THE UTILITY OF DNA-SEQUENCES OF AN INTRON FROM THE BETA-FIBRINOGEN GENE IN PHYLOGENETIC ANALYSIS OF WOODPECKERS (AVES, PICIDAE)

Estimating phylogenies from DNA sequence data has become the major met hodology of molecular phylogenetics. To date, molecular phylogenetics of the vertebrates has been very dependent on mtDNA, but studies invol ving mtDNA are limited because the several genes comprising the mt-gen ome are inherited as a single linkage group. The only apparent solutio n to this problem is to sequence additional genes, each representing a distinct linkage group, so that the resultant gene trees provide inde pendent estimates of the species tree. There exists the need to find n ovel gene sequences which contain enough phylogenetic information to r esolve relationships between closely related species. A possible sourc e is the nuclear-encoded introns, because they evolve more rapidly tha n exons. We designed primers to amplify and sequence the 7 intron from the beta-fibrinogen gene for a recently evolved group, the woodpecker s. We sequenced the entire intron for 10 specimens representing five s pecies. Nucleotide substitutions are randomly distributed along the le ngth of the intron, suggesting selective neutrality. A preliminary ana lysis indicates that the phylogenetic signal in the intron is as stron g as that in the mitochondrial encoded cytochrome b (cyt b) gene. The topology of the beta-fibrinogen tree is identical to that of the cyt b tree. This analysis demonstrates the ability of the 7 intron of beta- fibrinogen to provide well resolved, independent gene trees for recent ly evolved groups and establishes it as a source of sequences to be us ed in other phylogenetic studies. (C) 1997 Academic Press.