When an organism's environmental conditions change and a mutation has already occurred that allows it to adapt to the change, the organism is said to be preadapted. This term was coined by French evolutionist L. Cuénault. Current orthodox evolutionary theory states that evolution occurs when advantageous mutations that suit the environment are selected, so from one perspective, evolution can even be seen as the accumulation of tiny preadaptations. For example, if a mutant of water fleas occasionally appears that is suited to temperatures lower than the water temperature of a pond, and if the water temperature of the pond drops for some reason, this mutant will establish itself as the new dominant group. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
生物にとっての環境条件が変化した際,それに適応するような変異があらかじめ生じていたとき,その生物は前適応していたといわれる。フランスの進化学者 L.キュエノーの造語。現行の正統進化理論では,環境に合う有利な突然変異が選び出されて進化が生じるとしているので,進化は,ある見方ではすべて微小な前適応の集積ということにさえなる。たとえばミジンコのなかに,池の水温よりも低い温度に適する変異体がときどき現れるとして,ある原因からその池の水温が低くなれば,この変異体が新しい優勢な群として確立する。
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