Assessing Phylogenetic Relationships among Galliformes: A Multigene Phylogeny with Expanded Taxon Sampling in Phasianidae

Galliform birds (relatives of the chicken and turkey) have attracted substantial attention due to their importance to society and value as model systems. This makes understanding the evolutionary history of Galliformes, especially the species-rich family Phasianidae, particularly interesting and important for comparative studies in this group. Previous studies have differed in their conclusions regarding galliform phylogeny. Some of these studies have suggested that specific clades within this order underwent rapid radiations, potentially leading to the observed difficulty in resolving their phylogenetic relationships. Here we presented analyses of six nuclear intron sequences and two mitochondrial regions, an amount of sequence data larger than many previous studies, and expanded taxon sampling by collecting data from 88 galliform species and four anseriform outgroups. Our results corroborated recent studies describing relationships among the major families, and provided further evidence that the traditional division of the largest family, the Phasianidae into two major groups ("pheasants" and "partridges") is not valid. Within the Phasianidae, relationships among many genera have varied among studies and there has been little consensus for the placement of many taxa. Using this large dataset, with substantial sampling within the Phasianidae, we obtained strong bootstrap support to confirm some previously hypothesized relationships and we were able to exclude others. In addition, we added the first nuclear sequence data for the partridge and quail genera Ammoperdix, Caloperdix, Excalfactoria, and Margaroperdix, placing these taxa in the galliform tree of life with confidence. Despite the novel insights obtained by combining increased sampling of taxa and loci, our results suggest that additional data collection will be necessary to solve the remaining uncertainties.