Amphibian population declines: Evolutionary considerations

Numerous factors, such as global environmental changes, habitat destruction, introduced species, diseases, and chemical pollution, appear to be contributing to amphibian population declines. Moreover, the life history characteristics and behavior of many amphibian species appear to be placing them in jeopardy. Such behaviors and ecological attributes were molded over evolutionary time under selection pressures that acted on amphibians in a variety of ways. Many biologists who study amphibian population declines, however, have failed to consider some of these evolutionary aspects. Better understanding of amphibian population declines requires that scientists and policy makers consider the ecological processes associated with the declines in light of evolutionary principles such as these: Evolution is limited by historical constraints; not all evolution is adaptive; adaptations are often compromises; evolution can only alter existing variations; and evolution takes time.