title: Patterns of nucleotide diversity at the methionine synthase locus in fragmented and continuous populations of a wind-pollinated tree, Quercus mongolica var. crispula.
abstract: Genetic variation is usually high within populations, and differentiation is usually low among populations of wind-pollinated outcrossing trees. As a result, population contraction causes little change in the degree of genetic diversity and differentiation among populations. The aim of this work was to determine whether or not a recent population decline has influenced the allele frequency spectrum and association among variants of different sites on the nuclear housekeeping locus methionine synthase (1376-1418 bp in length) in the oak species Quercus mongolica var. crispula. A total of 122 sequences from 18 populations were randomly sampled and analyzed in this study. Results showed that nucleotide variation was generally high within populations, and differentiation was very low among populations. Genetic diversity was slightly reduced in samples taken from the area with a recent strong reduction in population size. Nevertheless, the allele frequency spectrum was skewed toward rare variants, and the association among variants of different sites was significantly more nonrandom within these samples compared with those from the area without such a population size reduction. This pattern was robustly supported by coalescent simulations.
authors.affiliation: Faculty of Agriculture, Ehime University, Tarumi, Matsuyama, Japan. adaptation.global.warming@gmail.com
authors.forename: Nguyen D
authors.initials: ND
authors.lastname: Quang
authors.forename: Sosaku
authors.initials: S
authors.lastname: Ikeda
authors.forename: Ko
authors.initials: K
authors.lastname: Harada
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000235:genetics*; D001483:Base Sequence; D003198:Computer Simulation; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D007564:Japan; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011157:Population Dynamics; D029963:Quercus / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase