This is due to a paucity of reliable evidence on the comparative advantages of the various species combination . 原因是缺乏对各种混合种类相对利益的可靠证明。
2.
Constant companions are added to the character taxa to form the " characteristic species combination " for associations and higher taxa 恒有伴生种加特征种构成群丛或更高级分类单位的“特征种组合” 。
