Abstract
Starch gel electrophoresis was used to evaluate levels and patterns of genic differentiation among 10 species of galliform birds in the Phasianidae (9) and Tetraonidae (1). The phasianids included on Old World quail, a partridge, a pheasant, and six species of New World quail. Measures of within-species genetic variation included heterozygosity, percentage polymorphic loci, and number of alleles per polymorphic locus. These values were similar to but lower than those reported for other birds. Genetic distances among conspecific populations and among congeneric species were low compared to other avian results. Genetic distances among noncongeners both within and between families were considerably higher, however, than those reported for passerine birds. Thus, more studies of levels of genic differentiation among nonpasserines are required to complement the literature on genic divergence among passerines and to enable us to make general statements about genic evolution in birds.
Phenograms and phylogenetic trees suggested that Phasianus colchicus, Tympanuchus pallidicinctus, Coturnix coturnix, Alectoris chukar, and the New World quail (Odontophorinae) are genically distinct taxa. The branching sequence among the non-Odontophorine taxa is unresolved by our data. The branching order among taxa in the Odontophorinae from a common ancestor is: Cyrtonyx montezumae, Oreortyx pictus, Colinus virginianus, Callipepla squamata, Lophortyx gambelii, and L. californicus. The genera Cyrtonyx, Oreortyx, and Colinus are clearly distinct from Callipepla and Lophortyx, which are quite similar to each other genically.
We use a fossil species from the mid-Miocene of Nebraska to calibrate our genetic distances. We estimate dates of divergence of taxa in the Odontophorinae and offer a hypothesis on their historical biogeography. Our analysis suggests that three east-west range disjunctions could account for the origin of Oreortyx (12.6 MYBP), Colinus (7.0 MYBP), and Callipepla-Lophortyx (2.8 MYBP). We suggest that L. californicus and L. gambelii should be considered distinct species because of an apparent lack of panmixia in zones of sympatry, even though the D between them is typical of that found between subspecies of other birds. Oreortyx and Colinus should remain as distinct genera, while our data are equivocal on the status of Callipepla and Lophortyx.
Geographical, versus Sexual, Variation in Oreortyx pictus