An evolutionary phenomenon proposed by H. Osborn (1917). When the same original species lives in a variety of different environments, it undergoes physiological and morphological differentiation suited to each environment, splitting into many different lineages. This effect intensifies over time. This phenomenon has occurred many times throughout geological time, with reptiles and mammals dispersing into terrestrial, underground, aquatic, semi-aquatic, arboreal, and aerial habitats, and into herbivorous, carnivorous, and omnivorous diets. The many species of marsupials on the Australian continent and the prosimians of Madagascar are famous examples, showing that adaptive radiation can progress significantly when organisms are placed in closed environments. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
H.オズボーンにより提唱された (1917) 進化の現象。同一の原種生物が,種々の異なった環境にすむと,それぞれの環境に適した生理的,形態的分化を起し,多数の異なった系統に分れること。時間の経過とともにその効果は強まる。この現象は地質時代を通じて数多く起り,爬虫類や哺乳類について,生活の場所に関しては地上,地下,水中,半水中,樹上,空中に,また食性については草食,肉食,雑食などに放散した。オーストラリア大陸での多種類の有袋類,マダガスカル島の原猿類は例として有名で,生物が閉鎖的環境におかれると適応放散が著しく進むことが示される。
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