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 dat a were used in combined or simultaneous analyses. Assessment of the di sagreement between these data sources, as measured by the incongruence length difference, reveals substantial conflict for the studies surve yed. In addition, the partitioned Bremer support was used to measure t he degree of support provided by each data partition when analyzed tog ether. Despite the significant incongruence found for nearly half the studies, the PBS indices suggest both types of data contribute positiv ely 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 res ult, combined with the fact that morphological characters generally ex hibit higher consistency, indicates that this source of character info rmation continues to be useful in systematics studies despite the incr easing volume of available molecular data. (C) 1998 Academic Press.