A Parsimonay Analysis of Eukaryotic Small Subunit Ribosomal Rna ("18 S") Sequences

Using the principles of Felsenstein's DNA parsimony analysis program (package PHYLIP 3.2), a program with the capacity to handle data sets of the magnitude of ss rRNA has been developed. With this program we applied an heuristic approach to 83 s rRNA sequences from the Antwerp data bank, compared along 4230 positions of their alignment. Branch and bound can also be applied to a smaller number of sequences. We suggest a heuristic tree for a large number of species might be more interesting than a proven minimal tree for a smaller set of species. Comparisons are also made with earlier studies using distance matrix methods; caution is urged for deciding on the evolutionary position of widely divergent groups, whatever the tree building technique used.