| 李氏方法与Farris氏方法产生的分支系统树的比较 |
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| 引用本文： | 秦廷奎,段宇.李氏方法与Farris氏方法产生的分支系统树的比较[J].中国科学院研究生院学报,1993,31(1):100-104. |
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| 作者姓名： | 秦廷奎 段宇 |
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| 摘 要： | 中值淘汰法的主要目的是为了打破现代分支系统学中采用最简原理所带来的不确定性僵局。然而，在两个或两个以上分类单元都具有相同衍进指数的情况下，该方法也能不止产生一个分支系统树，因为没有一个客观标准来确定应该先连接哪一个分类单元，而连接的先后顺序不同，就会产生不同的分支系统树。中值淘汰法的作者认为，该法产生的结果不用简约性来判定。但是，该法也能构成最简约的分支系统树。本文还对应用中值淘汰法所面临的问题作了讨论。
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| 关 键 词： | 白粉藤属 泥炭藓属 分支系统学分析 李氏方法 中值淘汰法 Farris 氏方法 |
Comparison of the Cladograms Produced by Li's Method and Farris' Method |
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| Qin Ting-kui,Duan Yu.Comparison of the Cladograms Produced by Li's Method and Farris' Method[J].Journal of the Graduate School of the Chinese Academy of Sciences,1993,31(1):100-104. |
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| Authors: | Qin Ting-kui Duan Yu |
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| Abstract: | In order to avoid producing many equally most parsimonious trees,
Li (1990) developed a new cladistic method, the Median Elimination
Series (MES), to construct a single cladogram for a given data set. However, we
found that Li's method can produce more than one tree if two or more taxa have
the same advancement index (which is the total number of apomorphies for a
taxon in a given data set), because there is no objective method to decide which
taxon should be connected first and different orders of connection can produce
different trees.
Li claimed that the result produced by his method did not apply the principle
of simplicity (parsimony). Nevertheless, Zhang (1991) recognised that Li's meth-
od actually accepted the principle of parsimony. Here we demonstrated that Li's
method also can produce the minimum-length trees.
We conclude that Li's method could produce more than one tree and the tree(s)
may be the minimum-length possible. However, the length of tree(s) depends
on the order of connection of the taxa. The major problems in using Li's methodare discussed. |
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| Keywords: | Cissus Sphagnum Cladistic analysis Li's method Median Elimination Series (MES) Farris’ method |
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