Rhododendron brachycarpum is an ecologically important tree species with a narrow, fragmented geographic range in East Asia. R. brachycarpum is distributed primarily in Korea and Japan, with two small isolated populations in the Russian Far East. We obtained 124 samples from seven populations of R. brachycarpum , representing all geographical regions of its entire natural range, and we utilized microsatellite markers to estimate the level of genetic variation within and between populations. A total of 200 alleles based on 14 nuclear microsatellites loci were identified. High diversity ( H e = 0.556–0.626) was observed in populations from Korea and Japan. In contrast, in peripheral populations from Russia diversity was quite low ( H e = 0.100–0.369) with a high coefficient of inbreeding ( F IS = 0.471–0.526). Strong population differentiation ( F ST = 0.356) and clear distinction among the geographical groups ( F CT = 0.227) were revealed. Bayesian clustering and principal coordinate analyses indicated that two Russian populations, Sikhote-Alin and Iturup Island, represent extremes of two different migration routes, with one derived from the mainland and one from Japan.

中文翻译：

---

以SSR标记为特征的东亚杜鹃花（杜鹃花科）遗传多样性和种群结构的洞察

短果杜鹃是一种生态上重要的树种，在东亚地区分布狭窄、分散。R. brachycarpum 主要分布在韩国和日本，在俄罗斯远东地区有两个小的孤立种群。我们从 R. brachycarpum 的七个种群中获得了 124 个样本，代表了其整个自然范围的所有地理区域，我们利用微卫星标记来估计种群内和种群之间的遗传变异水平。共鉴定了基于 14 个核微卫星位点的 200 个等位基因。在韩国和日本的人群中观察到高度多样性（He = 0.556–0.626）。相比之下，来自俄罗斯的外围种群的多样性非常低（He = 0.100-0.369），近亲繁殖系数很高（F IS = 0.471-0.526）。揭示了强烈的人口分化（ F ST = 0.356）和地理组之间的明显区别（ F CT = 0.227）。贝叶斯聚类和主坐标分析表明，两个俄罗斯种群 Sikhote-Alin 和 Iturup 岛代表了两种不同迁徙路线的极端情况，一种来自大陆，一种来自日本。