Revista Chilena de Historia Natural 79 (3): 295-308, 2006
RESEARCH ARTICLE
Adult survival and population dynamics in the leaf-eared mouse
Phyllotis darwini in central Chile
Classic results of matrix models predict that, in species with a long
generation time, adult survival should be the demographic parameter driving population dynamics whereas, in species with a short
generation time, adult survival should not be of such importance. Nonetheless, Yoccoz et al. (1998, Research Population Ecology 40:
107-121) hypothetized that, in small rodents, adult survival should be the demographic parameter driving the population growth rate if
one considered a time scale of one month (instead of one year). As far as we know, this hypothesis has not yet been tested with
empirical data. To test this hypothesis, we used five years of capture-mark-recapture data to estimate maturation and survival of a
rodent, the leaf-eared mice, Phyllotis darwini, in a population of central Chile. This analysis revealed that the probabilities of
survival decreased with the average rainfall by year and that the probabilities of maturation decreased with the abundance of the
population. Using the probabilities of survival and maturation, we built up a seasonal matrix model and use perturbation analysis
(elasticity) to be able to actually measure the relative importance of each demographic parameter to the population growth rate.
Environmental seasonality was incorporated in the model by using a rainfall season, of five months long, and a dry season. Adult
survival was indeed the demographic parameter with the highest elasticity. Such a result plainly supported thus the hypothesis of
Yoccoz et al. (1998).
Key words:
maturation,
survival, matrix model, capture-mark-recapture, Phyllotis
