Biogeographical Regions

Abstract

Species are not uniformly distributed over the globe. The largest regions of animal and plant assemblages are biogeographical regions, each bearing a distinctive fauna and flora. Some families and even some orders of animals are endemic to particular biogeographical regions; other families are shared by two or more regions; a few families are cosmopolitan and found in all regions. The delineation of traditional biogeographical regions was rather subjective. Recently, increased availability of global species range maps, the development of new multivariate techniques and improved computational power have led to quantitative regionalisations that are broadly similar to traditional regions but do show differences. The transition zones between are sometimes gradual, as in the junction between the Oriental and Australian faunal regions. The state of biogeographical regions is under threat from such human activities as habitat destruction and fragmentation and the introduction of alien species, and it will decline without conservation measures.

Key Concepts:

  • Regions (in biogeography) are spatial units of varying scales carrying comparatively distinct sets of animals and plants.

  • Faunal and floral elements are groups of species sharing a similar pattern of geographical distribution.

  • Biogeographical provincialism is the tendency of different geographical regions to house unique species, genera or families.

  • Endemism is the state of being unique to a specific geographical region, such as a continental landmass, a biogeographical region or a habitat.

  • Transition zones (in biogeography) are regions where one biogeographical region grades into another, and contrasts with sharp borders.

  • The Great American Interchange was the intermingling of South American and North American faunas starting 6 million years ago when a string of islands and then a permanent land connection bridged the ocean gap between North American and South American landmasses.

  • Habitat loss and fragmentation is one of the chief drivers of biodiversity loss and change in biogeographical regions.

  • Alien species (also called exotic, introduced and nonnative species) are species accidentally or purposefully carried to areas outside their natural range by humans.

Keywords: endemics; fauna; flora; geographical distribution; mammals; plants

Figure 1.

The six faunal regions delimited by Sclater and Wallace.

Figure 2.

The six floral regions and 37 subregions mapped by Good.

Figure 3.

The four faunal regions and 10 subregions recognised by Smith.

Figure 4.

Dendrograms and maps resulting from UPGMA hierarchical clustering of grid cell assemblages of mammals. On the map, boundary widths are proportional to the height in the UPGMA dendrogram where adjacent groups merge. Modified Behrmann projection. Source: Adapted from Kreft and Jetz .

Figure 5.

Wallacea – the transition zone between the Oriental and Australian faunal regions.

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References

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Further Reading

Cox CB and Moore PD (2009) Biogeography: An Ecological and Evolutionary Approach, 8th edn. Oxford: Blackwell.

Feldhamer GA, Drickamer LC, Vessey SH, Merritt JF and Krajewski CW (2007) Mammalogy: Adaptation, Diversity, Ecology, 3rd edn. Baltimore: Johns Hopkins University Press.

Flynn JJ (2009) Splendid isolation: South America was an island for millions of years, fostering an evolutionary explosion of unique mammal species. Natural History 188: 26–32.

Huggett RJ (2004) Fundamentals of Biogeography, 2nd edn. London/New York: Routledge.

Lomolino MV, Riddle BR, Whittaker RJ and Brown JH (2010) Biogeography, 4th edn. Sunderland, MA: Sinauer Associates.

Wilson DE and Reeder DM (2005) Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd edn. Baltimore: Johns Hopkins University Press.

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How to Cite close
Huggett, Richard(Oct 2011) Biogeographical Regions. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003231.pub2]