School of Environment and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China.
Mol Biol Rep. 2022 Jun;49(6):4389-4397. doi: 10.1007/s11033-022-07274-8. Epub 2022 May 12.
Daphnia magna belongs to the Cladocera order and plays an important role in the aquatic ecosystem. With the intensification of water pollution, the wild population of D. magna has declined rapidly in recent years, and insufficient molecular markers have limited effective research and conservation of this species.
26 novel microsatellite (SSR) markers were developed in an artificially domesticated D. magna and 12 wild D. magna populations using restriction site-associated DNA sequencing (RAD-seq). The results showed that the observed heterozygosity (Ho) and expected heterozygosity (He) ranged from 0.083 to 0.999 and 0.085 to 0.862, respectively. The PIC ranged from 0.368 to 0.805. These results indicate that the developed SSR marker is highly polymorphic. Nei's genetic identity (H) ranged from 0.0926 to 0.3462. Shannon's Information index (I) ranged from 0.1333 to 0.4799. Genetic distance and Nei's genetic identity analysis, NJ tree diagram analysis, and PCoA analysis were conducted on populations of D. magna from different regions. The results show that the D. magna genetic relationship between Liaoning and Shanxi, Hunan and Anhui, and Beijing and Hainan are relatively close, while the genetic structure of D. magna in Guangdong, Jiangsu, and Sichuan is quite different from other sampling sites. An analysis of population genetic structure divided the D. magna samples into two major groups.
These results indicate that the genetic structure of D. magna differs considerably in different regions. Our research results and the newly developed polymorphic SSR markers for D. magna are of great significance in terms of the genetic breeding of D. magna, identification of wild and artificially domesticated populations and conservation genetics research.
大型溞（Daphnia magna）属于枝角目，在水生态系统中发挥着重要作用。近年来，随着水污染的加剧，大型溞的野生种群数量迅速减少，而分子标记的不足限制了对该物种的有效研究和保护。
采用 RAD-seq 技术，从人工养殖的大型溞和 12 个野生大型溞群体中开发了 26 个新的微卫星（SSR）标记。结果表明，观测杂合度（Ho）和期望杂合度（He）范围分别为 0.083-0.999 和 0.085-0.862，多态信息含量（PIC）范围为 0.368-0.805。这些结果表明，开发的 SSR 标记高度多态。Nei 的遗传身份（H）范围为 0.0926-0.3462。Shannon 的信息指数（I）范围为 0.1333-0.4799。对来自不同地区的大型溞种群进行遗传距离和 Nei 的遗传身份分析、NJ 树图分析和 PCoA 分析。结果表明，辽宁与山西、湖南与安徽、北京与海南的大型溞遗传关系较为密切，而广东、江苏、四川的大型溞遗传结构与其他采样点有较大差异。种群遗传结构分析将大型溞样本分为两大组。
这些结果表明，不同地区的大型溞遗传结构存在较大差异。本研究结果和新开发的大型溞多态性 SSR 标记，对于大型溞的遗传育种、野生和人工养殖群体的鉴定以及保护遗传学研究具有重要意义。
