Morphometrics in the quantification of character state identity for the assessment of primary homology: an analysis of character variation of the genus Artibeus (Chiroptera : Phyllostomidae)

Abstract

The recognition of transformed homologues entails an evaluation of similarity of features among taxa and then an assessment of homology by character congruence. We approached the similarity test of character state identity with morphometric analyses of character variation to judge whether all variants from a taxonomic sample belong to the same phylogenetic state (taxic homology) or whether some variants are sufficiently different to recognize them as different states (transformational homology). This method seeks to recognize as many character states as the groups of taxon means that are revealed by an analysis of variance followed by a multiple range test. We exemplify this quantitative approach with an analysis of character variation for a phylogenetic study of eight Artibeus species and two outgroups. All 23 features analysed are taxonomically useful because at least two states could be defined. We argue that statistical tests are a consistent and non-arbitrary procedure for the similarity test in the assessment of character states when hypothesizing primary homologies. Cladistic analyses and descriptive indices of historical signals of previous molecular and morphological data, combined with our morphometric data, showed that morphometric characters contain cladistic structure and they are phylogeneticaly useful. (C) 2003 The Linnean Society of London.