Life history of a neotropical marsupial: Evaluating potential contributions of survival and reproduction to population growth rate

The relative effect of survival and reproductive rates to population growth rate is expected to be similar across species with similar life-histories. We employed a matrix population model and sensitivity and elasticity analysis to assess the absolute and relative importance of age-specific survival and fertility to population growth rate of Didelphis aurita (Didelphimorphia, Didelphidae) in a rural area of Rio de Janeiro, southeastern Brazil. The results were compared to expectations for mammals that mature early and have short generation time, such as D. aurita. Prospective analysis showed that changes in pouch young and juveniles survival would have large effects on population growth rate, relative to other vital rates, being the most critical time periods in the life cycle of D. aurita, whereas the effect of fertilities were always low. These findings do not fit to the observed pattern in mammals that mature early, where reproductive parameters have the largest relative influence on population growth rate. Although reproductive rates were characterized by a relatively small influence on population growth rate, they are still relevant because of their high variability and response to potential environmental disturbances. The first application of matrix population models to a neotropical rainforest marsupial provides information on marsupial demography and life-history strategy, increasing comprehension of this unknown group.