Ecological biogeography of North American mammals: species density and ecological structure in relation to environmental gradients

• Published in: Journal of Biogeography
• Main Authors: Badgley, Catherine E., Fox, David L.
• Other Authors: Museum of Palaeontology, University of Michigan, Ann Arbor, MI 48109, USA, Department of Earth Sciences, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Blackwell Science Ltd 2000
• Subjects: Biogeography; Climatic Gradients; Ecological Diversity; Ecological Structure; Mammals; North America; Geography and Maps; Social Sciences; Arctic
• Online Access: https://hdl.handle.net/2027.42/75250; https://doi.org/10.1046/j.1365-2699.2000.00498.x

Aim To evaluate the relationship of climate and physiography to species density and ecological diversity of North American mammals. Location North America, including Mexico and Central America. Methods Species density, size structure and trophic structure of mammalian faunas and nine environmental variables were documented for quadrats covering the entire continent. Spatial autocorrelation of species density and the environmental variables illustrated differences in their spatial structure at the continental scale. We used principal component analysis to reduce the dimensionality of the climatic variables, linear multiple regression to determine which environmental variables best predict species density for the continent and several regions of the continent, and canonical ordination to evaluate how well the environmental variables predict ecological structure of mammalian faunas over North America. Results In the best regression model, five environmental variables, representing seasonal extremes of temperature, annual energy and moisture, and elevation, predicted 88 of the variation in species density for the whole continent. Among different regions of North America, the environmental variables that predicted species density vary. Changes in the size and trophic structure of mammalian faunas accompany changes in species density. Redundancy analysis demonstrated that environmental variables representing winter temperature, frostfree period, potential and actual evapotranspiration, and elevation account for 77 of the variation in ecological structure. Main conclusions The latitudinal gradient in mammalian species density is strong, but most of it is explained by variation in the environmental variables. Each ecological category peaks in species richness under particular environmental conditions. The changes of greatest magnitude involve the smallest size categories (< 10 g, 11 100 g), aerial insectivores and frugivores. Species in these categories, mostly bats, increase along a gradient of decreasing winter ...