Survival in hyperarid deserts is a major challenge for life in general and for plants in particular. The Atacama Desert presents harsh conditions such as limited rainfall, crusted soils, high soil salinity, high altitude, and intense solar radiation. These conditions, together with paleoclimatic variations over the last 10 million years, have influenced the genetic structure and connectivity of plant populations, resulting in a diverse flora with high endemism. However, the diversification of most lineages appears to be relatively recent, in contrast to the reported age of the Atacama Desert and the onset and expansion of hyperarid conditions since the late Oligocene and early Miocene. A prominent exception is (Loasaceae), which is thought to be endemic to the Atacama since the Eocene. However, it is still not understood why this plant has been successful in adapting to the harshening environmental conditions. To investigate its genetic structure in relation to the history of the Atacama Desert, we studied 186 individuals from 11 populations using genotyping-by-sequencing (GBS). A total of nearly 56 k genome-wide single nucleotide polymorphisms (SNPs) were analyzed for population structure and genetic diversity. We identified four genetic clusters corresponding to geographic regions: the coastal region south of Tocopilla, the Cordillera de la Costa around Chañaral, and the Copiapó catchment 1 and 2. Genetic diversity within and between these clusters was analyzed along with rainfall, altitude, soil composition and landscape data. Although the genetic data support `isolation by distance’ as a major factor for genetic divergence between populations, the study also reveals the influence of topography on the distribution of and highlights the role of hydrologically connected watersheds and rivers in plant migration and colonization. Soil composition appears to have a negligible influence. Hence topography and hydrology shape the species' evolutionary trajectory and genetic diversity. Understanding these patterns in lets one draw general conclusions about adaptation and survival strategies of plants in extreme desert environments such as the Atacama

中文翻译：

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地理和气候背景下阿塔卡马沙漠灌木Huidobria chilensis的遗传多样性

在极度干旱的沙漠中生存是对一般生命，特别是对植物来说的一个重大挑战。阿塔卡马沙漠气候恶劣，降雨量有限，土壤结皮，土壤盐分高，海拔高，太阳辐射强烈。这些条件，加上过去一千万年的古气候变化，影响了植物种群的遗传结构和连通性，导致了具有高度特有性的多样化植物群。然而，与阿塔卡马沙漠报道的年龄以及自渐新世晚期和中新世早期以来超级干旱条件的发生和扩展相比，大多数谱系的多样化似乎是相对较新的。一个突出的例外是（Loasaceae），它被认为是自始新世以来阿塔卡马地区的特有种。然而，人们仍然不明白为什么这种植物能够成功地适应恶劣的环境条件。为了研究其与阿塔卡马沙漠历史相关的遗传结构，我们使用测序基因分型 (GBS) 对来自 11 个种群的 186 个个体进行了研究。总共分析了近 56 k 个全基因组单核苷酸多态性 (SNP) 的群体结构和遗传多样性。我们确定了与地理区域相对应的四个遗传簇：托科皮亚 (Tocopilla) 以南的沿海地区、查纳拉尔 (Chañaral) 周围的科迪拉德拉科斯塔 (Cordillera de la Costa) 以及科皮亚波 (Copiapó) 流域 1 和 2。我们对这些簇内部和之间的遗传多样性以及降雨量、海拔、土壤成分进行了分析和景观数据。尽管遗传数据支持“距离隔离”是种群间遗传分化的主要因素，但该研究还揭示了地形对分布的影响，并强调了水文相连的流域和河流在植物迁徙和定殖中的作用。土壤成分的影响似乎可以忽略不计。因此，地形和水文塑造了物种的进化轨迹和遗传多样性。了解这些模式让我们得出关于植物在阿塔卡马等极端沙漠环境中的适应和生存策略的一般结论