The term for the study of the distribution of species across space and time is biogeography. It examines where organisms live, where they lived in the past, and why their ranges have changed across landscapes and geological history.
Biogeography combines ideas from ecology, evolutionary biology, geology, paleontology, climatology, and physical geography. Researchers study patterns shaped by speciation, extinction, continental drift, glaciation, migration, habitat change, and geographic isolation. For example, isolated islands often contain species found nowhere else, while mountain ranges can separate populations and encourage divergence.
The field includes several branches. Phytogeography focuses on plants, zoogeography on animals, and mycogeography on fungi. Historical biogeography looks at long-term evolutionary patterns, whereas ecological biogeography examines how current environmental conditions influence distributions.
Biogeography is often confused with ecology. Ecology primarily studies interactions between organisms and their environments, usually at shorter timescales. Biogeography asks the broader geographic and historical questions: where is a species found, where did it originate, and what prevents it from living elsewhere?