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New Measurements of Distribution of Homoplasy and Reliability of Parsimonious Cladograms
Vol. 44, No. 1 (Feb., 1995), pp. 77-82
Published by: International Association for Plant Taxonomy (IAPT)
Stable URL: http://www.jstor.org/stable/1222680
Page Count: 6
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Levels of homoplasy, measured by consistency index (CI) or retention index (RI), have been commonly used as indicators of reliability of parsimonious cladograms. Less attention has been paid to distribution of homoplasy which, however, may be another important parameter for estimating the reliability of cladograms. Average unit character consistency (AUCC), measuring distribution of homoplasy among the characters on parsimonious cladograms, is defined as the average of total unit character consistencies. When cladograms with the same CI are compared, the one with the largest AUCC also has the most asymmetric distribution of homoplasy, i.e., it is compatible with the largest portion of the characters, and homoplasy is concentrated in the smallest portion of cladistically unreliable or fast evolved characters of this cladogram. Homoplasy distribution index (HDI) is defined as the difference between the AUCC and CI, and can be used to compare distribution of homoplasy among cladograms with similar levels of homoplasy. A new measurement of the reliability of parsimonious cladograms, homoplasy distribution ratio (HDR), is defined as the ratio of the HDI to the homoplasy index (HI).
Taxon © 1995 International Association for Plant Taxonomy (IAPT)