Abstract

Four subpopulations of Phyllotis darwini were monitored through monthly censuses conducted over 48 months on opposite slopes of two creeks separated by 2 km at a semiarid locality in Chile. Nine response variables were measured to characterize the spatial and temporal variability of the subpopulations: number of individuals per grid; mean body mass; coefficient of variation in body mass; coefficient of variation in body mass of males; coefficient of variation in body mass of females; number of males; number of females; number of juveniles; number of adults. These variables were analyzed with regard to two main factors (creek and slope). The demographic characteristics were more variable at a lower spatial scale (slope exposure) than at a larger spatial scale (creek). In situ reproduction and recruitment on each slope, as well as the low level of migration between slopes, indicate that this system is not driven by source-sink dynamics. The spatial and temporal dynamics of these subpopulations can be characterized as a partially coupled metapopulation system whose component subpopulations are weakly interconnected by dispersal between opposite slopes and totally unconnected between creeks.