Biological Journal of the Linnean Society, Vol. 73, pp. 187-198
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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 .
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