title: Diversification in the Mexican horned lizard Phrynosoma orbiculare across a dynamic landscape.
abstract: The widespread montane Mexican horned lizard Phrynosoma orbiculare (Squamata: Phrynosomatidae) represents an ideal species to investigate the relative impacts of Neogene vicariance and Quaternary climate change on lineage diversification across the Mexican highlands. We used mitochondrial DNA to examine the maternal history of P. orbiculare and estimate the timing and tempo of lineage diversification. Based on our results, we inferred 11 geographically structured, well supported mitochondrial lineages within this species, suggesting P. orbiculare represents a species complex. Six divergences between lineages likely occurred during the Late Miocene and Pliocene, and four splits probably happened during the Pleistocene. Diversification rate appeared relatively constant through time. Spatial and temporal divergences between lineages of P. orbiculare and co-distributed taxa suggest that a distinct period of uplifting of the Transvolcanic Belt around 7.5-3 million years ago broadly impacted diversification in taxa associated with this mountain range. To the north, several river drainages acting as filter barriers differentially subdivided co-distributed highland taxa through time. Diversification patterns observed in P. orbiculare provide additional insight into the mechanisms that impacted differentiation of highland taxa across the complex Mexican highlands.
authors.affiliation: School of Life Sciences, University of Nevada, Las Vegas, NV 89154-4004, USA. brysonjr@unlv.nevada.edu
authors.forename: Robert W
authors.initials: RW
authors.lastname: Bryson
authors.forename: Uri Omar
authors.initials: UO
authors.lastname: García-Vázquez
authors.forename: Brett R
authors.initials: BR
authors.lastname: Riddle
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D001499:Bayes Theorem; D019143:Evolution, Molecular; D050259:Genes, Mitochondrial; D049810:Genetic Speciation; D014644:Genetic Variation; D007076:Iguanas / Q000145:classification / Q000235:genetics*; D016013:Likelihood Functions; D008800:Mexico; D009245:NADH Dehydrogenase / Q000235:genetics; D010802:Phylogeny; D058974:Phylogeography; D030162:Reptilian Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: C098483:NADH dehydrogenase subunit 4; D030162:Reptilian Proteins; D009245:NADH Dehydrogenase; D000251:Adenosine Triphosphatases