PARENT SESSION
Oral Session #14: Theoretical Ecology. Presiding: C. Klausmeier.
Monday, August 6, 2001. 1:00 PM to 4:30 PM. Hall of Ideas E.
Effects of local interactions on stability.
Neuhauser, Claudia1, 1
ABSTRACT- Mathematical models can help to resolve the longstanding question of whether more diverse communities are more stable. I will focus on how local dispersal and local interactions-hallmarks of spatial communities-affect stability. The results are based on a spatially implicit Markovian patch model with within patch population dynamics of the Lotka-Volterra type and between patch migration. I investigate the effects of species number, fecundity, and strength of competition on stability under limited dispersal (i.e., when not all offspring disperse). Whether local dispersal and local interactions increase or decrease stability depends on the type and strength of density dependent factors, such as fecundity and competition. Specifically, limited dispersal has a destabilizing effect on stability when fecundity is either low or when fecundity and competition are intermediate; limited dispersal has a stabilizing effect for high fecundity. The results are based on calculating analytical expressions on how the mean and the variance of abundance change with the migration parameter. A comparison with spatially explicit models will be made. This comparison will highlight the mechanism for the observed behavior in the spatially implicit model, namely spatial segregation of species within a patch when competition is relatively strong, which reduces the actual strength of competition.
KEY WORDS: stability-diversity hypothesis, competition, Markovian patch model