1,721,078 research outputs found
IX Italian congress of Mammalogy
No full textThe effects of recent climate change on mammals are increasingly well documented, and a large number of methods have been developed to predict the potential impacts of further climate change in the coming decades. A variety of studies have demonstrated that species displaying certain ecological and life history traits (e.g. low dispersal, large body mass, low reproductive rates) are more vulnerable to extinction based to climate change than others. Despite these efforts, little is known about how to represent species vulnerability to climate change due to biological traits. Here we present a framework for assessing three components of vulnerability: exposure, sensitivity and adaptability. We developed two indices for each Italian terrestrial non-volant mammal (64 species) by considering a) life history traits which make a species more sensitive and less adaptable to climate change, and b) the areas with the greatest exposure (differences between current and projected future climate) b
Projected Global Loss of Mammal Habitat Due to Land-Use and Climate Change
Get PDFHuman pressure on the environment is driving a global decline of biodiversity. Anticipating whether this trend can be reverted under future scenarios is key to supporting policy decisions. We used the InSiGHTS framework to model the impacts of land-use and climate change on future habitat availability for 2,827 terrestrial mammals at 15 arcmin resolution under five contrasting global scenarios based on combinations of representative concentration pathways and shared socio-economic pathways between 2015 and 2050. Mammal habitat declined globally by 5%–16% depending on the scenario. Africa (with declines up to 25%) and South America were the most affected regions. African insectivores, primates, Australian carnivorous marsupials and marsupial moles, and South American opossums declined the most. Tackling this loss would require a mix of actions across scales, including a global shift toward sustainability, addressing land-use change in sub-Saharan Africa, and helping endemic species track climate change in South America
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Fire policy optimization in Kruger National Park to maximize suitable habitat for rare antelopes
No full text1. Fire is a key ecosystem driver in savannas and it can have large impacts on species’ distribution and density. A re-examination of fire management in Kruger National Park is currently under review with the objective to maintain natural ecosystem dynamics and favour tourists’ ability to observe animals.
2. We used data on location, intensity and frequency of fires and census data on tsessebe, roan antelope, sable, eland and nyala to estimate the relationship between fire occurrence and species’ occurrence and density. We also investigated the impacts of different environmental predictors on antelope populations. We identified the spatial trade-off between the conservation of species attracted by burnt areas (e.g. sable) and species that avoided them (e.g. eland).
3. The model predictors that affected the most the density and presence of antelopes were mean fire return period, zebra and wildebeest density and the presence of waterpoints.
4. We used our models to evaluate different f
Ecological correlates of dispersal distance in terrestrial mammals
No full textDispersal distance in mammals is a fundamental information for several ecological and conservation applications. Although dispersal can depend on many intrinsic and extrinsic factors, in recent years many studies have shown that it scales with body size and home range area. However, the role of further ecological correlates to distance travelled is still unclear and the predictive models proposed so far have suffered from small sample size and lack of error estimates. This reduces the practical relevance of the models for ecological and conservation applications. We conducted a comprehensive meta-analysis on 327 studies on the dispersal of 164 mammal species, and performed linear and non-linear regression analyses to explore the relationships of body size and home range area with dispersal distance. We tested the effect of various life history traits and ecological factors on the relationships and performed a sensitivity analysis to evaluate the robustness of the models to sample size. The linear relationships of both home range and body size with dispersal distance were influenced by various life history traits and ecological factors. We developed allometric functions to estimate species dispersal distance based on different predictors and life history traits. Linear models representing the relationship between dispersal distance and body size or home range area received good support; however logistic models better approximates both relationships. Despite receiving less support than a logistic curve, a linear model between dispersal and home range is a good approximation for applicative purposes. Sensitivity analysis showed that our results are robust to subsampling of the original dataset until a sample of 40 species. Our empirical models have the potential to improve theoretical and applied population biology studies by extending the applicability and improving the accuracy of dispersal distance estimation to a large number of mammals
Fire policy optimization to maximize suitable habitat for locally rare species under different climatic conditions. A case study of antelopes in the Kruger National Park.
No full textFire is a key ecosystem driver in savannahs and it can have large impacts on species distribution and density. A reexamination of fire management in Kruger National Park is currently under review with the objective to maintain natural ecosystem dynamics and favour tourists' ability to observe animals. We used data on location, intensity and frequency of fires and census data on three species considered as rare and of conservation concern in the park, tsessebe, roan and sable antelope to estimate the relationship between fire occurrence and species occurrence and density. We also investigated the impacts of different environmental predictors on antelope populations. The model predictors that most affected the density and presence of antelopes were mean fire return period, the type of geological substrate and the presence of water-points. We then used our models to evaluate different fire management scenarios and make recommendations for an optimal fire management strategy for the conservation of these rare antelopes. We also tested our scenarios under different precipitation conditions, in order to investigate the likely response of species to climate change. Roan antelope is the most sensitive species to climatic variations, while sable seems to be the most resilient. The approach described here can also be used to improve the conservation of locally rare species in other regions and habitats
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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