title: Live birth among Iguanian lizards predates Pliocene--Pleistocene glaciations.
abstract: Among tetrapods, viviparity is estimated to have evolved independently within Squamata (lizards and snakes) more than 100 times, most frequently in species occupying cold climate environments. Because of this relationship with cold climates, it is sometimes assumed that many origins of squamate viviparity occurred over the past 2.5-4 Myr during the Pliocene-Pleistocene glaciations; however, this hypothesis is untested. Divergence-dating analysis on a 733-species tree of Iguanian lizards recovers 20 independent lineages that have evolved viviparity, of which 13 multispecies groups derived live birth prior to glacial advances (8-66 Myr ago). These results place the transitions from egg-laying to live birth among squamates in a well-supported historical context to facilitate examination of the underlying phenotypic and genetic changes associated with this complex shift in reproduction.
authors.affiliation: Department of Biology, Clarkson University, 8 Clarkson Avenue, MRC 5805, Potsdam, NY 13699-5805, USA. jschulte@clarkson.edu
authors.forename: James A
authors.initials: JA
authors.lastname: Schulte
authors.forename: Franck
authors.initials: F
authors.lastname: Moreno-Roark
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D005260:Female; D007076:Iguanas / Q000502:physiology*; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D052286:Viviparity, Nonmammalian / Q000502:physiology*
chemical_list: D017931:DNA Primers