Computational problems in molecular systematics.

The development of extremely powerful computer programs and the ready availability of microcomputers has revealed several computational problems with data analysis. These problems occur in the handling of systematic data in general and molecular systematic data in particular. This paper examines three areas of controversy in molecular systematics resulting from increased computer power. We start by examining the first step in DNA sequence analysis, the establishment of homology via sequence alignment. Next we examine several problems in phylogenetic analysis that have arisen in the last few years due to use of the PAUP (Swofford, 1991), HENNIG86 (Farris, 1988), and PHYLIP programs. These problems include limitations on the number of taxa examined in a given analysis and the accuracy of the parsimony trees in such analyses. The final subject is an examination of programs used for assessing tree robustness. We concentrate on certain programs (such as MALIGN (Wheeler and Gladstein, 1993), PAUP (Swofford, 1991), HENNIG86 (Farris, 1988), PHYLIP (Felsenstein, 1990), CLADOS (Nixon, 1993), MacClade (Maddison and Maddison, 1993), etc.), but similar comments about other programs could also be made.