The phylogeny of francolins (Francolinus, Dendroperdix, Peliperdix and Scleroptila) and spurfowls (Pternistis) based on chick plumage (Galliformes: Phasianidae)

Abstract

Background: This paper describes the chick plumage of spurfowl (Pternistis) and francolin (Francolinus, Dendroperdix, Peliperdix and Scleroptila) chicks, tests its significance for phylogenetic relationships and also explores the patterns of character evolution in the francolin and spurfowl lineages. Previously regarded as monophyletic, the two evolutionarily distant clades are now divided into five genera. Questions considered were whether chick plumage supports the dichotomy between spurfowls and francolins and what role habitat matching plays. Methods: The study was based mainly on photographs of chick skins from the American Museum of Natural History and the Natural History Museum at Tring. Eight plumage characters were selected for comparative scoring, summarised in a matrix. These characters were subsequently analysed phylogenetically and their evolution was traced on the existing molecular phylogeny using a parsimony approach. Results: Based on chick plumage the phylogeny of species groups among francolins and spurfowls, was largely unresolved possibly ascribed to a high degree of symplesiomorphy inherent among the Phasianids. This possibly could have resulted in a high degree of polytomy particularly among the spurfowls and francolins. Furthermore, the ancestral state reconstructions revealed high prevalence of symplesiomorphic states and reversals which do not help in the classification of groups. Although the differences are described that separate some African francolins from spurfowls, other francolins (in Asia and Africa) share remarkably similar characteristics with spurfowls. Plain dark dorsal plumage is probably advantageous for avoiding detection by predators in forests, while facial stripes optimise the breaking of body shapes in dense grass cover (as in Scleroptila spp.) and semi-striped faces are advantageous for stationary camouflage under tree and bush cover (as in Pternistis spp.). Conclusions: Although symplesiomorphy is a hereditary explanation for downy colours and patterns, the traits relevant for habitat matching are combined in a manner which is determined (adaptation) by natural selection.