Quantifying the potential utility of phylogenetic characters

There has been a long history of interest in measuring the information conveyed by phylogenetic data. In one application, recent studies have attempted to compare the informativeness of morphological and molecular data, and of nucleotide and amino acid sequence alignments. While a variety of measures have been proposed to quantify phylogenetic information, most measures are rather unsatisfactory, failing to capture every aspect of the informativeness of a character. One measure, cladistic information content (CIC) is a natural measure of phylogenetic information. We show why CIC is preferable to other, recently introduced, measures, and, as an example, use CIC to compare the information of recent morphological and molecular datasets. This provides new empirical data relevant to the debate about the relative utility of morphology and molecules in phylogenetic inference, a subject of significant interest.