A priori estimation of phylogenetic information conserved in aligned sequences.

A new phenomenological approach to explorative data analysis, the estimation of spectra of supporting positions, allows the search for conserved tracks left by phylogeny in DNA sequences. Spectra of supporting positions can be generated without reference to a tree topology or a model of sequence evolution and are therefore an ideal tool for a priori estimation of information content of data sets. Analysis of published 18S rDNA alignments shows that signal to noise relationship varies greatly in a way not detected by conventional tree-construction methods.