The systematic position of the avian species Rhodinocichla rosea is unclear. Recent opinions are that it is either a mockingbird (family Mimidae) or a tanager (Thraupinae; Emberizidae). In either case, it would be an atypical member of the family. We sequenced approximately 600 bases of the mitochondrial cytochrome oxidase I (COI) gene of Rhodinocichla, several mimids, tanagers, and other passerines. We used maximum likelihood (ML), distance and parsimony approaches to analyze the sequences and concluded that Rhodinocichla belongs to the family Emberizidae. Phenotypic characteristics that suggested its relationship with mimids are the product of convergent evolution. The precise relationships of Rhodinocichla within the Emberizidae could not be resolved. Short internal branches in ML and distance trees suggested, as did earlier genetic studies, that the radiation of that family was explosive. Apparently, the extent of the tanagers as a higher taxon needs to be clarified. Our analysis of the evolutionary dynamics of avian COI suggested that its usefulness for phylogenetic studies is limited because silent positions saturate rapidly and replacement substitutions are rare. Thus, our data indicate that COI nucleotide data will be most useful in intraspecific investigations, while other data suggested its usefulness at the interordinal level.
Copyright 1997 Academic Press