Zoogeography is a word made up of two parts: zoo (meaning living beings) + geography (the study of the earth’s surface). Zoogeography the study of geographical distribution of organisms about the globe.
Generally speaking, the earth is divided into 6 zoogeographical realms: the Nearctic, the Neotropical, the Palaearctic, the Ethiopian, the Oriental, and the Australasian. Look at their locations on this map.
Zoogeographical realms or regions are areas characterized by a collection of animals including species unique to a region. A zoogeographical region has some characteristics that distinguish it from other areas. Each realm can contain multiple sub-regions.
In general, different parts of the world have different types of organisms. These geographical differences are not haphazard or random. In general, continental regions have more or less uniform biotas (“biota” = the assemblage of organisms), but there are great differences among them. For example, marsupial (pouched) mammals are almost entirely restricted to Australasia. The biotas of some parts of the globe (e.g. South America and Australia) are much more unusual than others (e.g. North America and Eurasia have much in common). In general, many of the elements of the biotas of given continents were related to each other more closely that they were to elements from the biotas of other continents.
Geography plays a key role in the distribution of animals around the globe. The distribution of a species is a consequence of its:
- history
- ecological tolerances (which dictate where it can live)
- the geographical distribution of places satisfying these requirements
- barriers to dispersal
- interactions with other species
- chance
