Mitochondrial resolution of a deep branch in the genealogical tree for perching birds.
Animal mitochondrial DNA (mtDNA) is known to contain information about the genealogical relations among closely related species and is shown here to yield information about distant relations as well. Our results also draw attention to the need for caution in using third positions of codons for tree construction. This is evident from comparative studies of the cytochrome b gene in 13 species representing major groups within the order of perching birds (Passeriformes). Sequences of a 924 base-pair segment of this gene were obtained from each of these species via the polymerase chain reaction and a novel set of versatile primers. With a woodpecker sequence as an outgroup, trees that separate songbirds from other perching birds and resolve the ancient branch leading to songbirds were obtained utilizing the conservative first and second positions of codons. Analysis of positions within codons suggests that, for deep branches, the skewed base composition at the fast-changing third positions can result in phylogenetic disinformation, which conflicts with the information retained in the first and second positions. The mitochondrial tree shows broad concordance with that based on hybridization of nuclear DNA; however, parsimony and maximum likelihood methods suggest a close kinship between thrushes and Australian babblers, in agreement with the traditional morphological classification.
Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
S V
SV
Edwards
P
P
Arctander
A C
AC
Wilson
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D001717:Birds / Q000235:genetics*; D003062:Codon / Q000235:genetics; D003573:Cytochrome b Group / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012689:Sequence Homology, Nucleic Acid
D003062:Codon; D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D015345:Oligonucleotide Probes