerboardness then correlated the occurrence of segregation to latitude. Odonata followed the Latitudinal Diversity Gradient at the regional scale (i.e. country scale) within our analyzed assemblages spanning, whereas local richness (i.e. community scale) did not follow the same pattern. Odonata assemblages structured with segregation are more common going from high to low latitudes, and local species richness have no effect on the pattern. We summarized hypotheses on how biotic interactions or ecological and historical processes can influence the spatial patterns in the checkerboards of assemblages and presented promising ways to help to gain a better mechanistic understanding of the drivers of the Latitudinal Diversity Gradient
Spatio-temporal resource use at a microhabitat scale in an amphibian community at a pond in Mediterranean Central Italy
No full textThe micro-habitat use in relation to the spatial and temporal context was studied
in a six-species-community of amphibians in a Mediterranean pond in Central Italy. Several
concurrent sets of statistical analyses, including univariate, multivariate and null model simulations,
were used in order to interpret the community structure. In terms of micro-habitat selection,
the newt species Tr i t u rus carnifex and T. vulgaris used primarily the aquatic habitats for most of the time spent in the pond, whereas the anuran species (Bufo bufo, Hyla intermedia,
Rana dalmatina and the green frogs) used mainly the terrestrial micro-habitats adjacent to the
pond except during the reproductive period when they used also the aquatic micro-habitats. A PCA analysis classifying the amphibian species on the basis of their spatio-temporal habitat use
put each species in a separate part of the multidimensional space, whereas another set of PCA
analysis revealed that, on the basis of the use of the aquatic micro-habitats, there were four
‘groups’: a) Hyla intermedia and the green frogs; b) Bufo bufo and Rana dalmatina; c) Tr i t u ru s
vulgaris; d) Triturus carnifex. Some species used the micro-habitats types in relation to their relative
availability in the field, whereas other were clearly selective in their requirements. Null
model analyses based on Monte Carlo permutations of overlap values (RA2 and RA3 algorithms)showed that the various species were arranged in the micro-habitat scale in a non-random way. The general implications of these results are discussed
“Heaven” of Data Deficient Species: The Conservation Status of the Endemic Amphibian Fauna of Vietnam
Full text linkPredicting the true status of Data Deficient (DD) species is a prominent theme in recent conservation biology, but there still is much debate regarding the conservation approach that should be used for DD taxa and no definitive conclusions are yet available. We review and analyse the current data available on the conservation status of amphibians in Vietnam, with an emphasis on the DD species. We also compare Vietnamese DD frequency of occurrence with other regions of the world, examine the extent of the range of taxa divided by Red List status, and explore the protection attributes of the taxa based on their inclusion within protected areas of Vietnam. We documented that the analysis of amphibians in Southeast Asia, and especially in Vietnam, substantially agrees with patterns highlighted by previous global research, and confirms the risk that several DD species may silently go extinct without their actual risk ever being recognized. Importantly, our study showed that fine-scale analyses are essential to highlight the potential drivers of extinction risk for the DD species of amphibians. A crucial next step for conservation policies in Vietnam (and in surrounding countries) is developing and implementing species-specific studies targeted at addressing each species’ drivers of extinction and determining science-based strategies for minimizing their extinction risk
Seasonal patterns of activity and community structure in an amphibian assemblage at a pond network with variable hydrology
No full textWe studied community structure and seasonal activity patterns in a system of four ponds
with seasonally-variable hydrology at a Mediterranean area in central Italy. We used a set
of field methods to assess species presence and relative frequency of observation. The
network of ponds was inhabited by six species of amphibians, two salamanders and four
frogs. The breeding phenology of the six species did not vary remarkably among ponds,
but there were significant differences among species in use of ponds. Factorial analysis
of pond similarity drawn from percentage composition of the amphibian fauna, revealed
that each of the four ponds was treatable as independent units, with no influence of relative
inter-pond distance. PCA analysis allowed us to spatially arrange the amphibian species
into three main groups: two were monospecific groups (i.e., Triturus vulgaris and Bufo
bufo) and the third consisted of those species that selected not only the largest-deepest
ponds, but also the ephemeral ones (i.e., Triturus carnifex, Hyla intermedia, the green frogs and Rana dalmatina). Our results suggest that the inter-pond differences in riparian vegetation,
water depth, aquatic vegetation structure/abundance, and soil composition may
produce differences among pond ecological characteristics (i.e., water turbidity and temperature,
shelter availability, abundance of oviposition micro-sites), which may in turn influence
different patterns of use by amphibians. To our knowledge, this is the first study
emphasizing the potential role of heterochrony in the maintenance of a high species richness in Mediterranean amphibian communities. Preservation of freshwater vertebrate
biodiversity requires management and protection not only of the main ponds and water bodies but also the temporary and ephemeral shallow ponds
Breeding birds in an Apennine massif (Majella, Central Italy: do "common species" could act as susrrogate for characterize species richness and composition of the communities?
No full textBreeding bird communities were studied in eight habitat types in the Majella massif (central Italy) in
two years (2007 and 2008) with two sampling methods (general survey and random point counts).
At level of the general survey, our data confirm as bird communities are structured in response to
vegetation structure and internal heterogeneity induced either by human activities (e.g., landscape patchiness) or natural limiting factors (e.g., linked to altitude). Richer habitat types correspond to
mosaics of oak woods in both of years. In this habitat, the high level of habitat heterogeneity could
increase the species richness at landscape level (i.e., γ-diversity). The low values in species richness observed in Pinus mugo formations and in primary pastures may be due to the altitudinal gradient
of species richness (inverse correlation between altitudinal mid-point of each habitat type and
number of species). Cluster analysis showed a first level of dissimilarity among faunal communities linked to the vegetation structure (forest versus open/shrubby habitat types), and a second one for
open/shrubby habitats could be based either on spatial-heterogeneity and altitudinal effect. At level
of species richness, a large proportion of the species (> 80%) has been sampled with random point count method when compared to general survey. Therefore, at species richness level, the method
with lower research effort could furnish a reasonable description of the communities. At species
composition level, data obtained by random sampling point count method showed different pattern
between years for several habitat typology, turning out less exhaustive than general survey
method. Therefore, in those habitat types a low research effort could expose the data to stochastic oscillations
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