Comparison of similarity coefficients based on RAPD markers in the common bean

The alterations caused by eight different similarity coefficients were eval uated in the clustering and ordination of 27 common bean (Phaseolus vulgari s L.) cultivars analyzed by RAPD markers. The Anderberg, simple matching, R ogers and Tanimoto, Russel and Rao, Ochiai, Jaccard, Sorensen-Dice, and Och iai Il's coefficients were tested. Comparisons among the coefficients were made through correlation analysis of genetic distances obtained by the comp lement of these coefficients, dendrogram evaluation (visual inspection and consensus fork index - CIC), projection efficiency in a two-dimensional spa ce, and groups formed by Tocher's optimization procedure. The employment of different similarity coefficients caused few alterations in cultivar class ification, since correlations among genetic distances were larger than 0.86 . Nevertheless, the different similarity coefficients altered the projectio n efficiency in a two dimensional space and formed different numbers of gro ups by Tocher's optimization procedure. Among these coefficients, Russel an d Rao's was the most discordant and the Sorensen-Dice was considered the mo st adequate due to a higher projection efficiency in a two-dimensional spac e. Even though few structural changes were suggested in the most different groups, these coefficients altered some relationships between cultivars wit h high genetic similarity.