Data from: Genomic-wide displacement and shift of the hybrid zone in the Japanese fire-bellied newt

Hybridizations on a secondary contact zone between 2 diverged lineages can have various evolutionary consequences, including the genetic replacement of one lineage by another. We detected such a case between 2 lineages (the Central and Western lineages) of the Japanese fire-bellied newt, Cynops pyrrhogaster in the Chugoku district of western Japan. We genotyped 269 individuals from 30 localities using the mitochondrial cytochrome b gene and 11 microsatellite loci. The mitochondrial DNA (mtDNA) analysis revealed that the 2 lineages were mostly distributed parapatrically to each other but co-occurred around the contact zone, whereas the microsatellite analyses indicated the presence of a hybrid zone. Geographic cline analysis revealed that the cline width of mtDNA is wider than the width of the microsatellite loci. The migration rate estimation and the NewHybrids analysis revealed that the Central lineage has expanded their range into the range of the hybrid zone, suggesting the possibility of range displacement of the 2 lineages as a consequence of the shift of their hybrid zone. We explored the process of asymmetric gene flow associated with the invasion of the Central lineage to explain this pattern.

两个分化支系间的次级接触带（secondary contact zone）上的杂交事件可引发多种进化后果，其中包括一个支系被另一支系的遗传替代。我们在日本西部中国地方的日本红腹蝾螈（Cynops pyrrhogaster）的两个支系——中央支系与西部支系——间检测到了此类案例。我们对采自30个采样点的269个个体进行了基因分型，所用分子标记为线粒体细胞色素b基因与11个微卫星位点（microsatellite loci）。线粒体DNA（mitochondrial DNA, mtDNA）分析结果显示，这两个支系整体呈邻域分布，但在接触带周边区域存在同域共存现象；而微卫星分析则表明该区域存在杂交带（hybrid zone）。地理渐变分析（geographic cline analysis）显示，mtDNA的渐变宽度（cline width）大于微卫星位点的渐变宽度。迁移率估计（migration rate estimation）与NewHybrids分析结果表明，中央支系已将其分布范围扩张至杂交带的分布区内，这提示两个支系的分布区置换（range displacement）可能因杂交带的移动而发生。我们针对中央支系入侵所引发的不对称基因流（asymmetric gene flow）过程展开探讨，以解释该观测模式。