Do cladistic and morphometric data capture common patterns of morphological disparity?

The distinctly non-random diversity of organis- mal form manifests itself in discrete clusters of taxa that share a common body plan. As a result, analyses of disparity require a scalable comparative framework. The difficulties of applying geometric morphometrics to disparity analyses of groups with vastly divergent body plans are overcome partly by the use of cladistic characters. Character-based disparity analyses have become increasingly popular, but it is not clear how they are affected by character coding strategies or revi- sions of primary homology statements. Indeed, whether cla- distic and morphometric data capture similar patterns of morphological variation remains a moot point. To address this issue, we employ both cladistic and geometric morpho- metric data in an exploratory study of disparity focussing on caecilian amphibians. Our results show no impact on relative intertaxon distances when different coding strategies for cla- distic characters were used or when revised concepts of homology were considered. In all instances, we found no sta- tistically significant difference between pairwise Euclidean and Procrustes distances, although the strength of the corre- lation among distance matrices varied. This suggests that cla- distic and geometric morphometric data appear to summarize morphological variation in comparable ways. Our results support the use of cladistic data for characteriz- ing organismal disparity.