A mitogenomic perspective on the ancient, rapid radiation in the Galliformes with an emphasis on the Phasianidae

Abstract

Background: The Galliformes is a well-known and widely distributed Order in Aves. The phylogenetic relationships of galliform birds, especially the turkeys, grouse, chickens, quails, and pheasants, have been studied intensively, likely because of their close association with humans. Despite extensive studies, convergent morphological evolution and rapid radiation have resulted in conflicting hypotheses of phylogenetic relationships. Many internal nodes have remained ambiguous.

Results: We analyzed the complete mitochondrial (mt) genomes from 34 galliform species, including 14 new mt genomes and 20 published mt genomes, and obtained a single, robust tree. Most of the internal branches were relatively short and the terminal branches long suggesting an ancient, rapid radiation. The Megapodiidae formed the sister group to all other galliforms, followed in sequence by the Cracidae, Odontophoridae and Numididae. The remaining clade included the Phasianidae, Tetraonidae and Meleagrididae. The genus Arborophila was the sister group of the remaining taxa followed by Polyplectron. This was followed by two major clades: ((((Gallus, Bambusicola) Francolinus) (Coturnix, Alectoris)) Pavo) and (((((((Chrysolophus, Phasianus) Lophura) Syrmaticus) Perdix) Pucrasia) (Meleagris, Bonasa)) ((Lophophorus, Tetraophasis) Tragopan))).

Conclusions: The traditional hypothesis of monophyletic lineages of pheasants, partridges, peafowls and tragopans was not supported in this study. Mitogenomic analyses recovered robust phylogenetic relationships and suggested that the Galliformes formed a model group for the study of morphological and behavioral evolution.

Figure 1

Phylogenetic hypotheses from various molecular, morphological and behavioral analyses of gamebirds. (a) The traditional classification from Johnsgard (1986); (b) morphological and behavioral data (Dyke et al., 2003); (c) combined data including two mitochondrial genes (CytB, ND2) and four nuclear introns (BFib7, DCoH3, OvoG, and Rhod1) (Kimball and Braun 2008); (d) insertion events of CR1 retrotransposable elements (Kaiser et al., 2007).

Figure 2

Phylogenetic tree based on the complete mitochondrial genomes of galliform birds. Bayesian posterior probabilities >70%, and maximum likelihood bootstrap proportions >50% are indicated on the branches. Species belonging to the Tribe Phasianini are marked in purple, and to Tribe Perdicini in green.

Figure 3

Results of partitioned Bremer support (PBS) analyses with respect to each node on the mitochondrial genome tree.