Biogeography

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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.

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 Animal evolution, 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 Ecological communities, Island biogeography

Biogeographic realms
Continental areas Examples of distinctive
Realm included or endemic taxa
Palearctic Temperate Eurasia and Hynobiid salamanders
northern Africa
Oriental Tropical Asia Lower apes
Ethiopian Sub-Saharan Africa Great apes
Australian Australia, New Guinea, Marsupials
and New Zealand
Nearctic Temperate North America Pronghorn antelope,
ambystomatid salamanders
Neotropic Subtropical Central America Hummingbirds, antbirds,
and South America marmosets

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.

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.

Biogeography

 

the study of the laws governing the distribution of various biocenoses and also of animals, plants, and microorganisms (species, genera, and other taxonomic categories). Biogeography is an interdisciplinary science on the border line between biology and geography. Among its divisions are the geography of organisms, including the geography of microorganisms, the geography of plants, the geography of animals, and the general geography of organisms; and the geography of vegetational cover and of animal populations, including the geography of microbiocenoses, the geography of phytocenoses (vegetation), the geography of zoocenoses (animal populations), and the geography of biocenoses.

Some authors (the French scientist E. Martonne, the Soviet scientist V. G. Geptner, the Czech scientist F. Vitásek, and the Finnish researchers L. Aario and C. Janus) feel that biogeography is merely the combination of botanical geography and zoogeography; others (the Soviet scientist V. B. Sochava) think that biogeography is a kind of superstructure above these sciences which studies the most general laws of the geography of the organic world.

The various subdivisions of biogeography have evolved at different rates. By the beginning of the 19th century much information about animal and plant geography had been accumulated. The work of the German scientist A. Humboldt at the beginning of the 19th century laid the foundation for the study of the geography of phytocenoses. This study achieved considerable success at the end of the second half of the 19th century in the work of the Russian scientist I. G. Borshchov, the German scientists A. Schimper and A. Grisebach, the Danish scientist E. Warming, and others. At the end of the 19th century and beginning of the 20th century, certain problems of the geography of biocenoses were worked out by the Polish scientist J. K. Paczoski and the Russian scientists G. F. Morozov and V. N. Sukachev, and some problems of the geography of zoocenoses were worked out by the German scientists E. Jaeger and F. Dahl, the American scientists E. Forbes and V. Shelford, and others. The geography of microorganisms and microbiocenoses arose in the 20th century; these divisions of biogeography are among the most weakly developed. The tasks of biogeography were formulated by the German scientist A. Brauer (1914). Recapitulatory works on biogeography have been published by the Canadian scientist P. Dansereau (1957) and the Soviet scientist A. G. Voronov (1963). Works on the application of biogeography to a specific territory have been published by S. D. Matvejev (1961). Numerous studies have been devoted to the biogeography of the world ocean and its parts (for example, by the Soviet scientist L. A. Zenkevich, 1963).

There are many major fields of biogeography in which specific successes have been achieved: chorologic, floral and faunal, regional, and ecological and historical biogeography. In the field of chorology, ranges (distribution areas) of a significant number of species have been established. The study of the laws governing the distribution of species within the confines of the ranges has been undertaken; methods for mapping the ranges and their structure and, in particular, methods of compiling reference and cadastral maps have been devised. Floral and faunal studies have not covered all taxonomic groups to the same degree; a large part of the classes of invertebrates and lower plants has received relatively little study. Biogeography is beginning to study the distribution of the geographical elements of fauna and flora according to communities (for example, nemoral fauna and flora) and also the degree of participation of these elements in various communities (forest, steppe, meadow, and so on). With the isolation of floral and faunal regions, regional biogeography has confronted the necessity of taking into account not only the endemic taxa but also the taxa which are characteristic of a given region, in addition to appraising the abundance of individuals of various species. Large regions (areas and subareas) which are common to all taxonomic groups of animals, plants, and microorganisms have been discovered; however, the isolation of smaller regions (neighborhoods and sections) is not always possible because different groups of organisms which are distinct from each other in their nutritional habits and in other peculiarities are also governed by different laws of distribution. In ecological biogeography the study of biomasses, biological productivity, and the role of organisms in the life of natural-territorial systems and, in particular, in the transformation of energy has become increasingly important. From this perspective the different ecological groups of organisms which make up a community, their significance in the structure of the community, and the geographical peculiarities of interaction between organisms are studied. The study of the biogeographical aspects of human influence on organisms is of special importance. Historical biogeography studies the influence of the earth’s geological past on the present-day distribution of biocenoses and organisms. The reliability of historical-biogeographical theories depends on the reliability of the hypotheses which they use concerning change in the structure of the earth and its organic world throughout geological history.

The methods of biogeography are comparative geographical (the comparison of peculiarities of the fauna, flora, vegetational cover, and animal population of various natural-territorial systems), ecological (the determination of the interaction between the organic world and other components of natural-territorial systems), quantitative (the determination of the laws of distribution of biomasses and biological production), historical, and cartographic.

Biogeography is one of the sciences of the biosphere, the study of which was begun by V. I. Vernadskii. It is closely linked with biocenology, ecology, and biogeocenology. The objects of study of biogeography and biocenology overlap partially; biogeography also includes the geography of biocenoses (along with other subdivisions).

Biogeography provides the theoretical basis for the rational use of the resources of vegetational cover and animal populations by devising norms and time limits to the use of resources in accordance with the peculiarities of the geographical environment. The hunting of furbearing animals and game, the harvesting of plants for medicinal and industrial use, and the use of fodder grasses are impossible without a knowledge of the abundance, growth of populations, and other quantitative indicators in different regions. The development of means of combating agricultural and forest pests and the agents and carriers of many human diseases depend, to a large extent, upon a knowledge of the specifics of their distribution and the quantitative laws of their distribution within an area. The correct organization of measures to preserve nature depends on the study of the biogeographical characteristics of different zones and physicogeographical areas.

In the USSR there are subdepartments of biogeography at Moscow and Leningrad universities and in the Department of Biogeography in the Institute of Geography of the Academy of Sciences of the USSR; biogeographical commissions work within the All-Union Geographical Society and its Moscow branch. Biogeography is taught in departments of geography at universities. The All-Union Institute of Scientific and Technical Information (VINITI)) issues the abstract journal Biogeografiia.

REFERENCES

Geptner, V. G. Obshchaia zoogeografiia. Moscow, 1936.
Voronov, A. G. Biogeografiia. Moscow, 1963.
Voronov, A. G. “Nekotorye problemy biogeografii sushi.” Vestnik MGU: Geografiia, 1968, no. 5.
Zenkevich, L. A. Biologiia morei SSSR. Moscow, 1963.
Naumov. G. V. Kratkaia istoriia biogeografii. Moscow, 1969.
Die Kultur der Gegenwart. Published by Paul Hinneberg. Part 3, section 4, vol. 4. Leipzig, 1914.
Dansereau, P. Biogeography: An Ecological Perspective. New York, 1957.
Matvejev, S. Biogeografiia Jugoslavije: Osnovni principi. Belgrade, 1961.
See also references in the article.

A. G. VORONOV

biogeography

[¦bī·ō·jē′äg·rə·fē]
(ecology)
The science concerned with the geographical distribution of animal and plant life.
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