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Local adaptation: clean up, typo(s) fixed: ’s → 's

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In [[biology]], a '''deme''', in the strict sense, is a group of individuals that belong to the same [[taxonomic group]].<ref name=":1">Gilmour, J. S., & Heslop-Harrison, J. (1955). The deme terminology and the units of micro-evolutionary change. ''Genetica, 27''(1), 147-161.</ref> However, when biologists, and especially ecologists, use the term ‘deme’ they usually refer to it as the definition of a gamodeme:<ref>Winsor, M. P. (2000). Species, Demes, and the Omega Taxonomy: Gilmour and The NewSystematics. ''Biology and Philosophy, 15''(3), 349-388.</ref> a local group of individuals (from the same taxon) that interbreed with each other and share a [[gene pool]].<ref name=":1" /> The latter definition of a deme is only applicable to [[Sexual reproduction|sexual reproducing]] species, while the former is more neutral and also takes [[Asexual reproduction|asexual reproducing]] species into account, such as certain plant species. In the following sections the latter (and most frequently used) definition of a deme will be used.

In [[evolutionary computation]], a "deme" often refers to any isolated [[subpopulation]] subjected to [[natural selection|selection]] as a unit rather than as individuals.

== Local adaptation ==
A [[population]] of a species usually has multiple demes. Environments between these demes can differ. Demes could, therefore, become [[Local adaptation|locally adapted]] to their environment. A good example of this is the Adaptive Deme Formation (ADF) hypothesis in [[insect]]s.<ref name=":0">Zandt, P. A. V., & Mopper, S. (1998). A meta-analysis of adaptive deme formation in phytophagous insect populations. ''The American Naturalist, 152''(4), 595-604.</ref> The ADF hypothesis states that herbivorous insects can become adapted to specific host plants in their local environment because local plants can have unique nutrient patches to which insects may become adapted. This hypothesis predicts that less mobile insect demes are more likely to become locally adapted than more dispersive insect. However, a [[meta-analysis]], based on 17 studies on this subject, showed that dispersive insect demes were as likely to become locally adapted as less mobile insects.<ref name=":0" /> Moreover, this study found a small indication that feeding [[Behavior|behaviour]] might stimulate the local adaptation of demes. Endophagous insects were more likely to become locally adapted than exophagous insects. The explanation for this could be that endophagous insects come in more close and continuous contact to the plant's mechanical, chemical and phenological [[Plant defense against herbivory|defensive mechanisms]].<ref name=":0" />

== Speciation and demes ==
[[Speciation]] could occur at the level of demes. When a deme gets geographically isolated from other demes of the same species, [[Gene flow|gene-flow]] between these demes will stop which could lead to speciation after a long time. This is called [[allopatric speciation]] and is generally a slow process.<ref>Carson, H. L. (1987). The genetic system, the deme, and the origin of species. ''Annual review of genetics, 21''(1), 405-423.</ref>

On the contrary, [[sympatric speciation]] can be more rapid when a species has multiple small demes.<ref name=":2">Bush, G. L., Case, S. M., Wilson, A. C., & Patton, J. L. (1977). Rapid speciation and chromosomal evolution in mammals. ''Proceedings of the National Academy of Sciences, 74''(9), 3942-3946.</ref> This rapid speciation is both observed in plants<ref>Levin, D. A., & Wilson, A. C. (1976). Rates of evolution in seed plants: net increase in diversity of chromosome numbers and species numbers through time. ''Proceedings of the National Academy of sciences, 73''(6), 2086-2090.</ref> and vertebrates.<ref name=":2" /> Rapid speciation is explained by the [[ecology]] and [[Mating system|social structure]] of demes. Species that behave more territorial, live in patchy environments and/or have a [[Polygyny in animals|polygynous]] breeding system with only one reproductive male tend to have smaller deme sizes. Interbreeding between small demes is rare due to these factors. Furthermore, [[allele]]s fixate more rapidly in smaller demes. Small demes could, therefore, become genetically distinct from each other.<ref name=":2" />

[[Primate]]s, for example, have the second highest speciation rate among mammals, with one speciation event per lineage every 3 million years.<ref name=":2" /> However, not all primate species have a high speciation rate; this is reflected in their deme size and social structure. Guenons (''[[Guenon|Cercopithecus]]''), for example, live together in small polygynous troops and are a quite diverse [[genus]]. On the other hand, baboons (''[[Baboon|Papio]]'') have a much lower speciation rate. Baboons have larger deme sizes because they live in polygynous multi-male troops. These baboon demes are usually allopatric but gene-flow still exists between demes with [[Hybrid (biology)|hybridization]] being common.<ref name=":2" />

==Examples==
Various populations of [[gorilla]]s can be understood by their geographical separation and have been assessed to determine distinct and disjointed gene pools.<ref>Andrea Beth Taylor and Michele Lynn Goldsmith (2003) ''Gorilla Biology: A Multidisciplinary Perspective'', Cambridge University Press, 508 pages {{ISBN|0-521-79281-9}}, {{ISBN|978-0-521-79281-3}}</ref> The [[polar bear]], ''Ursus maritimus'', is understood to have 19 identifiable demes, even though their circumpolar distribution allows some interchange among the demes.<ref>C. Michael Hogan (2008) [https://web.archive.org/web/20081224205716/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=36084 ''Polar Bear: Ursus maritimus'', Globaltwitcher.com, ed. Nicklas Stromberg]</ref>

== See also ==
* [[Fragmented habitat]]
* [[Population genetics]]
* [[Memetics]]

==References==
{{reflist}}

[[Category:Genetics]]

Deme (biology) - История изменений

Admin: 1 версия импортирована

ru>Dancing Dollar: /* Local adaptation */clean up, typo(s) fixed: ’s → 's