title: Anolis sex chromosomes are derived from a single ancestral pair.
abstract: To explain the frequency and distribution of heteromorphic sex chromosomes in the lizard genus Anolis, we compared the relative roles of sex chromosome conservation versus turnover of sex-determining mechanisms. We used model-based comparative methods to reconstruct karyotype evolution and the presence of heteromorphic sex chromosomes onto a newly generated Anolis phylogeny. We found that heteromorphic sex chromosomes evolved multiple times in the genus. Fluorescent in situ hybridization (FISH) of repetitive DNA showed variable rates of Y chromosome degeneration among Anolis species and identified previously undetected, homomorphic sex chromosomes in two species. We confirmed homology of sex chromosomes in the genus by performing FISH of an X-linked bacterial artificial chromosome (BAC) and quantitative PCR of X-linked genes in multiple Anolis species sampled across the phylogeny. Taken together, these results are consistent with long-term conservation of sex chromosomes in the group. Our results pave the way to address additional questions related to Anolis sex chromosome evolution and describe a conceptual framework that can be used to evaluate the origins and evolution of heteromorphic sex chromosomes in other clades.
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota, 321 Church St. SE, Minneapolis, Minnesota, 55455; Bell Museum of Natural History, University of Minnesota, 10 Church St. SE, Minneapolis, Minnesota, 55455. gambl007@umn.edu.
authors.forename: Tony
authors.initials: T
authors.lastname: Gamble
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Geneva
authors.forename: Richard E
authors.initials: RE
authors.lastname: Glor
authors.forename: David
authors.initials: D
authors.lastname: Zarkower
mesh_terms: D000818:Animals; D020732:Cytogenetic Analysis; D019143:Evolution, Molecular; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D008116:Lizards / Q000235:genetics*; D008297:Male; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D014960:X Chromosome; D014998:Y Chromosome
keywords: Cytogenetics; X chromosome; homology; phylogeny; reptile; sex determination