Background/Question/Methods It is now widely recognized that substantial evolutionary change can occur on contemporary (or “ecological”) time scales. The outstanding question at present is the extent to which this evolution also shapes ecological dynamics at the population, community, and ecosystem levels.

Results/Conclusions At the population level, genetic factors have been shown to influence the dynamics of wild sheep, butterflies, and guppies. At the community level, differences among plant genotypes drive differences in arthropod communities, and phenotypic differences among fish populations shape prey communities. At the ecosystem level, genetic variation in plants and fish influence rates of nutrient cycling. Thus, evolution is an important driver of ecological dynamics in some systems and under some circumstances. A key research goal should be to define more generally the circumstances under which such effects are or are not important.