Draga Samela, Sgorbati Sergio, Barcaccia Gianni
Laboratory of Genetics and Genomics for Plant Breeding, Department of Agronomy Food Natural Resources Animals and Environment (DAFNAE), School of Agricultural Science and Veterinary Medicine, University of Padova, 35020 Padova, Italy.
Department of Earth and Environmental Sciences, University of Milano-Bicocca, 20126 Milano, Italy.
Plants (Basel). 2025 Jan 22;14(3):321. doi: 10.3390/plants14030321.
Harms is a charismatic species discovered in the Cordillera Blanca (now Huascarán National Park, Peru) in 1867 by the great Italian-born Peruvian geographer and naturalist Antonio Raimondi. The importance of this plant is due to its imposing size, the rare and extreme ecosystem that depends on it, and the fact that it is linked to the name Antonio Raimondi. Four studies on its genetic diversity revealed a range of patterns, with a fixation index of 0.740 as weighted mean and gene flow as low as 0.02-0.03. In fact, the vast majority of the total genetic variation was documented between populations, with very low genetic variation found within populations (weighted mean genetic diversity as low as = 0.072 and mean genetic similarity very high, ranging from 96% up to 99%). We hypothesize that the narrow genetic base of populations may be due to a combination of factors: (i) an inbreeding-based reproductive strategy (i.e., mating between individuals related by common ancestry), which leads to homozygosity and genomic uniformity; (ii) strong environmental selective pressure (e.g., day-night temperature excursion, long dry period, etc.), which favors only the highest fitness individual genotypes; and (iii) a long life cycle, which hampers recombination events and reduces genetic diversity. Overall, these factors suggest that is a genetically fragile, fragmented, and endangered species.
哈姆斯是一种具有魅力的物种，1867年由伟大的意大利裔秘鲁地理学家和博物学家安东尼奥·雷蒙迪在布兰卡山脉（现秘鲁瓦斯卡兰国家公园）发现。这种植物的重要性在于其巨大的体型、依赖于它的罕见且极端的生态系统，以及它与安东尼奥·雷蒙迪这个名字的关联。四项关于其遗传多样性的研究揭示了一系列模式，加权平均固定指数为0.740，基因流低至0.02 - 0.03。事实上，总遗传变异的绝大多数记录在种群之间，种群内发现的遗传变异非常低（加权平均遗传多样性低至 = 0.072，平均遗传相似性非常高，范围从96%到99%）。我们推测种群狭窄的遗传基础可能是由于多种因素的组合：（i）基于近亲繁殖的繁殖策略（即具有共同祖先的个体之间交配），这导致纯合性和基因组一致性；（ii）强烈的环境选择压力（例如昼夜温度变化、漫长的干旱期等），这仅有利于适应性最强的个体基因型；以及（iii）长生命周期，这阻碍了重组事件并减少了遗传多样性。总体而言，这些因素表明哈姆斯是一种遗传上脆弱、碎片化且濒危的物种。
