Feeding behavior, toe count, and the phylogenetic relationships among alcedinine kingfishers (Alcedininae)

摘要

The pygmy kingfishers of the Old World tropics (Alcedininae) display a range of feeding behaviors, plumage types, and morphologies that have caused much taxonomic confusion in the group. We sequenced mitochondrial and nuclear genes to reconstruct a phylogenetic hypothesis for the subfamily, which was then used to examine the utility of common taxonomic characters. The phylogenetic hypothesis reveals multiple shifts between insectivory and piscivory, as well as homoplasy in bill color and plumage color. Piscivores and insectivores are interspersed across the tree, as are blue and rufous plumage types. It is apparent that reliance on these characters to delineate genera has resulted in classifications that do not describe natural groups. The sole taxonomic character examined that defines a natural division in the subfamily, toe count, is also the one generally dismissed as non-informative in the alcedinines, yet all species with a reduction in the number of toes form a clade. It is recommended that four genera be retained to describe the variation within pygmy kingfishers.