Diversification and demographic responses are key processes shaping species evolutionary history. Yet we still lack a full understanding of ecological mechanisms that shape genetic diversity at different spatial scales upon rapid environmental changes. In this study, we examined genetic differentiation in an extremophilic grass Puccinellia pamirica and factors affecting its population dynamics among the occupied hypersaline alpine wetlands on the arid Pamir Plateau in Central Asia. Using genomic data, we found evidence of fine-scale population structure and gene flow among the localities established across the high-elevation plateau as well as fingerprints of historical demographic expansion. We showed that an increase in the effective population size could coincide with the Last Glacial Period, which was followed by the species demographic decline during the Holocene. Geographic distance plays a vital role in shaping spatial genetic structure of P. pamirica alongside with isolation-by-environment and habitat fragmentation. Our results highlight a complex history of divergence and gene flow in this species-poor alpine region during the Late Quaternary. We demonstrate that regional climate specificity and a shortage of non-climate data largely impede predictions of future range changes of the alpine extremophile using ecological niche modelling. This study emphasises the importance of fine-scale environmental heterogeneity for population dynamics and species distribution shifts.

中文翻译：

---

进化混乱中的高山极端植物：中亚生物多样性热点地区嗜盐草的复杂多样化模式和人口响应


多样化和人口反应是塑造物种进化史的关键过程。然而，我们仍然缺乏对环境快速变化时在不同空间尺度上塑造遗传多样性的生态机制的充分理解。在这项研究中，我们研究了中亚干旱的帕米尔高原上被占领的高盐高山湿地中极端微生物草碱茅的遗传分化以及影响其种群动态的因素。利用基因组数据，我们发现了高海拔高原各地点之间的精细人口结构和基因流动的证据，以及历史人口扩张的指纹。我们表明，有效种群规模的增加可能与末次冰河期同时发生，随后是全新世物种种群数量的下降。地理距离在塑造帕米里卡空间遗传结构以及环境隔离和栖息地破碎化方面发挥着至关重要的作用。我们的研究结果强调了晚第四纪这个物种贫乏的高山地区复杂的分化和基因流动历史。我们证明，区域气候特异性和非气候数据的缺乏在很大程度上阻碍了利用生态位模型对高山极端微生物未来范围变化的预测。这项研究强调了细尺度环境异质性对于种群动态和物种分布变化的重要性。