1,720,996 research outputs found
Estimating abundance of the Stripeless tree-frog Hyla meridionalis by means of replicated call counts.
No full textEuropean plethodontid salamanders on the forest floor: Local abundance is related to fine-scale environmental factors
No full textUnderstanding habitat selection by animal populations is one of the most relevant topics in ecology. In this study, we analyzed fine-scale habitat selection in a population of the salamander Speleomantes strinatii living in a Mediterranean forest environment. We used repeated surveys to estimate salamander abundance on 40 plots (12 m2) by applying hierarchical models to repeated count data. In addition, we estimated seven habitat variables for each plot to infer the relationships between local factors and salamander abundance. The salamander population showed a patchy distribution; higher abundances were found in plots with a prevalent North aspect and with a high number of rocks lying on the forest floor. Conversely, there was a negative influence of superficial water runoff on salamander abundance. Our results demonstrate that fine-scale environmental factors, mainly related to the physiological constraints of the salamanders, shape local abundance even in apparently suitable environments. Finally, the overall estimate of 0.86 individuals/m2 (95% CI 0.34-1.08) was similar to one obtained in a similar environment with removal sampling, suggesting efficiency of N-mixture modelling to estimate abundance of European plethodontids
Individual trophic specialisation in the Alpine newt increases with increasing resource diversity
No full textDietary studies suggest that amphibians are opportunistic predators. However, there is little information on the ability of individuals to change their feeding strategy in time because most studies do not evaluate prey availability and its effect on individual behaviour. To better understand how variation in prey availability may affect the feeding strategy of newts, we studied the Alpine newt, Ichthyosaura alpestris, during April and June in 2015, when we monitored prey availability and the species dietary habits. In April at low prey diversity, the newts were generalists, i.e., their diet overlapped almost completely with prey availability. In June when prey diversity was high, the newts became specialists. At the individual level, 9 out of 15 recaptured newts shifted from a generalist to a specialist feeding strategy from April to June, suggesting a rapid behavioural change in response to increasing prey diversity, in accordance with optimal foraging theory. These results stress the importance of sampling the same individuals several times during an extended period of time to better understand the patterns of diet variation in amphibians
Population size, age structure and life expectancy in a Lacerta agilis (Lacertidae) population from northwest Italian Alps
No full text
Data from: Potential rapid evolution of foot morphology in Italian plethodontid salamanders (Hydromantes strinatii) following the colonization of an artificial cave
No full textHow organisms respond to environmental change is a long-standing question in evolutionary biology. Species invading novel habitats provide an opportunity to examine contemporary evolution in action, and decipher the pace of evolutionary change over short time scales. Here we characterized phenotypic evolution in the Italian plethodontid salamander, Hydromantes strinatii following the recent colonization of an artificial cave by a forest floor population. When compared with a nearby and genetically related population in the natural forest floor and a nearby cave population, the artificial cave population displayed significant differences in overall foot shape, with more inter-digital webbing relative to the other populations. Further, this population evolved significantly larger feet, which corresponded more closely to those found in other cave populations than to forest floor populations to which the cave population is closely related. Finally, we quantified the rate of evolution for both foot shape and foot area, and found that both traits displayed large and significant evolutionary rates, at levels corresponding to other classic cases of rapid evolution in vertebrates. Together these findings reveal that the response to novel environmental pressures can be large and rapid, and that the anatomical shifts observed in the artificial cave population of H. strinatii may represent a case of rapid evolution in response to novel environmental pressures
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
