限界 (分類学)




分類学において、分類群(タクソン)の限界とは、その分類群が指し示す範囲の定義のことである[1]。



概要


分類学における目標の1つは、すべての分類群に対し安定した限界を設けることである。ほとんどの分類群の限界はまだ安定したものではなく、分子系統学の急速な発展に伴い、安定した限界をもつと数十年にわたって見なされていた分類群についてもその多くで激変が起きている。 新しい発見により、既存の限界に用いられていた特徴が実際は関連性を持たない無効なものとして否定されたり、分岐学の結果を裏付ける特徴が新しく提示されたりする場合がある。


例えば、かつて安定していなかった系統群の1つとして被子植物のウルシ科がある。その一部は、Blepharocaryaceae、Julianaceae、Podoaceaeといった異なる科に所属していた[2]が、現在学術的に用いられるAPG体系では、2003年のAPG II発表以来2016年発表のAPG IVに至るまで1つの科としてまとめている[3]。



脚注





  1. ^ 露崎史朗 (2013年1月5日). “植物分類学”. 北海道大学. 2016年10月14日閲覧。


  2. ^ Anacardiaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants.


  3. ^ Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 [and more or less continuously updated since].




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