Miura Osamu, Urabe Misako, Mori Hideaki, Chiba Satoshi
Faculty of Agriculture and Marine Science Kochi University Nankoku Japan.
Department of Ecosystem Studies School of Environmental Science The University of Shiga Prefecture Hikone Japan.
Ecol Evol. 2020 Jul 14;10(15):8186-8196. doi: 10.1002/ece3.6523. eCollection 2020 Aug.
Biogeography and genetic variation of freshwater organisms are influenced not only by current freshwater connections but also by past drainage networks. The Seto Inland Sea is a shallow enclosed sea in Japan, but geological evidence showed that a large freshwater drainage had intermittently appeared in this area between the late Pliocene and Pleistocene. Here, we demonstrated that this paleodrainage greatly affected the genetic variation of the East Asian freshwater snails, spp. We found that the mtDNA haplotypes originated in the Lake Biwa endemic species at the upstream side of the paleodrainage were frequently observed in the riverine species at its downstream side. The genome-wide DNA and morphological analyses consistently showed that there was no clear evidence of nuclear introgression between the Lake Biwa endemics and riverine species. These results suggest that the large paleodrainage had facilitated mitochondrial introgression and had broadly spread the introgressed mtDNA haplotypes to its downstream region around the Seto Inland Sea. Our study highlights the role of paleodrainages in shaping the genetic variation of freshwater organisms.
淡水生物的生物地理学和遗传变异不仅受到当前淡水连通性的影响，还受到过去排水网络的影响。濑户内海是日本的一个浅封闭海，但地质证据表明，在上新世晚期和更新世之间，该地区曾间歇性地出现过大型淡水排水系统。在此，我们证明了这种古排水系统对东亚淡水蜗牛的遗传变异产生了重大影响。我们发现，起源于古排水系统上游琵琶湖特有物种的线粒体DNA单倍型，在其下游的河流物种中经常被观察到。全基因组DNA和形态学分析一致表明，没有明确证据表明琵琶湖特有物种和河流物种之间存在核基因渗入。这些结果表明，大型古排水系统促进了线粒体基因渗入，并将渗入的线粒体DNA单倍型广泛传播到濑户内海周围的下游地区。我们的研究突出了古排水系统在塑造淡水生物遗传变异中的作用。
