Chapter 6 - Phylogeny of the Pelecaniformes: Molecular Systematics of a Privative Group

Abstract

Phylogenetic hypotheses are the critical framework for understanding macroevolutionary patterns and interpreting comparative evolutionary data. Quantitative comparative analysis of the patterns in molecular, behavioral, and morphological evolution requires detailed phylogenies, particularly when character states and transformation series are incompletely known. For these reasons, a better understanding of higher order phylogenies is crucial when group monophyly is problematic and a major evolutionary change has occurred. Understanding the phylogenetic relationships of the pelecaniform birds, therefore, is central to the larger question of understanding the higher level relationships among nonpasserine birds. Critical assessment of the higher order relationships among nonpasserines is one of the most critical issues in avian systematics, and a crucial problem at present is whether the Pelecaniformes is monophyletic. Molecular studies suggest that Pelecaniformes is not monophyletic and the former members are instead grouped with other early branching groups. If these molecular-based studies are validated and Pelecaniformes is dismantled, then the traditional morphological framework that forms the basis for most phylogenetic assumptions in avian systematics is clearly in need of re-examination, as it pertains to modern systematics research.