Biogeography

Biogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance. As writer David Quammen put it, "...biogeography does more than ask Which species? and Where. It also asks Why? and, what is sometimes more crucial, Why not?." 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 so on), and river capture, in combination with the area and isolation of landmasses (geographic constraints) and available energy supplies.