title: Selection on codon usage and base composition in Drosophila americana.
abstract: We have used a polymorphism dataset on introns and coding sequences of X-linked loci in Drosophila americana to estimate the strength of selection on codon usage and/or biased gene conversion (BGC), taking into account a recent population expansion detected by a maximum-likelihood method. Drosophila americana was previously thought to have a stable demographic history, so that this evidence for a recent population expansion means that previous estimates of selection need revision. There was evidence for natural selection or BGC favouring GC over AT variants in introns, which is stronger for GC-rich than GC-poor introns. By comparing introns and coding sequences, we found evidence for selection on codon usage bias, which is much stronger than the forces acting on GC versus AT basepairs in introns.
authors.affiliation: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK. sdeproce@staffmail.ed.ac.uk
authors.forename: Sophie Marion
authors.initials: SM
authors.lastname: de Procé
authors.forename: Kai
authors.initials: K
authors.lastname: Zeng
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Betancourt
authors.forename: Brian
authors.initials: B
authors.lastname: Charlesworth
mesh_terms: D000818:Animals; D001482:Base Composition / Q000235:genetics*; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D016013:Likelihood Functions; D008297:Male; D008923:Missouri; D008969:Molecular Sequence Data; D011157:Population Dynamics; D012641:Selection, Genetic / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D003062:Codon