AVIAN MOLECULAR SYSTEMATICS, 1970S TO 1990S

We assessed the current state of avian molecular systematics by (i) co nsidering some of the historical factors that have shaped the field in the last 20 years, (ii) reviewing the most commonly used molecular me thods, and (iii) comparing higher-level phylogenies via congruence ana lysis. This three-pronged approach permitted us to identify strongly s upported aspects of avian phylogeny and to propose technological and m ethodological explanations when congruence was low. We found, in gener al, that few areas of higher-level avian phylogeny are well supported and, hence, well understood. One main reason for this is that, despite a great deal of effort, few studies of higher-level avian phylogeneti c relationships have been well planned and executed. Some investigatio ns, for example, have gone astray because of preconceptions about rate s of molecular evolution and monophyly, and others suffer from such pr oblems as failure to find the shortest tree, lack of an outgroup, use of a nonmetric distance measure, and simple mistakes. This is not to s ay, however, that available techniques are incapable of reconstructing avian phylogeny. The extent of congruence that we found among branchi ng patterns estimated by different methods, including carefully design ed cladistic morphological analyses, indicates that when applied appro priately, a variety of methods provide useful insight into phylogeny.