Summary
Wallace's realms divide the Earth by distinctive faunas shaped by plate tectonics and dispersal.
In depth
Wallace divided the world into Nearctic, Palearctic, Neotropical, Afrotropical, Oriental, Australasian and others. Wallace's Line separates Asian and Australasian fauna. Plate tectonics explains the distribution of marsupials and ratites.
Realms reflect evolutionary history and barriers. Continental drift separated faunas. Wallace's line marks sharp faunal change.
Remember: biogeography combines ecology and history.
Alfred Russel Wallace, in 1876, divided the world into zoogeographic realms based on distinctive animal groups: Palearctic, Nearctic, Neotropical, Afrotropical (Ethiopian), Indomalayan (Oriental), Australasian and Oceanian, with Antarctic. Botanical equivalents are floristic kingdoms.
The patterns result from continental drift, which isolated landmasses such as Australia (marsupials, monotremes) and South America, and from dispersal across land bridges, climate and barriers. Wallace's Line, between Bali and Lombok and between Borneo and Sulawesi, marks an abrupt faunal change in Southeast Asia due to deep water. Modern analyses using phylogenies refine the realm boundaries.
Example: marsupials are concentrated in Australasia and the Americas because of Gondwana's breakup.
Frequently asked questions
What is Biogeographic Regions?
Wallace's realms divide the Earth by distinctive faunas shaped by plate tectonics and dispersal.
Which area of biology covers Biogeographic Regions, and how advanced is it?
Biogeographic Regions is one of the 52 topics in Taxonomy & Biodiversity. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Species Delimitation, Hybridisation and Species Boundaries, Linnaeus.
Why does Biogeographic Regions matter?
Historical biogeography explains why similar environments hold different species.
Can you give an example of Biogeographic Regions?
Madagascar's lemurs result from long isolation.
What should I learn before Biogeographic Regions?
Work through the Beginner topics in Taxonomy & Biodiversity first, such as Taxonomy, Binomial Nomenclature, Taxonomic Hierarchy, then return to Biogeographic Regions. Advanced topics assume the Intermediate vocabulary.
What topics are related to Biogeographic Regions?
The closest topics to Biogeographic Regions are Species Delimitation, Hybridisation and Species Boundaries, Linnaeus, Community Phylogenetics. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Biogeographic Regions?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Biogeographic Regions. To practise the whole of Taxonomy & Biodiversity, use the Taxonomy & Biodiversity quiz.
How is Biogeographic Regions different from Species Delimitation?
Biogeographic Regions: Wallace's realms divide the Earth by distinctive faunas shaped by plate tectonics and dispersal. Species Delimitation: Methods integrating morphology, genetics and ecology to decide where species boundaries lie. Read both side by side and note what each one explains.
How should I study Biogeographic Regions step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Species Delimitation and explain the difference aloud. Finally, take the Taxonomy & Biodiversity quiz and come back to this page for any question you miss.