Parsimony, Character-Polarization and Median Elimination Series—A Dissentation from Dr. Li-文献传递-植物通论文库

作者：Zhang Dian-Xiang

期刊：植物分类学报 1991年 3期

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.

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