Kimball, R.T., E.L. Braun, J.D. Ligon, E. Randi, and V. Lucchini. 2001. A Molecular Phylogeny of the Peacock-pheasants (Galliformes: Polyplectron spp.) Indicates Loss and Reduction of Ornamental Traits and Display Behaviors. Biological Journal of the Linnean Society 73: 187-198.

The Southeast Asian pheasant genus Polyplectron is comprised of six or seven species which are characterized by ocelli (ornamental eye-spots) in all but one species, though the size and distribution of ocelli vary among species. All Polyplectron species have lateral displays, but those species with ocelli also display frontally to females, with feathers spread and erect to clearly display the ocelli on the tail, wing, and mantle. The two least ornamented Polyplectron species, one of which completely lacks ocelli, have been considered to be the primitive members of the genus, implying that ocelli are a derived trait. We examined this hypothesis phylogenetically using complete mitochondrial cytochrome b and control region sequences, as well as sequences from intron G in the nuclear ovomucoid gene, and found that the two least ornamented species are actually the most recently evolved. Thus, the absence and reduction of ocelli and other ornamental traits in Polyplectron are recent losses. The only variable that may correlate with the reduction in ornamentation is habitat, as the two species with reduced ornamentation are montane species, while the ornamented species are lowland. The implications of these finding are discussed in light of models of sexual selection. The phylogeny is not congruent with current geographic distributions, and there is little evidence that Pleistocene sea level changes promoted speciation in this genus. Maximum likelihood and maximum parsimony analyses of cytochrome b sequences suggest that the closest relatives of Polyplectron are probably the peafowl and the argus pheasants.