founder principle

Japanese: founder principle（英語表記）founderprinciple

…In a finite population, random drift works independently of natural selection, but its effect becomes more pronounced when the effect of natural selection is relatively small and the population's number of individuals is small. The bottle neck effect, which states that if the population's number of individuals becomes very small even once, the genetic composition of the population will be strongly influenced by that time, and the founder principle, which states that the genetic composition of a newly formed small population that splits off from a large population will have a lasting effect, are also aspects of random drift. The importance of random drift as a basic theory of the neutral theory of molecular evolution is becoming widely recognized. …

From [Speciation]

…The elucidation of the process and mechanism of speciation is one of the central issues in evolutionary science. Mayr's "founder principle" asserts that when a small population at the edge of a species' distribution is geographically isolated from the main population of the species (in such a case, the relationship between the main population and the marginal population is called allopatric. Conversely, when the two populations coexist in the same area, the relationship between the two is called sympatric), and the exchange of genes is cut off, natural selection and random drift of genes according to the local environment work effectively, and new species are formed relatively rapidly. This principle is supported by many scholars. …

*Some explanations of terms that refer to "founder principle" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…機会的浮動は有限集団であれば，自然淘汰とは独立に働くが，その効果が顕著に現れるのは自然淘汰の効果が相対的に小さく，集団の個体数が小さくなったときである。集団の個体数が一度でもひじょうに小さくなれば，集団の遺伝的組成はそのときの影響を強くうけるという瓶首効果bottle neck effectや，大集団から分かれて新たにできた小集団では創始時の遺伝的組成が，後々まで影響を及ぼすという創始者原理founder principleも機会的浮動の一面である。また機会的浮動は分子進化の中立説の基礎理論としてその重要性が広く認められつつある。…

【種分化】より

…種分化の過程と機構の解明は進化学の中心的課題の一つである。マイヤーE.Mayrの〈創設者の原理founder principle〉は，分布の縁辺部で小さな集団が地理的に種の主要な集団から隔離され(このような場合の主要な集団と縁辺の集団の関係を異所的という。逆に両集団が同一地域に共存する場合には両者の関係を同所的という)，遺伝子の交流が断たれることにより，その場の環境に応じた自然淘汰と遺伝子の機会的浮動が効果的に働き，比較的急速に新種が形成されることを主張するもので，多くの学者の賛同を得ている。…

※「founder principle」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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