On the Number of Habitats Embraced by the Geographical Ranges of Mammals in Texas

Abstract

Most species of land mammals in Texas have relatively small geographical ranges, as is also the case for North America. As geographical range size increases, the number of habitat types embraced by a range also increases.This relationship is nonlinear and is modeled by power law equations. The first derivative of these equations decreases with range size in Texas. This indicates that, in Texas, new habitat is embraced most rapidly by species with small ranges and, monotonically, less rapidly as range size increases. A power law also models qualitatively similar data for North America. In this case the first derivative increases with range size. On a continental scale new habitat is embraced least rapidly by species with small ranges and most rapidly by those with large ranges. State and continental patterns may differ from each other as a consequence of the spatial orientation and proportional size, relative to the study area, of geographical ranges and habitat.