title: Contrasting patterns of DNA variation in natural populations of two related conifers, Cryptomeria japonica and Taxodium distichum (Cupressaceae sensu lato).
abstract: We investigated DNA variation within and between two closely related conifers, Cryptomeria japonica and Taxodium distichum, at nuclear loci encoding ferredoxin, glutamyl-tRNA reductase, lycopene beta cyclase, and phosphoribosylanthranilate transferase. Average nucleotide diversity at silent sites was estimated to be 0.0035 (SE 0.0012) in C. japonica and 0.0058 (SE 0.0006) in T. distichum. One population in C. japonica was differentiated from the others but generally there was not much differentiation among populations or varieties within the two species. However, the two species seemed to differ in frequency spectra of DNA polymorphisms. Excesses of intermediate-frequency variants were found in C. japonica, whereas excesses of both rare and high-frequency variants were found in T. distichum, which suggested different histories of population structures in the two species. Deviations from the standard neutral expectations in DNA polymorphisms were found by applications of neutrality tests. The results show that actions of selection to respective loci seem to differ between the two species, indicating differences of interaction among evolutionary factors.
authors.affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kado
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ushio
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yoshimaru
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tsumura
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tachida
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000235:genetics; D000582:Amidophosphoribosyltransferase / Q000235:genetics; D001483:Base Sequence; D032485:Cryptomeria / Q000235:genetics*; D019143:Evolution, Molecular; D005288:Ferredoxins / Q000235:genetics; D017343:Genes, Plant; D049810:Genetic Speciation; D014644:Genetic Variation; D019753:Intramolecular Lyases / Q000235:genetics; D008969:Molecular Sequence Data; D035261:Plant Components, Aerial / Q000235:genetics; D011110:Polymorphism, Genetic; D012689:Sequence Homology, Nucleic Acid; D032489:Taxodium / Q000235:genetics*
chemical_list: D005288:Ferredoxins; D000445:Aldehyde Oxidoreductases; C067282:glutamyl tRNA reductase; D000582:Amidophosphoribosyltransferase; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase