Assessing the relative contribution of molecular and morphological characters in simultaneous analysis trees.

We examined the contribution of morphological and molecular character information for 15 systematics studies in which these two kinds of data were used in combined or simultaneous analyses. Assessment of the disagreement between these data sources, as measured by the incongruence length difference, reveals substantial conflict for the studies surveyed. In addition, the partitioned Bremer support was used to measure the degree of support provided by each data partition when analyzed together. Despite the significant incongruence found for nearly half the studies, the PBS indices suggest both types of data contribute positively to the combined analyses and that, when standardized by the number of phylogenetically informative characters, morphology data generally provide equal or greater support than do the molecular data. This result, combined with the fact that morphological characters generally exhibit higher consistency, indicates that this source of character information continues to be useful in systematics studies despite the increasing volume of available molecular data. Copyright 1998 Academic Press.