Intraspecific variability may not compensate for increasing climatic volatility.
The role of intraspecific variability is being examined to improve predictions of responses to climate change or invasions and in research on diversity. Simultaneously, the probability and implications of increased high-frequency climate variability have been raised. An agent based model simulated two species on an environmental gradient representing an alpine treeline; a trend in its volatility was added. The species have different levels of variability, and each individual has further unique heterogeneity. Environmental volatility and individual heterogeneity were based on tree ring data from Pinus albicaulis. Simulations show that increasing volatility leads to population declines, including extinctions, and to sharper ecotones, and this impact is only slightly lessened by higher heterogeneity. Some simulation runs reveal an unanticipated selection for greater individual variability when volatility creates strong negative anomalies that fall short of extinction events. Increasing volatility can have significant ecological impacts because negative anomalies are not balanced by positive ones.