An ecozone or biogeographic realm is the largest scale biogeogrpahic (a biogeography is the study of the distribution of biodiversity over space and time) division of the earth's surface based on the historic and evolutionary distribution patterns of plants and animals (c.f. Wikipedia). It represent large areas of the earth's surface where plants and animals developed in relative isolation over long periods of time, and are separated from one another by geologic features, such as oceans, deserts, or high mountain ranges, that formed barriers to plant and animal migration. The patterns of plant and animal distribution in the world's ecozones are shaped by the process of plate tectonic (a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere), which has redistributed the world's land masses over geological history. The WWF (World Wide Fund for Nature) divides the world into eight ecozones viz.
- Nearctic (including most of North America)
- Palearctic (including the bulk of Eurasia and North Africa)
- Afrotropic (including Sub-Saharan Africa)
- Indomalaya (including the South Asian subcontinent and Southeast Asia)
- Australasia (including Australia, New Guinea, and neighbouring islands).
- Neotropic (including South America and the Caribbean)
- Oceania (including Polynesia, Fiji and Micronesia)
- Antarctic (including Antarctica).