The importance of time scale in conservation biology and ecology

The issue of time scaling in conservation biology and ecology is rarely considered, yet has crucial implications. If time scale is inappropriate, it impedes the search for generalities. Data on threatened species are typically limited, so the search for generalities is important in conservation biology where extrapolations from well studied taxa to threatened species are often needed. When time scale is specified in conservation biology and ecology it is typically defined in years. However, theoretical and empirical evidence indicates that extinction risk scales to generations, as do catastrophes, and environmental and genetic stochasticity. Examples are given of important insights achieved by analyses using generations. Conversely, human social and political considerations are more likely to require scaling to years, so the purpose of studies needs to be carefully defined. Progress in conservation biology and ecology will be impeded if the issue of time scale is not addressed carefully.