PROPORTIONAL CHANGE AND PATTERNS OF HOMOPLASY - SANDERSON AND DONOGHUE REVISITED

The effects of two parameters, (1) the number of taxa and (2) the perc entage of characters that change per node (referred to as the amount o f proportional change or APC) on the retention index (RI) and the cons istency index (CI) were examined. Random data sets were generated with a variety of different combinations of the number of taxa and the APC ; five replicates for each unique combination were generated producing a total of 660 data sets. Results suggest that both the number of tax a and the APC are significantly correlated with the CI. In data sets w ith more than seven taxa, the APC explains more variation in homoplasy than does the number of taxa. The RI was found to be very strongly co rrelated with the APC and only weakly correlated with the number of ta xa. (C) 1997 The Willi Hennig Society.