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Introduction
Phasianidae represent the most species-rich and morphologically diverse radiation of Galliformes (landfowl or gamebirds) (del Hoyo et al., 1994). This family includes pheasants, Old World quails, partridges, peafowl, grouse, and turkeys. North America is inhabited today by two native phasianid clades—the Meleagridinae (turkeys) and the Tetraoninae (grouse). Several other phasianid species, including Phasianus colchicus Linnaeus, 1758 (common pheasant) and Alectoris chukar Gray, 1830 (chukar) have been introduced by humans in historical times and established breeding populations. Aside from Phasianidae, two other families of Galliformes also occur in North America today: the Odontophoridae (New World quail) and Cracidae (chachalacas, guans, and curassows).
Meleagridinae are distinctive birds that are easily identified by their large size, bare heads, and iridescent plumage. Today the clade is represented by just two species, Meleagris gallopavo Linnaeus, 1758 (wild turkey) and Meleagris ocellata Cuvier, 1820 (ocellated turkey) (placed in the separate genus Agriocharis in some earlier taxonomies). Tetraoninae are widespread throughout the Holarctic and represented by 19 extant species, 12 of which occur in North America (Gill et al., 2021). These species range in size from the small ptarmigans to the impressive capercaillies, and share various adaptations to cold winter conditions, including feathered nostrils and feathered and/or pectinate toes that aid in traveling atop snow.
The phylogenetic relationships of Meleagridinae and Tetraoninae have been the subject of substantial debate. Some early taxonomies depicted turkeys and grouse as successive branches on the galliform tree (e.g., Johnsgard, 1986), whereas others placed them in their own families separate from Phasianidae (Meleagrididae and Tetraonidae; e.g., de Juana, 1994; Porter, 1994). Somewhat surprisingly, previous phylogenetic analyses based on morphological data failed to support a sister-group relationship between these two rather similar groups of birds (Dyke et al., 2003; Ksepka, 2009). Early molecular analyses based on DNA hybridization (Sibley and Alhquist, 1990) and mitochondrial DNA supported a sister-group relationship between grouse and turkeys (Kimball et al., 1999; Dimcheff et al., 2002), but subsequent studies based on larger sequence samples recovered alternate topologies (Crowe et al., 2006; Kan et al., 2010). Most recently, molecular phylogenetic analyses have converged on a topology supporting a sister-group relationship between Meleagridinae and Tetraoninae, suggesting they shared a relatively recent common ancestor, and possibly split from one another following a dispersal event into...