Niche overlap and environmental variability

Abstract

This article investigates whether several forms of environmental variability will limit niche overlap in a group of competing organisms. A simulation method was used to answer this question for the Lotka-Volterra model of competition. The basic result is that the maximum tolerable variability is significantly less for systems with high overlap when the fluctuations in the per capita rates of increase are uncorrelated or negatively correlated. However, in most natural situations fluctuations are more likely to be positively correlated, and in this case systems with high overlap may often tolerate as high levels of variability as systems with low overlap. Thus it seems unlikely that lower species diversity in fluctuating environments is due to a lower maximum tolerable niche overlap. The present results are compared with approximate analytical results obtained by May [7].