TESTING THE PHYLOGENY OF SWORDTAIL FISHES USING SPLIT DECOMPOSITION AND SPECTRAL-ANALYSIS

We examine ways of testing for the reliability of inference from biolo gical sequence data using sequences from Xiphophorus fishes and newly implemented methodology for sequence analysis. The approach we take pr ovides one means to examine the fit between model and data for differe nt sequences and hence to evaluate heterogeneity between data sets. In the case of the present study we show D-loop sequences to be a better molecule for studying the phylogeny of Xiphophorus fishes than cytoch rome b sequences. The results of the split decomposition and spectral analysis confirm an earlier phylogenetic hypothesis which had been bas ed on maximum parsimony, neighbor-joining, maximum likelihood analyses .