The influence of character correlations on phylogenetic analyses: a case study of the carnivoran cranium

Abstract

Character independence is a major assumption in many morphology-based phylogenetic analyses (Felsenstein, 1973; Emerson and Hastings, 1998). However, the fact that most studies of modularity and morphological integration have found significant correlations among many phenotypic traits worryingly calls into question the validity of this assumption. Because gathering data on character correlations for every character in every taxon of interest is unrealistic, studies of modularity are more tractable for assessing the impact of character non-independence on phylogenetic analyses in a real system because modules summarise broad patterns of trait correlations. In this study, we use empirically derived data on cranial modularity and morphological integration in the carnivoran skull to assess the impact of trait correlations on phylogenetic analyses of Carnivora.