Parsimony, Character-Polarization and Median Elimination Series—A Dissentation from Dr. Li

Zhang Dian-Xiang

Received:1900-01-01 Revised:1900-01-01 Online:1991-05-10 Published:1991-05-10
Contact: Zhang Dian-Xiang

Abstract:

The Median Elimination Series method differs from those of other cladists both

theoretically and technically. The principle of parsimony is one of the bases of scientific

hypotheses; the theory of evolution is the causal explanation relationships between

organisms. Both of them are the bases of cladistics. Thus it is implausible to replace the for-

mer by the latter.

Distinguishing a plesiomorphy from a reversion and a direct apomorphy from a cyclic

apomorphy as indicated by Dr Li (1990) in his character 5 and character ll, is difficult if not

impossible. So the basis of MES is vulnerable.

Using only 2 taxa in calculating the value of media and thus deciding the placement of a

taxon in a cladogram would bring uncertainties when reversion exists.

Morphological character homoplasy and reversion must be treated equally if Wagner's

parsimony principle is followed. But reversion is ignored in MES calculation.

Several more parsimonious cladograms are yielded with Dr Li's data when Farris's

method is followed.

MES is not a better alternative anyway.

Key words: Parsimony, Character-polarization, median elimination series

Zhang Dian-Xiang. Parsimony, Character-Polarization and Median Elimination Series—A Dissentation from Dr. Li[J]. .

[1]	Zhao Tie-qiao. Cladistic Patterns, Component Analysis and Median Elimination Series [J]. , 1997, 35(1): 88-96.
[2]	Qin Ting-kui, Duan Yu. Comparison of the Cladograms Produced by Li's Method and Farris' Method [J]. , 1993, 31(1): 100-104.
[3]	Li Chao-Luan. A New Method for Cladistic Analysis—Median Elimination Series (MES) [J]. , 1990, 28(1): 34-53.

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