A phylogeny of the gulls (Aves: Larinae) inferred from osteological and integumentary characters

Gulls (Aves: Larinae) are among the best-studied of birds, yet prior attempts to reconstruct gull relationships have met with little success. In the present study I use 117 characters from the skeleton and 64 from the integument to test gull monophyly and estimate gull phylogeny. One shortest tree, requiring 9747 unweighted changes and having a CI of 0.267, was obtained; on this tree the genus Larus is polyphyletic. Although the tree is fully resolved, support for many of the inferred clades is poor. In a comparison of osteological and integumentary evidence, I found that incongruence between the osteological and integumentary character sets accounts for only a minority of the total incongruence observed, and suggest that low between-set incongruence may be a consequence of the low signal-to-noise ratio in each set of characters. I also found that osteological evidence is particularly important for determining higher-level structure, whereas integumentary evidence is important for resolving lower-level relationships within the gull group. Finally, I found that integumentary characters are not dramatically more homoplasious than osteological characters, and argue that casual dismissal of integumentary characters as "too labile" is unwarranted. (C) 1998 The Willi Hennig Society.