Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics.
Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants' dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution - a signal of spatial self organization - but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America.
Doug
D
Jackson
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America; School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, United States of America.
John
J
Vandermeer
School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, United States of America.
Ivette
I
Perfecto
Environmental Studies Department, University of California Santa Cruz, Santa Cruz, California, United States of America.
Stacy M
SM
Philpott
D063147:Animal Distribution; D000818:Animals; D001000:Ants / Q000502:physiology*; D003198:Computer Simulation; D004777:Environment; D008800:Mexico; D008954:Models, Biological; D009425:Nesting Behavior / Q000502:physiology*; D011157:Population Dynamics; D013037:Spatial Behavior / Q000502:physiology*; D014197:Trees; D014329:Tropical Climate