Allopatry


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Related to Allopatry: sympatry
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Allopatry

 

a widely distributed type of species formation in which new species arise from populations with nonoverlapping areas. Any population or group of populations which has been isolated geographically for an extended period of time inevitably acquires specific characteristics associated with genetic changes, mainly with differences in the direction and intensity of natural selection. In the Galapagos Islands, for example, species of finches have appeared which have adapted to living on a particular food. Some of them have developed into insectivores, others into granivores. In this instance, territorial isolation favored the speedy rise of new species.

Interbreeding upon encounter, and consequently the exchange of genetic information and leveling of the differences which have appeared, cannot take place if the isolation of the allopatric groups is total and the deviation has become rooted in heredity. In such cases, allopatric forms are recognized as new species. For example, species of herring gulls interconnected by a chain of subspecies do not interbreed in the wild while intermingling in the Baltic area. Allopatry may be inherent in groups either above or below the species level. There are transitional stages between allopatry and sympatry.

REFERENCES

Cain, A. Vid i ego evoliutsiia. Moscow, 1958. (Translated from English.)
Zavadskii, K. M. Vid i vidoobrazovanie. Leningrad, 1968.
Mayr, E. Zoologicheskii vid i evoliutsiia. Moscow, 1968. (Translated from English.)

A. V. IABLOKOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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The question addressed here is whether species in the Maui Nui clade formed through diversification within the single volcano of East Maui or alternatively whether divergence occurred in allopatry, prior to their current distribution.
Distance (mean [+ or -] SE) between summer and winter locations (allopatry) and net displacement (ND; sensu Bunnefeld et al.
Despite the initial popularity of this concept of "character displacement," the phenomenon and its dual, "character release" (Grant 1972) in areas of allopatry from a competitor, were widely seen for many years as uncommon at best, and alternative explanations for geographic variation are often available (Grant 1972).
The increase in the number of described Hemibrycon species from the Cauca-Magdalena River system, most of which exist in allopatry, suggests an interesting model for diversification of this genus in the Andes (Roman-Valencia & Arcila-Mesa 2009).
xerampelinus occurs in allopatry (Volcan Baru and Cerro de la Muerte) or where the two species meet (Volcan Irazu).
The great variation in ecological conditions, displacement during climatic changes, fragmentation during geological events, as well as allopatry derived from a very complex orography may have favored differentiation of Phaulotettix spp., as has occurred in other insect groups.
Although these two taxa are not sister species and the boundary between the Great Fish and Kei catchments therefore not a vicariant feature contributing to speciation, it may well now limit dispersal and maintain the allopatry of these lineages.
Differentiated populations or incipient species currently separated by obvious geographic barriers provide some of the best evidence that allopatry is a common geographic mechanism of speciation (Mayr 1942; Carson and Kaneshiro 1976; Grant 1986; Lessios and Cunningham 1990; Knowlton et al.
Amaral's (1944) arrangement is not followed here because of the absence of allopatry among the color pattern types.