title: Origin of Boundary Populations in Medaka (Oryzias latipes Species Complex).
abstract: The Japanese wild population of the medaka fish (Oryzias latipes species complex) comprises two genetically distinct groups, the Northern and the Southern Populations, with boundary populations having a unique genotype. It is thought that the boundary populations have been formed through introgressive hybridization between the two groups, because they are fixed with the Northern alleles at two allozymic loci, with the Southern alleles at two other loci, and have a unique allele at one locus. In this study, we examined the genetic population structure of the boundary populations using genome-wide single nucleotide polymorphism (SNP) data. Most SNPs of the Toyooka population, a typical boundary population, were shared with the Northern Population, some were shared with the Southern Population, and the remaining SNPs were unique to this population, suggesting that the boundary populations originated and diverged from the Northern Population. Further analyses of different populations using SNPs at eight genomic loci indicated that the boundary populations at different locations share similar genomic constitutions, and can be genetically distinguished from typical Northern Populations by unique SNPs. In addition, the boundary populations in the Maruyama River Basin had Northern mitochondrial DNA (mtDNA), while others, from the Fukuda and Kishida River Basins and from the Kumihama Bay area, had Southern mtDNA. These findings suggested that the boundary populations originated from the Northern Population, and then their genomes diverged as a result of geographical isolation, followed by mtDNA introgression from the Southern Population that occurred independently in some populations.
authors.affiliation: 1 Laboratory of Bioresources, National Institute for Basic Biology, Okazaki 444-8585, Japan.|2 Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Takehana
authors.affiliation: 2 Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Sakai
authors.affiliation: 3 Genome Biology Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Narita
authors.affiliation: 2 Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sato
authors.affiliation: 1 Laboratory of Bioresources, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Naruse
authors.affiliation: 2 Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sakaizumi
mesh_terms: D063147:Animal Distribution / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics; D014644:Genetic Variation; D016678:Genome; D007564:Japan; D008969:Molecular Sequence Data; D009990:Oryzias / Q000235:genetics*; D010802:Phylogeny
chemical_list: D004272:DNA, Mitochondrial
keywords: Oryzias latipes; Oryzias sakaizumii; hybrid zone; phylogeography; single nucleotide polymorphism