Estratégia reprodutiva e organização espacial de uma população de Gracilinanus Agilis ( Didelphimorphia: Didelphidae) na Estação Ecológica do Panga, em Uberlândia/MG

Abstract

Attributes of the life history of organisms, such as reproductive strategy and use of space can directly influence population fluctuations, being fundamental to the understanding of the species ecology. In this sense, the present study aimed to characterize Gracilinanus agilis population and the spatial organization of males and females of the species in an area of Cerrado in Uberlândia / MG. Females of G. agilis presented synchronized and seasonal reproductive activity, and weaning was restricted to the rainy season, what may allow an increase in litter survival and body condition. Population dynamics data indicated a peak in population numbers during the reproductive period, followed by a sharp reduction in its size, which was possibly caused by post-mating mortality of adult males due to competition for females and the excessive energy expenditure. Adult females also presented a decrease in their numbers, but most adults females survived until January or February. Absolute male and female mortality result in non overlapping generations, characterizing semelparity. Regarding the use of the space of G. agilis, males presented larger home ranges than females, due to sexual size dimorphism and their reproductive patterns. On the other hand, arthropod biomass did not affect the home range of individuals. In the study, male s G. agilis did not exhibit territorial behavior, increasing home range overlap with females during the reproductive period in order to achieve more matings. In contrast, we observed that females occupied exclusive areas during the breeding season, suggesting territoriality among females. Accordingly, we suggest that the adoption of this strategy should occur during the reproductive activity, in order to defend exclusive access to food resources and protect litters from infanticide. Thus, we propose that the adoption of semelparity as a reproductive strategy may affect the maintenance of a territorial behavior, as well as territoriality should be favoured mainly in semelparous species. Accordingly, the exclusive access to resources is crucial for offspring survival and reproductive success of females that have a high reproductive investment in a single breeding season.