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Universidade de Brasília (2011)

Dinâmica populacional de roedores de um cerrado do Brasil Central

Rocha, Clarisse Rezende

Titre : Dinâmica populacional de roedores de um cerrado do Brasil Central

Auteur : Rocha, Clarisse Rezende

Université de soutenance : Universidade de Brasília

Grade : Doutorado em Ecologia (2011)

Résumé
The structure of a population is determined by factors such as density, distribution of individuals in the habitat, proportions of individuals in different age groups, sex ratio, home range and behavior. This study intended to characterize the factors and their determinants affecting the variation of three cricetid rodent population density in the Brazilian cerrado. This study was conducted in two grassland areas at the Estação Ecológica de Águas Emendadas in the Distrito Federal, Brazil, from 2004 to 2009. Fifty Sherman traps were monthly baited during six consecutive nights at each grid.The size of rodents’ home range differed between sexes, but it was not related to reproduction, seasons or body masses. The abundance of Thalpomys lasiotis influenced the home range size of that species. However, abundance influenced overlapping for the three species individual. Male overlapping was higher than females’. The environmental variables explained 21% of the community composition. The variation in grasses density and in the number of “termite mounds” and “murundus” were the variables that most influenced the rodents’ populations. Necromys lasiurus occurred in places with higher density of grasses, while T. lasiotis and Calomys tener occurred in environments with lower density of grasses. The dry season was the period of increased recruitment of juveniles of C. tener and T. lasiotis. Necromys lasiurus juveniles were found throughout the year. Their lower body mass in the dry season was attributed to biological factors such as age of individuals and environmental factors such as the lower supply of resources during the season. In general, the grassland rodents, showed seasonal reproduction, with higher peaks in the rainy season.Calomys tener and T. lasiotis showed distinct seasonal variation in population size between the dry and rain seasons. The abundance annual variation was also important for two of the three species. Necromys lasiurus showed population fluctuations, on average, every two years and T. lasiurus presented a decline in population densities over the six years of the study

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Page publiée le 8 février 2015, mise à jour le 7 juillet 2017