State Key Laboratory of Plant Diversity and Specialty Crops, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
New Phytol. 2024 Oct;244(1):277-291. doi: 10.1111/nph.20036. Epub 2024 Aug 12.
Understanding how life history shapes genetic diversity is a fundamental issue in evolutionary biology, with important consequences for conservation. However, we still have an incomplete picture of the impact of life history on genome-wide patterns of diversity, especially in long-lived semelparous plants. Puya raimondii is a high-altitude semelparous species from the Andes that flowers at 40-100 years of age. We sequenced the whole genome and estimated the nucleotide diversity of 200 individuals sampled from nine populations. Coalescent-based approaches were then used to infer past population dynamics. Finally, these results were compared with results obtained for the iteroparous species, Puya macrura. The nine populations of P. raimondii were highly divergent, highly inbred, and carried an exceptionally high genetic load. They are genetically depauperate, although, locally in the genome, balancing selection contributed to the maintenance of genetic polymorphism. While both P. raimondii and P. macrura went through a severe bottleneck during the Pleistocene, P. raimondii did not recover from it and continuously declined, while P. macrura managed to bounce back. Our results demonstrate the importance of life history, in particular generation time and reproductive strategy, in affecting population dynamics and genomic variation, and illustrate the genetic fragility of long-lived semelparous plants.
了解生活史如何塑造遗传多样性是进化生物学中的一个基本问题，对保护具有重要意义。然而，我们仍然不完全了解生活史对全基因组多样性模式的影响，特别是在长寿的单次繁殖植物中。Puya raimondii 是一种来自安第斯山脉的高海拔单次繁殖物种，其开花年龄为 40-100 年。我们对其进行了全基因组测序，并对来自九个种群的 200 个个体的核苷酸多样性进行了估计。然后，我们使用基于合并的方法来推断过去的种群动态。最后，将这些结果与多次繁殖物种 Puya macrura 的结果进行比较。九个 P. raimondii 种群高度分化、高度自交且携带极高的遗传负荷。尽管在局部基因组中，平衡选择有助于维持遗传多态性，但它们的遗传多样性匮乏。虽然 P. raimondii 和 P. macrura 在更新世都经历了严重的瓶颈期，但 P. raimondii 未能从中恢复并持续下降，而 P. macrura 则成功反弹。我们的研究结果表明，生活史，特别是世代时间和繁殖策略，对种群动态和基因组变异有重要影响，并说明了长寿单次繁殖植物的遗传脆弱性。
