biogeography

A synthetic discipline that describes the distributions of living and fossil species of plants and animals across the Earth's surface as consequences of ecological and evolutionary processes. Biogeography overlaps and complements many biological disciplines, especially community ecology, systematics, paleontology, and evolutionary biology. See also Zoogeography.

Based on relatively complete compilations of species within well-studied groups, such as birds and mammals, biogeographers identified six different realms within which species tend to be closely related and between which turnovers in major groups of species are observed (see table). The boundaries between biogeographic realms are less distinct than was initially thought, and the distribution of distinctive groups such as parrots, marsupials, and southern beeches (Nothofagus spp.) implies that modern-day biogeographic realms have been considerably mixed in the past. See also Animal evolution; Paleobotany; Paleoecology; Paleontology; Plant evolution; Speciation.

Two patterns of species diversity have stimulated a great deal of progress in developing ecological explanations for geographic patterns of species richness. The first is that the number of species increases in a regular fashion with the size of the geographic area being considered. The second is the nearly universal observation that there are more species of plants and animals in tropical regions than in temperate and polar regions.

In order to answer questions about why there are a certain number of species in a particular geographic region, biogeography has incorporated many insights from community ecology. Species number at any particular place depends on the amount of resources available there (ultimately derived from the amount of primary productivity), the number of ways those resources can be apportioned among species, and the different kinds of ecological requirements of the species that can colonize the region. The equilibrium theory of island biogeography arose as an application of these insights to the distribution of species within a specified taxon across an island archipelago. This theory generated specific predictions about the relationships among island size and distance from a colonization source with the number and rate of turnover of species. Large islands are predicted to have higher equilibrium numbers of species than smaller islands; hence, the species area relationship can be predicted in principle from the ecological attributes of species. Experimental and observational studies have confirmed many predictions made by this theory. See also Ecological communities; Island biogeography.

The latitudinal gradient in species richness has generated a number of explanations, none of which has been totally satisfactory. One explanation is based on the observation that species with more temperate and polar distributions tend to have larger geographic ranges than species from tropical regions. It is thought that since species with large geographic ranges tend to withstand a wider range of physical and biotic conditions, this allows them to penetrate farther into regions with more variable climates at higher latitudes. If this were true, then species with smaller geographic ranges would tend to concentrate in tropical regions where conditions are less variable. While this might be generally true, there are many examples of species living in high-latitude regions that have small geographic regions. See also Altitudinal vegetation zones.

Biogeography is entering a phase where data on the spatial patterns of abundance and distribution of species of plants and animals are being analyzed with sophisticated mathematical and technological tools. Geographic information systems and remote sensing technology have provided a way to catalog and map spatial variation in biological processes with a striking degree of detail and accuracy. These newer technologies have stimulated research on appropriate methods for modeling and analyzing biogeographic patterns. Modern techniques of spatial modeling are being applied to geographic information systems data to test mechanistic explanations for biogeographic patterns that could not have been attempted without the advent of the appropriate technology. See also Geographic information systems.

The study of the distribution of life forms, past and present, and the causes of such distributions. It includes the application of biochemical techniques for genetic analysis and application to the large-scale analysis, incorporating remote sensing, of biogeographical patterns; studying and modelling ecosystem dynamics and metapopulation dynamics; problems of speciation and genotypic variation; and the analysis and dating of the palaeo-biogeographical record. Biogeographers may also be concerned with environment-related food and health issues.

Biogeography is the study of the distribution, both current and past, of individual species in specific environments. One of the first biogeographers was Carolus Linnaeus (1707-1778), a Swedish botanist who studied the distribution of plants. Biogeography specifically addresses the questions of evolution, extinction, and dispersal of organisms in specific ecosystems.

Scientific study of the geographic distribution of living organisms.

Biogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance.^[1]

Biogeography does more than ask Which species? and Where. It also asks Why? and what is sometimes more crucial, Why not?. ^[2]

The patterns of species distribution at this level can usually be explained through a combination of historical factors such as speciation, extinction, continental drift, glaciation (and associated variations in sea level, river routes, and so on), and river capture, in combination with the area and isolation of landmasses (geographic constraints) and available energy supplies.

Modern biogeography often employs the use of Geographic Information Systems (GIS), to understand the factors affecting organism distribution, and to predict future trends in organism distribution. ^[3] Often mathematical models, and GIS are employed to solve ecological problems that have a spatial aspect to them. ^[4]

Contents 1 History 2 Paleobiogeography 3 Classification 4 See also 5 Notes and References 6 Further reading 7 External links 7.1 Major journals

History

The scientific theory of biogeography grows out of the work of Alfred Russel Wallace and other early evolutionary scientists. Wallace studied the distribution of flora and fauna in the Malay Archipelago in the 19th century. With the exception of Wallace and a few others, prior to the publication of The Theory of Island Biogeography by Robert MacArthur and E.O. Wilson in 1967^[5] the field of biogeography was seen as a primarily historical one and as such the field was seen as a purely descriptive one.

MacArthur and Wilson changed this perception, and showed that the species richness of an area could be predicted in terms of such factors as habitat area, immigration rate and extinction rate. This gave rise to an interest in island biogeography. The application of island biogeography theory to habitat fragments spurred the development of the fields of conservation biology and landscape ecology.^[6]

Classic biogeography has been expanded by the development of molecular systematics, creating a new discipline known as phylogeography. This development allowed scientists to test theories about the origin and dispersal of populations, such as island endemics. For example, while classic biogeographers were able to speculate about the origins of species in the Hawaiian Islands, phylogeography allows them to test theories of relatedness between these populations and putative source populations in Asia and North America.

Paleobiogeography

Paleobiogeography goes one step further to include paleogeographic data and considerations of plate tectonics. Using molecular analyses and corroborated by fossils, it has been possible to demonstrate that perching birds evolved first in the region of Australia or the adjacent Antarctic (which at that time lay somewhat further north and had a temperate climate). From there, they spread to the other Gondwanan continents and Southeast Asia - the part of Laurasia then closest to their origin of dispersal - in the late Paleogene, before achieving a global distribution in the early Neogene (Jønsson & Fjeldså 2006). Not knowing the fact that at the time of dispersal, the Indian Ocean was much narrower than it is today, and that South America was closer to the Antarctic, one would be hard pressed to explain the presence of many "ancient" lineages of perching birds in Africa, as well as the mainly South American distribution of the suboscines.

Classification

Biogeography is a synthetic science, related to geography, biology, soil science, geology, climatology, ecology and evolution.

Some fundamentals in biogeography are

• evolution (change in genetic composition of a population)
• extinction (disappearance of a species)
• dispersal (movement of populations away from their point of origin, related to migration)
• range and distribution
• endemic areas
• vicariance

See also

Environment portal

Ecology portal

Earth sciences portal

• Ecozone (biogeographic region or biogeographical realm)
• Ecological land classification
• Ecoregion
• Gravity model of migration, pertaining to Distance decay
• Macroecology
• Phylogeography
• Zoogeography
  • Zoogeographic province
• Phytogeography
  • Floristic province
• Continental drift
  • Alfred Wegener
• Tectonic plates
• Alfred Russel Wallace
  • Wallacea
• Charles Darwin
• Miklos Udvardy
• Important publications in biogeography

Notes and References

1. ^ Martiny JBH et al. Microbial biogeography: putting microorganisms on the map Nature: FEBRUARY 2006 | VOLUME 4
2. ^ The song of Dodo: Island Biogeography in an age of extinctions by David Quammen 1996 Pub Scribner, New York ISBN 0-684-80083-7
3. ^ Cavalcanti, Mauro. (2009). Biogegraphy and GIS. http://digitaltaxonomy.infobio.net/?Software:Biogeography_and_GIS
4. ^ Whittaker, R. (1998). Island Biogeography: Ecology, Evolution, and Conservation. Oxford University Press. New York.
5. ^ This work expanded their 1963 paper on the same topic.
6. ^ This applies to British and American academics; landscape ecology has a distinct genesis among European academics.

Further reading

• Jønsson, Knud A. & Fjeldså, Jon (2006). Determining biogeographical patterns of dispersal and diversification in oscine passerine birds in Australia, Southeast Asia and Africa. Journal of Biogeography 33(7): 1155–1165. doi:10.1111/j.1365-2699.2006.01507.x (HTML abstract)
• Dansereau, Pierre (1957). Biogeography: An Ecological Perspective. New York City: Ronald Press Company. ISBN 0826023304. 
• MacArthur, Robert H. (1972). Geographic Ecology. New York: Harper & Row. 

External links

• International Biogeogaphy Society
• Systematic & Evolutionary Biogeographical Society
• Early Classics in Biogeography, Distribution, and Diversity Studies: To 1950
• Early Classics in Biogeography, Distribution, and Diversity Studies: 1951-1975
• Some Biogeographers, Evolutionists and Ecologists: Chrono-Biographical Sketches

Major journals

• Journal of Biogeography homepage.
• Global Ecology and Biogeography homepage.
• Ecography homepage.

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v • d • e Biogeography Phylogeography · Zoogeography · Phytogeography · Island biogeography · Palaeobiogeography · Panbiogeography

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