Comparative genomic analysis using inter-specific hybrids between O. luzonensis and 0. curvinotus

对近缘种的比较基因组分析表明，除了近缘种的O. latipes和O. curvinotus外，不同种间的性染色体和性别决定基因存在差异。性染色体为连锁群（LG） 01，均具有XX-XY性别决定系统。O. luzonensis是O. curvinotus的姐妹种，其性染色体与O. latipes的LG12同源，性别决定系统为XX-XY。雌雄同体的性染色体与LG02同源，性别决定系统为XX-XY。O. javanicus和O. habsi的性染色体分别与LG16和LG05同源，性别决定系统为ZZ-ZW。本文首次在稻属近缘种中描述了ZZ-ZW性别决定系统。舞女的性染色体与LG10同源，性别决定系统为XX-XY。从系统发育的角度看，O. latipes、O. curvinoutus、O. luzonensis和O. mekongnensis为单系物种（latipes种群），O. javanicus、O. habsi和O. dancena具有共同祖先（javanicus种群），O. dancena是javanicus种群中分化最基础的物种。这些结果表明，爪哇种群的共同祖先可能具有XX-XY性别决定系统和ZZ-ZW性别决定系统，从而导致爪哇种群和habsi种群的进化。medaka近缘种在全球范围内具有较好的同源性。

Comparative genomic analysis using medaka related species revealed that the sex chromosomes and sex determination genes differ from species to species except O. latipes and O. curvinotus even in the closely relates species. Sex chromosomes of O. latipes and O. curvinotus were linkage group (LG) 01 and both species had XX-XY sex determination system. Sex chromosome of O. luzonensis, which is the sister species of O. curvinotus, was orthologous to LG12 of O. latipes and its sex determination system was XX-XY. Sex chromosome of O. mekongensis was orthologous to LG02 and its sex determination system was XX-XY. O. javanicus and O. habsi had the sex chromosomes which were orthologous to LG16 and LG05, respectively and their sex determination systems were ZZ-ZW. This is the first description of ZZ-ZW sex determination system in the Oryzias related species. Sex chromosome of O. dancena was orthologous to LG10 and sex determination system was XX-XY. From phylogenetic point of view, O. latipes, O. curvinoutus, O. luzonensis and O. mekongnensis are monophyletic (the latipes species group) and O. javanicus, O. habsi and O. dancena share the common ancestor (the javanicus species group) and O. dancena was the most basally diverged species in the javanicus species group. These results suggest the common ancestor of the javanicus species group might have XX-XY sex determination system and ZZ-ZW system evolved in the lineage leading to O. javanicus and O. habsi. The global synteny of medaka related species were well conserved each other.