The vast territory of East Asia, including southwestern Beringia, is considered to have been almost ice free during the Pleistocene. Cold-resistant flora may have persisted in this region expanding or contracting its range during the climate cooling. Only a few plant genera have been studied with a sampling area across their entire geographic range in East Asia; therefore, the understanding of the biogeographic history of alpine flora in this region remains limited. In the present study, genetic variation and population structure in 21 populations of the alpine shrub Rhododendron aureum across its range in East Asia were assessed using 18 microsatellite loci. Phylogenetic analyses revealed three main genetic groups: Siberia, Northeast, and North Pacific. According to the geographical pattern of genetic diversity, the North Pacific group includes populations from Kamchatka, south of Russian Far East, and territories close to central Japan. This group is the most diverse and likely diverged earlier than the Siberia and Northeast groups. Ecological niche modeling predicts range expansion of this species during the period of cooling and, together with demographic history, suggests that the divergence between the three main genetic groups predated the Last Glacial Maximum. Similar to other cold-resistant species such as Larix sibirica and Juniperus communis, the pattern of genetic diversity of R. aureum supports the survival of the species at high latitudes during the Pleistocene with limited contribution of the southern populations to expansion of the species range to the Northeast region and Siberia.

东亚的广阔领土，包括白令陆桥西南部，被认为在更新世期间几乎没有冰。耐寒植物群可能在该地区持续存在，在气候变冷期间扩大或缩小其范围。只有少数植物属在东亚的整个地理范围内进行了采样区域研究；因此，对该地区高山植物群的生物地理历史的了解仍然有限。在本研究中，高山灌木杜鹃花21 个居群的遗传变异和种群结构使用 18 个微卫星位点对其在东亚范围内的分布进行了评估。系统发育分析揭示了三个主要的遗传群：西伯利亚、东北和北太平洋。根据遗传多样性的地理格局，北太平洋群体包括来自堪察加半岛、俄罗斯远东以南和靠近日本中部地区的人群。这个群体是最多样化的，可能比西伯利亚和东北部群体更早分化。生态位模型预测了该物种在冷却期间的范围扩张，并与人口统计历史一起表明，三个主要遗传组之间的差异早于末次盛冰期。类似于西伯利亚落叶松和刺柏等其他耐寒树种，金黄色葡萄球菌的遗传多样性模式支持该物种在更新世期间在高纬度地区的生存，而南部种群对该物种范围向东北地区和西伯利亚的扩张的贡献有限。