Lecointre G, Philippe H, Vân Lê H L, Le Guyader H
Laboratoire d'Ichtyologie générale et appliquée (GDR 1005), Muséum National d'Histoire Naturelle, Paris, France.
Mol Phylogenet Evol. 1993 Sep;2(3):205-24. doi: 10.1006/mpev.1993.1021.
Representative properties of gnathostome species of a rich 28S rRNA data base were studied through the analysis of the fluctuations they provoked in bootstrap proportions (BPs) of nodes of parsimonious trees. Using original programs which permit BP comparison between different trees, it is empirically demonstrated that 4- to 24-species-trees are highly sensitive to species sampling: the inferences obtained from subsets of 4, 8, 16, or 24 species are not congruent with the whole set of 31 species. Study of trees obtained from exhaustively sampling all combinations of single species taken from each presumed monophyletic group shows precisely the impact of each species on the BP of each node. This procedure also shows that the impact of species changes within a given group on tree BPs is localized to its two or three neighboring nodes. The observation of differing impacts of species emphasizes the importance of sampling several species per presumed monophyletic group. It is also concluded that it is necessary to sample several successive outgroups and that the impact of a species on BPs depends mainly on the sampling context. Before undertaking extensive sequencing, the impact of species should be more often considered, since its effect on BPs is stronger than previously thought.
通过分析28S rRNA丰富数据库中硬骨鱼物种在简约树节点的自展比例（BPs）中引起的波动，研究了这些物种的代表性特征。使用允许在不同树之间进行BP比较的原始程序，通过实验证明，4至24个物种的树对物种采样高度敏感：从4、8、16或24个物种的子集得出的推论与31个物种的整个集合不一致。对从每个假定的单系类群中逐个物种的所有组合进行详尽采样得到的树的研究，精确地显示了每个物种对每个节点BP的影响。该过程还表明，给定类群内物种变化对树BP的影响局限于其两三个相邻节点。物种不同影响的观察强调了在每个假定的单系类群中采样多个物种的重要性。还得出结论，有必要对几个连续的外类群进行采样，并且一个物种对BP的影响主要取决于采样背景。在进行广泛测序之前，应更频繁地考虑物种的影响，因为其对BP的影响比以前认为的更强。
