REGULAR A RTI CLE Congruence of Morphological and Molecular Phylogenies

When phylogenetic trees constructed from morphological and molecular evidence disagree (i.e. are incongruent) it has been suggested that the differences are spurious or that the molecular results should be preferred a priori. Comparing trees can increase confidence (congruence), or demonstrate that at least one tree is incorrect (incongruence). Statistical analyses of 181 molecular and 49 morphological trees shows that incongruence is greater between than within the morphological and molecular partitions, and this difference is significant for the molecular partition. Because the level of incongruence between a pair of trees gives a minimum bound on how much error is present in the two trees, our results indicate that the level of error may be underestimated by congruence within partitions. Thus comparisons between morphological and molecular trees are particularly useful for detecting this incongruence (spurious or otherwise). Molecular trees have higher average congruence than morphological trees, but the difference is not significant, and both withinand between-partition incongruence is much lower than expected by chance alone. Our results suggest that both molecular and morphological trees are, in general, useful approximations of a common underlying phylogeny and thus, when molecules and morphology clash, molecular phylogenies should not be considered more reliable a priori. D. Pisani (&) Laboratory of Evolutionary Biology, Department of Biology, The National University of Ireland, Maynooth, Co. Kildare, Ireland e-mail: [email protected] D. Pisani M. Wilkinson Department of Zoology, The Natural History Museum, London SW7 5BD, UK D. Pisani M. J. Benton Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK 123 Acta Biotheor (2007) 55:269–281 DOI 10.1007/s10441-007-9015-8