title: Sister group relationship of turtles to the bird-crocodilian clade revealed by nuclear DNA-coded proteins.
abstract: The phylogenetic position of turtles is a currently controversial issue. Recent molecular studies rejected a traditional view that turtles are basal living reptiles (Hedges, S. B., and L. L. Poling. 1999. A molecular phylogeny. Science 83:998-1001; Kumazawa, Y., and M. Nishida. 1999. Complete mitochondrial DNA sequences of the green turtle and blue-tailed mole skink, statistical evidence for archosaurian affinity of turtles. Mol. Biol. Evol. 16:784-792). Instead, these studies grouped turtles with birds and crocodiles. The relationship among turtles, birds, and crocodiles remained unclear to date. To resolve this issue, we have cloned and sequenced two nuclear genes encoding the catalytic subunit of DNA polymerase alpha and glycinamide ribonucleotide synthetase-aminoimidazole ribonucleotide synthetase-glycinamide ribonucleotide formyltransferase from amniotes and an amphibian. The amino acid sequences of these proteins were subjected to a phylogenetic analysis based on the maximum likelihood method. The resulting tree showed that turtles are the sister group to a monophyletic cluster of archosaurs (birds and crocodiles). All other possible tree topologies were significantly rejected.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Iwabe
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Hara
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kumazawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Shibamoto
authors.forename: Yumi
authors.initials: Y
authors.lastname: Saito
authors.forename: Takashi
authors.initials: T
authors.lastname: Miyata
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Katoh
mesh_terms: D000489:Alligators and Crocodiles / Q000235:genetics*; D000818:Animals; D001717:Birds / Q000235:genetics*; D002467:Cell Nucleus / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D013045:Species Specificity; D014426:Turtles / Q000235:genetics*
chemical_list: D011506:Proteins; D004247:DNA