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 a ttempts to reconstruct gull relationships have met with little success . In the present study I use 117 characters from the skeleton and 64 f rom 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 evid ence, I found that incongruence between the osteological and integumen tary character sets accounts for only a minority of the total incongru ence 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 fo r determining higher-level structure, whereas integumentary evidence i s important for resolving lower-level relationships within the gull gr oup. Finally, I found that integumentary characters are not dramatical ly more homoplasious than osteological characters, and argue that casu al dismissal of integumentary characters as ''too labile'' is unwarran ted. (C) 1998 The Willi Hennig Society.