title: Rapid evolution of yeast centromeres in the absence of drive.
abstract: To find the most rapidly evolving regions in the yeast genome we compared most of chromosome III from three closely related lineages of the wild yeast Saccharomyces paradoxus. Unexpectedly, the centromere appears to be the fastest-evolving part of the chromosome, evolving even faster than DNA sequences unlikely to be under selective constraint (i.e., synonymous sites after correcting for codon usage bias and remnant transposable elements). Centromeres on other chromosomes also show an elevated rate of nucleotide substitution. Rapid centromere evolution has also been reported for some plants and animals and has been attributed to selection for inclusion in the egg or the ovule at female meiosis. But Saccharomyces yeasts have symmetrical meioses with all four products surviving, thus providing no opportunity for meiotic drive. In addition, yeast centromeres show the high levels of polymorphism expected under a neutral model of molecular evolution. We suggest that yeast centromeres suffer an elevated rate of mutation relative to other chromosomal regions and they change through a process of "centromere drift," not drive.
authors.affiliation: Division of Biology, Imperial College London, Ascot SL5 7PY, United Kingdom.
authors.forename: Douda
authors.initials: D
authors.lastname: Bensasson
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zarowiecki
authors.forename: Austin
authors.initials: A
authors.lastname: Burt
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Koufopanou
mesh_terms: D020856:AT Rich Sequence / Q000235:genetics; D001483:Base Sequence; D002503:Centromere / Q000235:genetics*; D015825:Chromosomes, Fungal / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal