Biogeography is the study of the distribution of species (biology), organisms, and ecosystems in geographic space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area.

Knowledge of spatial variation in the numbers and types of organisms is as vital to us today as it was to our early human ancestors, as we adapt to heterogeneous but geographically predictable environments. Biogeography is an integrative field of inquiry that unites concepts and information from ecology, evolutionary biology, geology, and physical geography.

Modern biogeographic research combines information and ideas from many fields, from the physiological and ecological constraints on organismal dispersal to geological and climatological phenomena operating at global spatial scales and evolutionary time frames.

The patterns of species distribution across geographical areas can usually be explained through a combination of historical factors such as: speciation; extinction; continental drift; glaciation, and associated variations in sea level, river routes, and habitat; and river capture; in combination with the geographic constraints of landmass areas and isolation; and the available ecosystem energy supplies.