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Universidad de Buenos Aires (2014)

Los efectos de los cambios en las condiciones climáticas y ambientales sobre un ensamble de roedores sigmodontinos y la respuesta de sus principales depredadores en un área protegida de la ecorregión del Monte

Bisceglia, Silvina Beatriz Catalina

Titre : Los efectos de los cambios en las condiciones climáticas y ambientales sobre un ensamble de roedores sigmodontinos y la respuesta de sus principales depredadores en un área protegida de la ecorregión del Monte

The effects of changes in climatic and environmental conditions on assembly sigmodontine rodents and the response of its main predators in an area protected from the Monte ecoregion

Auteur : Bisceglia, Silvina Beatriz Catalina

Université de soutenance : Universidad de Buenos Aires

Grade : Doctor de la Universidad de Buenos Aires en el área de Ciencias Biológicas 2014

Résumé
The inter-specific interactions and environmental conditions (climate and vegetation) are considered the main factors in structuring the desert small mammal assemblages. In this work, the abundance and structure of small mammal assemblages of a protected area in the Monte ecoregion and its relationship with the cited factors were evaluated. The study was carried out in Lihue Calel National Park (La Pampa, Argentina) during four year (2008-2012). The main climate and vegetation parameters were described. The composition and abundance of the different species that characterize the small mammal assemblage were estimated and, simultaneously, the dietary compositions of the pampa gray fox (Pseudalopex gymnocercus) and the geoffroy´s cat (Leopardus geoffroyi) were studied. The results showed that the richness, abundance and diversity that characterize the mammal assemblage showed abrupt changes due to contrasting variation of the registred precipitation patterns occurred during the first two years (relatively drier) in comparison with the latter two (relatively wet). It was found that the variability in the abundance of rodent cricetids depended mainly on the continuity of rainfall and on the evapotranspiration intensity. However, the relationship between these climatic variables and population abundance was different for each species studied. The presence of different species of rodents, in every type of environment studied (shrublands, grasslands and forests), was mainly related to the cover of life forms found in the lower strata and, therefore, to the percentage of bare soil. Regarding predators, foxes and cats had different responses to the changes in the rodent abundance levels. The consumption by cats increased while the consumption by foxes remained constant when the abundance increased. Thus, it could be inferred that cats have a greater impact on rodent assemblage structure by presenting an immediate response to abundance changes. The results of this thesis showed the response of some of the components of the ecosystem to environmental changes that take place on Monte regions and their interpretation as a proxy for the degree of vulnerability and resilience of arids ecosystems. It is considered that the generated data are useful for the implementation of environmental management measures tending to keep the ecological stability in the protected area.

Mots clés : DESIERTO DEL MONTE ; VARIACIONES AMBIENTALES ; ROEDORES SIGMODONTINOS ; DEPREDADORES ; RESPUESTA DIETARIA ; MONTE DESERT ; ENVIRONMENTAL VARIABILITY ; SIGMODONTINE RODENTS ; PREDATORS ; DIETARY RESPONSE

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Page publiée le 25 janvier 2015, mise à jour le 3 juillet 2017