title: Mitochondrial genomes from major lizard families suggest their phylogenetic relationships and ancient radiations.
abstract: In placental mammals and birds, molecular data generally support a view that they diverged into their ordinal groups in good response to mid-Cretaceous continental fragmentations. However, such divergence patterns have rarely been studied for reptiles for which phylogenetic relationships among their major groups have not yet been established molecularly. Here, I determined complete or nearly complete mitochondrial DNA sequences from seven lizard families and reconstructed phylogenetic relationships between major lizard families. When snakes were included, maximum likelihood analysis did not support a morphological view of the snakes-varanoids affinity, although several other competing hypotheses on the position of snakes still cannot be discriminated presumably due to extremely long branches of the snake lineages. I also conducted clock-free Bayesian analyses to show that divergence times between major lizard families were centered in Triassic-Jurassic times. Thus, lizards include much deeper divergences than the mammals and birds and they appear to have already radiated into various families prior to the mid-Cretaceous major continental fragmentation.
authors.affiliation: Division of Material Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan. h44858a@nucc.cc.nagoya-u.ac.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kumazawa
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D049810:Genetic Speciation; D014644:Genetic Variation; D008116:Lizards / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013997:Time Factors
chemical_list: D004272:DNA, Mitochondrial