Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion

Abstract

In recent years, avian systematics has been characterized by a diminished reliance on morphological cladistics of modern taxa, intensive palaeornithogical research stimulated by new discoveries and an inundation by analyses based on DNA sequences. Unfortunately, in contrast to significant insights into basal origins, the broad picture of neornithine phylogeny remains largely unresolved. Morphological studies have emphasized characters of use in palaeontological contexts. Molecular studies, following disillusionment with the pioneering, but non-cladistic, work of Sibley and Ahlquist, have differed markedly from each other and from morphological works in both methods and findings. Consequently, at the turn of the millennium, points of robust agreement among schools concerning higher-order neornithine phylogeny have been limited to the two basalmost and several mid-level, primary groups. This paper describes a phylogenetic (cladistic) analysis of 150 taxa of Neornithes, including exemplars from all non-passeriform families, and subordinal representatives of Passeriformes. Thirty-five outgroup taxa encompassing Crocodylia, predominately theropod Dinosauria, and selected Mesozoic birds were used to root the trees. Based on study of specimens and the literature, 2954 morphological characters were defined; these characters have been described in a companion work, approximately one-third of which were multistate (i.e. comprised at least three states), and states within more than one-half of these multistate characters were ordered for analysis. Complete heuristic searches using 10 000 random-addition replicates recovered a total solution set of 97 well-resolved, most-parsimonious trees (MPTs). The set of MPTs was confirmed by an expanded heuristic search based on 10 000 random-addition replicates and a full ratchet-augmented exploration to ascertain global optima. A strict consensus tree of MPTs included only six trichotomies, i.e. nodes differing topologically among MPTs. Bootstrapping (based on 10 000 replicates) percentages and ratchet-minimized support (Bremer) indices indicated most nodes to be robust. Several fossil Neornithes (e.g. Dinornithiformes, Aepyornithiformes) were placed within the ingroup a posteriori either through unconstrained, heursitic searches based on the complete matrix augmented by these taxa separately or using backbone-constraints. Analysis confirmed the topology among outgroup Theropoda and achieved robust resolution at virtually all levels of the Neornithes. Findings included monophyly of the palaeognathous birds, comprising the sister taxa Tinamiformes and ratites, respectively, and the Anseriformes and Galliformes as monophyletic sister-groups, together forming the sister-group to other Neornithes exclusive of the Palaeognathae (Neoaves). Noteworthy inferences include: (i) the sister-group to remaining Neoaves comprises a diversity of marine and wading birds; (ii) Podicipedidae are the sister-group of Gaviidae, and not closely related to the Phoenicopteridae, as recently suggested; (iii) t...

Comparative digesta retention patterns in ratites

“…For mammals, detailed morphological soft tissue analyses, such as lung anatomy (Wallau et al 2000) or anatomy of the gastrointestinal tract (Langer 2001), can be used to derive phylogenies, but we are not aware of cases where such characteristics have been used to actually resolve a phylogenetic debate. For birds, characteristics of the gastrointestinal tract have been included in a large-scale morphology-based phylogeny reconstruction (Livezey and Zusi 2007) but represented only~0.5% (16 of 2945) of the characters used (Livezey and Zusi 2006). When compared to the 2 speciation models presented by Mitchell et al (2014), which are based on continental vicariance (i.e.…”

Hummingbirds have a greatly enlarged hippocampal formation

“…We also examined the brains of two window-killed common swifts (Apus apus) that were immersion-fixed in 4 per cent paraformaldehyde and sent to us by Dr Gerard Gory (Museum d'Histoire Naturelle de Nimes, France). Swifts (Apodidae) are the sister group to hummingbirds [9,10] and examining even one species will provide some insight into determining whether any changes in HF arose solely in hummingbirds or are common to all members of the clade (Apodiformes).…”

Group-foraging is not associated with longevity in North American birds

“…A phylogenetic analysis relied on independent contrasts, which were calculated using the PDAP module (Midford et al 2008) within MESQUITE (Maddison & Maddison 2009) assigning all branch lengths to 1. The phylogeny underlying the calculations was based mostly on two recent papers describing phylogenetic relationships among bird families (Jønsson & Fjeldså 2006;Livezey & Zusi 2007). In addition, I used several papers describing interspecies relationships within various bird families (appendix B in the electronic supplementary material).…”