title: Higher-level snake phylogeny inferred from mitochondrial DNA sequences of 12S rRNA and 16S rRNA genes.
abstract: Portions of two mitochondrial genes (12S and 16S ribosomal RNA) were sequenced to determine the phylogenetic relationships among the major clades of snakes. Thirty-six species, representing nearly all extant families, were examined and compared with sequences of a tuatara and three families of lizards. Snakes were found to constitute a monophyletic group (confidence probability [CP] = 96%), with the scolecophidians (blind snakes) as the most basal lineages (CP = 99%). This finding supports the hypothesis that snakes underwent a subterranean period early in their evolution. Caenophidians (advanced snakes), excluding Acrochordus, were found to be monophyletic (CP = 99%). Among the caenophidians, viperids were monophyletic (CP = 98%) and formed the sister group to the elapids plus colubrids (CP = 94%). Within the viperids, two monophyletic groups were identified: true vipers (CP = 98%) and pit vipers plus Azemiops (CP = 99%). The elapids plus Atractaspis formed a monophyletic clade (CP = 99%). Within the paraphyletic Colubridae, the largely Holarctic Colubrinae was found to be a monophyletic assemblage (CP = 98%), and the Xenodontinae was found to be polyphyletic (CP = 91%). Monophyly of the henophidians (primitive snakes) was neither supported nor rejected because of the weak resolution of relationships among those taxa, except for the clustering of Calabaria with a uropeltid, Rhinophis (CP = 94%).
authors.affiliation: Department of Biology, Pennsylvania State University.
authors.forename: P J
authors.initials: PJ
authors.lastname: Heise
authors.forename: L R
authors.initials: LR
authors.lastname: Maxson
authors.forename: H G
authors.initials: HG
authors.lastname: Dowling
authors.forename: S B
authors.initials: SB
authors.lastname: Hedges
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012911:Snakes / Q000145:classification* / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C075526:RNA, ribosomal, 12S