Biological Journal of the Linnean Society, Vol. 73, pp. 187-198
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A molecular phylogeny of the peacock-pheasants (Galliformes, Polyplectron spp.) indicates loss and reduction of ornamental traits and display behaviours
Rebecca T. Kimball*,
Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA (R.T.K., E.L.B., J.D.L); Departments of Evolution, Ecology and Organismal Biology (R.T.K.) and Plant Biology (E.L.B.), Ohio State University, Columbus, OH, 43210, USA; Istituto Nazionale per la Fauna Selvatica, via Cà Fornacetta 9, 40064, Ozzano dell Emilia, (BO), Italy (V.L., E.R.);
E.L.B. and R.T.K. are currently in the Department of Zoology at the University of Florida.
The South-east 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 sizes and distribution of ocelli vary among species. All Polyplectron species have lateral displays, but species with ocelli also display frontally to females, with feathers held erect and spread to clearly display the ocelli. The two least ornamented Polyplectron species, one of which completely lacks ocelli, have been considered the primitive members of the genus, implying that ocelli are derived. 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 in fact 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 less-ornamented species inhabit montane regions, while the ornamented species inhabit lowland regions. The implications of these findings are discussed in light of models of sexual selection. The phylogeny is not congruent with current geographical 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 .
E.R. and V.L. were supported by the Italian Institute of Wildlife Biology (INFS). Some DNA sequencing was performed in the NSF supported (RIMI programme grant HRD-9550649) Molecular Biology Facility at the University of New Mexico.
* Corresponding author