Taxonomic and Phylogenetic Utility of Variation in Advertising Calls of Francolins and Spurfowls (Galliformes: Phasianidae)

Abstract

Systematists have not often made use of avian vocalizations to assess the taxonomic rank of birds, or to infer their phylogenetic relationships. The likely reasons for this stem from the perceived inability to distinguish genetic and ecological components of variation in vocalizations, the difficulty in detecting homology across taxa, as well as the diverse selection pressures acting on vocal characters which may make such characters particularly prone to convergent evolution. In this study, we scored and analysed DNA and vocal characters of two delineated assemblages of gamebirds, francolins and spurfowls. Our phylogenetic results suggest that short strophes evolved from longer strophes among taxa within the genera <i>Scleroptila</i> and <i>Peliperdix</i>. More generally, our results corroborate the francolin–spurfowl dichotomy, with francolin calls generally being long and tonal, containing a series of discrete elements that have detectable harmonics. In contrast, most spurfowls render short, atonal calls with elements that generally have no harmonics, although they may contain discrete elements. Phylogenetically, <i>Ortygornis sephaena</i> is placed with ‘true’ francolins and its closest relatives are the two phylogenetically enigmatic Asian francolins, the grey francolin, <i>Ortygornis pondicerianus</i>, and swamp francolin, <i>O. gularis</i>.