Population dynamics of two rodent species in agro-ecosystems of central Argentina: intra-specific competition, land-use, and climate effects

VERÓNICA ANDREO; MAURICIOP LIMA; CECILIA PROVENSAL; JOSÉ PRIOTTO; JAIME POLOP

Population Ecology

Springer

Año: 2009 vol. 51 p. 1 - 6

1438-3896

Understanding the role of feedback structure(endogenous processes) and exogenous (climatic andenvironmental) factors in shaping the dynamics of naturalpopulations is a central challenge within the field of populationecology. We attempted to explain the numericalfluctuations of two sympatric rodent species in agro-ecosystemsof central Argentina using Royama’s theoreticalframework for analyzing the dynamics of populationsinfluenced by exogenous climatic forces. We found thatboth rodent species show a first-order negative feedbackstructure, suggesting that these populations are regulatedby intra-specific competition (limited by food, space, orenemy-free space). In Akodon azarae endogenous structureseems to be very strongly influenced by human land-userepresented by annual minimum normalized differencevegetation index (NDVI), with spring and summerrainfall having little influence upon carrying capacity.Calomys venustus’ population dynamics, on the otherhand, seem to be more affected by local climate, also withspring and summer rainfall influencing the carryingcapacity of the environment, but combined with springmean temperature.