Ecozones are a method of dividing up the Earth's surface. Each ecozone is a large area that contains a number of habitats, which are linked by the evolutionary history of the animals and plants within them. For instance one ecozone is Australasia, because its marsupials evolved in isolation to mammals in the rest of the world.

Map showing the location of the ecozones Nearctic Oceania Neotropic Afrotropic Palearctic Indomalaya Australasia Antarctic

To understand the diversity of life it is helpful to consider how natural boundaries, which exist now and in the geological past, have restricted movement and how different climates have lead to different environmental pressures. Both geographical isolation and differing environmental pressures have resulted in diversification through natural selection.

Different groups of species, and different types of solution have evolved in different parts of the world...