zoogeography

Zoogeography is the branch of biogeography that studies the geographic distribution of animal species across space and through time. It seeks to understand why particular assemblages of animals occur in some regions and not others, and how historical and ecological processes shape these patterns. Core questions include the origins of regional faunas, mechanisms of dispersal and vicariance, barriers to gene flow, and the role of climate, geology, and ecological interactions in producing present-day distributions. Methods combine mapping of species ranges, palaeontological data, comparative anatomy and phylogenetics, and modern tools such as molecular phylogeography and ecological niche modeling.

Historical development: early naturalists observed regional faunas; Alfred Russel Wallace and other 19th-century scientists popularized the concept of biogeographic realms. The classic framework identifies major realms or regions (for example Nearctic, Palearctic, Afrotropic, Indomalayan, Australasian, Neotropical), with some schemes adding Oceanian and Antarctic realms.

Key patterns include endemism, particularly on islands and in isolated continents, and latitudinal diversity gradients with higher richness in the tropics. The processes of vicariance (archipelagos, continental breakups) and long-distance dispersal, along with extinction, climate shifts, and plate tectonics, shape these patterns. Island biogeography theory links island size and isolation to species richness.

Applications include conservation planning, biogeography-based region delineation, and forecasting responses to climate change, invasive species, and habitat loss.

Case studies highlight the distribution of African cichlids, Madagascar’s lemurs, and marsupials in Australia, illustrating how geography constrains evolution and diversification.