Department of Biological Sciences, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea.
PLoS One. 2021 Apr 8;16(4):e0249752. doi: 10.1371/journal.pone.0249752. eCollection 2021.
Saussurea polylepis Nakai is an herbaceous perennial endemic to Korea and is highly restricted to several continental islands in the southwestern part of the Korean Peninsula. Given its very narrow geographical distribution, it is more vulnerable to anthropogenic activities and global climate changes than more widely distributed species. Despite the need for comprehensive genetic information for conservation and management, no such population genetic studies of S. polylepis have been conducted. In this study, genetic diversity and population structure were evaluated for 97 individuals from 5 populations (Gwanmaedo, Gageodo, Hongdo, Heusando, and Uido) using 19 polymorphic microsatellites. The populations were separated by a distance of 20-90 km. We found moderate levels of genetic diversity in S. polylepis (Ho = 0.42, He = 0.43). This may be due to long lifespans, outcrossing, and gene flow, despite its narrow range. High levels of gene flow (Nm = 1.76, mean Fst = 0.09), especially from wind-dispersed seeds, would contribute to low levels of genetic differentiation among populations. However, the small population size and reduced number of individuals in the reproductive phase of S. polylepis can be a major threat leading to inbreeding depression and genetic diversity loss. Bayesian cluster analysis revealed three significant structures at K = 3, consistent with DAPC and UPGMA. It is thought that sea level rise after the last glacial maximum may have acted as a geographical barrier, limiting the gene flow that would lead to distinct population structures. We proposed the Heuksando population, which is the largest island inhabited by S. polylepis, as a source population because of its large population size and high genetic diversity. Four management units (Gwanmaedo, Gageodo, Hongdo-Heuksando, and Uido) were suggested for conservation considering population size, genetic diversity, population structure, unique alleles, and geographical location (e.g., proximity).
雪莲是一种多年生草本植物，仅分布于朝鲜半岛西南部的几个大陆岛屿，分布范围非常狭窄。由于其分布范围狭窄，与分布范围较广的物种相比，它更容易受到人为活动和全球气候变化的影响。尽管需要全面的遗传信息来进行保护和管理，但对雪莲的种群遗传研究尚未进行。在这项研究中，使用 19 个多态性微卫星，对来自 5 个种群（观德岛、加德岛、洪岛、月尾岛和郁陵岛）的 97 个个体进行了遗传多样性和种群结构评估。这些种群之间的距离为 20-90 公里。我们发现雪莲的遗传多样性水平中等（Ho = 0.42，He = 0.43）。这可能是由于其狭窄的分布范围，但具有较长的寿命、异交和基因流。高水平的基因流（Nm = 1.76，平均 Fst = 0.09），特别是来自风传播的种子，有助于降低种群之间的遗传分化。然而，雪莲的小种群规模和繁殖阶段个体数量减少可能是导致近交衰退和遗传多样性丧失的主要威胁。贝叶斯聚类分析显示，在 K = 3 时存在三个显著结构，与 DAPC 和 UPGMA 一致。海平面上升可能在末次冰期后成为地理障碍，限制了导致不同种群结构的基因流动。我们提出将月尾岛（Heuksando）种群作为一个大的雪莲栖息岛屿作为一个源种群，因为其种群规模大，遗传多样性高。考虑到种群规模、遗传多样性、种群结构、独特等位基因和地理位置（如邻近度），建议将 4 个管理单元（观德岛、加德岛、洪岛-月尾岛和郁陵岛）作为保护单元。
