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In evolutionary biology, a key Innovation, also known as an adaptive breakthrough or key adaptation, is a novel phenotypic trait that allows subsequent radiation and success of a taxonomic group. Typically they bring new abilities that allows the taxa to rapidly diversify and invade niches that were not previously available. The phenomenon helps to explain how some taxa are much more diverse and have many more species than their sister taxa. The term was first used in 1949 by Alden H. Miller who defined it as "key adjustments in the morphological and physiological mechanism which are essential to the origin of new major groups",〔 〕 although a broader, contemporary definition holds that "a key innovation is an evolutionary change in individual traits that is causally linked to an increased diversification rate in the resulting clade".〔 The theory of key innovations has come under attack because it is hard to test in a scientific manner, but there is evidence to support the idea. ==Mechanism== The mechanism by which a key innovation leads to taxonomic diversity is not certain but several hypotheses have been suggested:〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Key innovation」の詳細全文を読む スポンサード リンク
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