An unresolved issue in higher avian systematics is the position of the fowl-like and the duck-like birds, Galliformes and Anseriformes, respectively. Most studies place these orders at the base of the neognath radiation. While DNA hybridization data support a sister-group relationship of Galliformes and Anseriformes, macromolecular sequence analyses have not yet been able to provide a clear-cut answer. In this study, we present nucleotide sequences coding for the eye lens proteins aA-and aB-crystallin of a palaeognath, a galliform, an anseriform, and two other neognathous birds. Phylogenetic analyses of this data set clearly support a galliform/anseriform clade, to the exclusion of other neognaths. r 1997 Academic Pres
