Print PageRapid evolution of ecologically important traits is now known to be widespread in natural populations, resulting from changes in the direction or strength of selection. However, very little is known about how important these rapid evolutionary changes are for ecosystem structure and function. In this talk we present a versatile approach to quantifying the importance of rapid evolution in the context of multiple factors determining an ecologically important variable. Previously we showed how this could be done when trait change is entirely caused by evolution (Hairston et al. 2005, Ecology Letters). But when substantial non-heritable trait change occurs, for example due to phenotypic plasticity or change in population structure, that approach can seriously over- or under-estimate the ecological impact of rapid evolution.
Results/Conclusions
By combining our previous approach with the Price Equation, we obtain a three-way partitioning of change in an ecological response variable into contributions from evolution, non-heritable phenotypic change and environmental change. Analyzing empirical examples involving fish, birds, and zooplankton, we find that the proportional contribution of rapid evolution varies widely, even among different variables responding to the same evolutionary change, and that rapid evolution can be important when it acts to oppose and mitigate phenotype effects of environmental change. These findings suggest that, paradoxically, rapid evolution may be most important when it is least visible, and a key to understanding how species and communities persist in the face of constant change in their biotic and abiotic environments.
