Zoogeography(redirected from zoogeographical)
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the geography of animals; a branch of biology and physical geography concerned with the present and past geographic distribution of animals on the earth and the present and historical factors and lawlike regularities that determine this distribution and the geographic distribution of ecological groups of animals.
Zoogeography is closely related to a number of branches of biology, including taxonomy, paleontology, ecology, and plant geography, and to branches of physical geography such as paleogeography and landscape science. It is also related to historical geology and some of the humanities, including history, archaeology, and ethnology, which provide information on historical changes in the animal world.
Interest in zoogeography broadened with the publication of Darwin’s Origin of Species in 1859. The works of the British scientists P. Sclater (1859) and A. R. Wallace (1860-80), a founder of zoogeography, were very significant. In Russia a great deal of information about the distribution of animals was gathered before the reign of Peter I. A vast amount of factual material was collected in the 18th century, chiefly as a result of expeditions sponsored by the Russian Academy of Sciences and led by P. S. Pallas, I. I. Lepekhin, S. P. Krasheninnikov, I. G. Gmelin, and S. G. Gmelin. Considerable progress was made in the 19th century in gathering material and in generalizing from it. Contributions were made by the works of K. M. Baer, A. F. Middendorf, E. A. Eversman, lu. I. Semashko, N. A. Severtsov, G. I. Radde, and M. A. Menzbir, and later, by P. P. Sushkin and A. P. Semenov-Tian-Shanskii.
Aquatic fauna was studied from the zoogeographic point of view by the British scientist E. Forbes and the French scientist A. Milne-Edwards, and later, by the German A. Ortmann and the Swede S. Ekman. In the Soviet Union, zoogeographic studies of aquatic fauna were done by a number of scientists, including L. S. Berg, K. M. Deriugin, N. M. Knipovich, L. A. Zenkevich, E. F. Gur’ianova, and A. P. Andriiashev. Among the Soviet scientists who worked out the general principles of zoogeography were B. K. Shtegman, G. U. Lindberg, A. M. Nikol’skii, V. V. Stanchinskii, N. A. Bobrinskii, V. G. Geptner, and la. A. Birshtein. Intensive work is being done on some aspects of zoogeography in foreign countries. Comprehensive studies are being done of separate and particularly complicated faunal regions and complexes (the Indo- Malay an region, the New Guinea region and the adjacent islands, and South America). Major works have been written on zoogeography, including studies of the relationship between Eurasian and North American fauna, the fauna of the continents of the southern hemisphere, and the problem of refugees. The general principles of zoogeography are being elaborated by many scientists, including the Swedes F. Eckland and C. Lindroth, the Germans R. Hesse, F. Dahl,E. Markus,F. Schilder,and H. de Lattin, and the Americans P. Darlington, P. Hershkovitz, E. Mayr, G. Simpson, M. Udvardy, and R. Rausch.
Zoogeography has become extremely important in the Soviet Union because of the need to make full, efficient use of the country’s natural resources. Contemporary zoogeography is characterized by a broad use of data from allied disciplines, thorough study of the origin of faunas (historical zoogeography) and the relationship of animals to the landscape, and quantitative and biocenotic analysis of faunas and the distribution of species (ecological zoogeography).
One of the principal tools of zoogeography is cartography. All the known habitats of a species are plotted on a map to obtain the primary objective of zoogeography—the range of a species, which is as characteristic of and specific to a species as its morphological and other properties. Individual members of each species do not inhabit its entire range but are found only where the necessities of life prevail, in the habitats that are characteristic of the species. Like the relative abundance of population in various places, the distribution of a species within its own range (the so-called species topography) can be very uneven. Changes in the conditions of existence (for example, general changes in the climate, the development of favorable conditions in adjacent regions, the disappearance of a barrier) often cause a species to settle in a new place, to broaden or change its range, or to move to a new place. Often, when the conditions of existence are similar in different areas, one related species will replace another (vicarious species, geographic vicarious species).
By summarizing various data concerning the composition and distribution of species in a country, scientists achieve the second objective of zoogeography, which is to gain a general idea of a country’s fauna.
The third objective is to outline the ecological groupings (biogeocenoses) into which the species of a particular fauna fall, as well as the lawlike regularities of their distribution. Several categories of species may be distinguished in the fauna of each territory. Species found only in a particular region are called endemic species. They, in turn, may be divided into species that originated in the given territory (autochthons) and species that migrated from a neighboring region where they originated but where they no longer live (immigrants). For example, an endemic species of the Caucasus, the Caucasian ptarmigan, is also an autochthon, but horses, which are endemic to Asia and Africa, are immi-grants, because they originated in America, where they later became extinct.
The lawlike regularities of the formation of faunas are most pronounced in isolated land areas (island fauna) or in bodies of water. The fauna of a continental island (that is, an island that was once part of the continent and now lies close to it) is always similar to the fauna of the nearest continent. It differs mainly in the absence of certain species (the so-called rule of island impoverishment) and a greater number of endemic species, which is the result of speciation during geographical isolation. In general, the farther an island is from a continent, the more endemic species there are and the higher their taxonomic position. In the same climatic zone large islands usually have a richer fauna than small islands, where the conditions of existence are more uniform.
The fauna of oceanic islands (coral and volcanic types, such as Ascension, St. Helena, Tristan da Cunha, Hawaii, and the Galapagos), which consists of accidental allochthons, is “dysharmonious” and different from that of other types of islands. Groups of animals unable to travel across the ocean are generally absent on oceanic islands. There are no amphibians, freshwater fish, or mammals (except bats). The exceptions to this rule are due mainly to man, who has brought such species as rats, rabbits, and goats to many islands. Thus, the animal world of all the oceanic islands has been drastically changed.
Man is responsible for the last few centuries’ changes in the world’s fauna. Several species were exterminated by man and are now extinct (for example, the tarpan [a wild horse], dodo, and passenger pigeon and Steller’s sea cow). A large number of species are nearly extinct, are declining, or are changing their ranges because of man-made changes in nature, such as the plowing up of the steppes and the clearing of forests. However, many animals have adapted to coexistence with man. Some have become commensals or parasites (for example, house and tree sparrows, house mouse, black and brown rats, houseflies, and bedbugs), while others inhabit the so-called cultivated landscape created by man.
The historical analysis of faunas is very important for an understanding of their composition and formation. For example, African fauna includes a group of Gondwana relicts (Onychophora), Miocene Asiatic immigrants (elephants, okapis, and other animals of the humid tropical forest), and Pliocene species of the savannas (for example, antelope, zebras, and lions).
The historical examination of faunas reveals some information about the places of their development (the classifications “Siberian” and “Far Eastern,” for example) and about their movement—encroachment or retreat (for example, the encroachment of steppe fauna into areas cleared of forests). Minor and more or less gradual changes in a fauna may sometimes give way to substantial and rapid ones, which usually result from sharp environmental changes (for instance, changes in the climate or direction of sea currents). If two faunas that were once more or less completely separate come into contact, complex exchanges of constituents and mutual penetration or displacement occur. Individual elements of the displaced or for some reason extinct fauna may survive (relicts).
Zoogeography is very important for understanding and studying the factors in and modes of speciation. Most biologists believe that so-called geographic speciation, which is caused by territorial isolation of populations, is the main if not the only way in which new forms and species are created. Zoogeographic data are extremely important for geography and historical geology, especially that of the Anthropogenic period. Thus, facts and arguments from zoogeography play a major role in the study of such topics as the links between America and Asia, the history of the Pleistocene and Holocene ages, the history of the Antarctic, and the history of the oceans. Zoogeography also has substantial, practical significance for hunting and raising fur-bearing animals, trapping, whaling, and fishing. It contributes to the study of acclimatization, agricultural and forest pests, and the regulation of the numbers of injurious and useful animals, and it is important to conservation and other fields, such as veterinary science and medicine (the role of parasites and vectors of transmissible diseases and the natural focality of diseases, for example).
Zoological museums play an important part in collecting the facts that are needed to solve some of the problems of zoogeography. Aspects of zoogeography occupy a prominent place in the work of many scientific societies (for example, in the work of the Moscow Society of Naturalists), many biological congresses (general zoological) or specialized—entomological and ornithological, for example), and congresses on oceanography, geography and geology (particularly on the Anthropogenic system). All-Union congresses on zoology have been held regularly in the USSR since 1957. (Prior to 1972, five congresses were held at L’vov, Alma-Ata, Tashkent, Odessa, and Kazan. Surveys of the latest literature appear in such abstracts as Botanika i zoologiia (Botany and Zoology; since 1958)andBiogeografiia (Biogeography, since 1967). Articles on zoogeography are published in many non-periodical publications and in zoological, geographic, and other journals. The journal Zoogeographica was published in Germany from 1932 to 1942.
In the USSR a course in zoogeography is given in university biology and geography departments and in the corresponding departments of many pedagogical institutes. Some universities have biogeography subdepartments that offer courses in zoogeography.
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Geptner, V. G. Obshchaia zoogeografiia. Moscow-Leningrad, 1936.
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V. G. GEPTNER