Understanding the factors influencing the current distribution of genetic diversity across a species range is one of the main questions of evolutionary biology, especially given the increasing threat to biodiversity posed by climate change. Historical demographic processes such as population expansion or bottlenecks and decline are known to exert a predominant influence on past and current levels of genetic diversity, and revealing this demo‐genetic history can have immediate conservation implications. We used a whole‐exome capture sequencing approach to analyze polymorphism across the gene space of red spruce (Picea rubens Sarg.), an endemic and emblematic tree species of eastern North America high‐elevation forests that are facing the combined threat of global warming and increasing human activities. We sampled a total of 340 individuals, including populations from the current core of the range in northeastern USA and southeastern Canada and from the southern portions of its range along the Appalachian Mountains, where populations occur as highly fragmented mountaintop “sky islands.” Exome capture baits were designed from the closely relative white spruce (P. glauca Voss) transcriptome, and sequencing successfully captured most regions on or near our target genes, resulting in the generation of a new and expansive genomic resource for studying standing genetic variation in red spruce applicable to its conservation. Our results, based on over 2 million exome‐derived variants, indicate that red spruce is structured into three distinct ancestry groups that occupy different geographic regions of its highly fragmented range. Moreover, these groups show small N_e, with a temporal history of sustained population decline that has been ongoing for thousands (or even hundreds of thousands) of years. These results demonstrate the broad potential of genomic studies for revealing details of the demographic history that can inform management and conservation efforts of nonmodel species with active restoration programs, such as red spruce.

中文翻译：

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全外显子组测序揭示红云杉（Picea rubens）有效种群规模的长期下降


了解影响物种范围内遗传多样性当前分布的因素是进化生物学的主要问题之一，特别是考虑到气候变化对生物多样性造成的日益严重的威胁。已知人口扩张或瓶颈和下降等历史人口统计过程对过去和当前的遗传多样性水平产生主要影响，揭示这种人口遗传历史可以立即产生保护意义。我们使用全外显子组捕获测序方法来分析红云杉 ( Picea rubens Sarg.) 基因空间的多态性，红云杉是北美东部高海拔森林的特有和标志性树种，面临着全球变暖和气候变化的综合威胁。人类活动增加。我们总共对 340 只个体进行了采样，其中包括来自美国东北部和加拿大东南部目前核心山脉的种群，以及来自阿巴拉契亚山脉沿线的山脉南部部分的种群，那里的种群以高度分散的山顶“天空岛屿”的形式存在。外显子组捕获诱饵是根据密切相关的白云杉 ( P. glauca Voss) 转录组设计的，测序成功捕获了我们目标基因上或附近的大部分区域，从而产生了新的、广泛的基因组资源，用于研究红云杉的常备遗传变异云杉适用于其养护。我们的结果基于超过 200 万个外显子组衍生的变异，表明红云杉分为三个不同的祖先群体，它们占据了其高度分散的范围的不同地理区域。 此外，这些群体的_Ne较小，其人口持续减少的时间历史已经持续了数千年（甚至数十万年）。这些结果证明了基因组研究在揭示人口历史细节方面的广泛潜力，可以为红云杉等非模式物种的积极恢复计划的管理和保护工作提供信息。