Small populations have genetic attributes that make them prone to extinction, including low effective population size (Ne), increased levels of inbreeding, and negative impacts from genetic drift. Some small populations are also clonal with low levels of genetic diversity, restricted seed dispersal, and high levels of genetic structure. Together, these attributes make species with small, isolated, clonal populations unlikely to persist under environmental change. We investigated an endangered woody plant species (Persoonia hindii) in eastern Australia to answer key questions about genetic differentiation, migration rates, population sizes, size of clones, mating system and Ne. We identified 587 single nucleotide polymorphisms. Of the 88 individual stems collected from 15 sites across the entire distribution of P. hindii, we identified 30 multi-locus genotypes (MLG). Additional fine-scale genotyping of two sites (49 and 47 stems) detected a dominant genet within each site occupying a minimum area of 20 m2. Global population differentiation was high (FST 0.22) with very low migration rates (0.048 - 0.064). We identified some population structure with variable site pairwise differentiation (0.015 - 0.32) with no detectable spatial autocorrelation. Species wide inbreeding coefficient was 0.42 (FIT), supporting the direct estimate of 82% selfing. Estimated Ne was extremely small (15), indicating that genetic drift may be reducing genetic diversity and increasing genetic load through fixation of deleterious alleles. Clonality and inbreeding combined with negligible gene flow suggests limited adaptive capacity to respond to climate challenges. Genetic rescue, through assisted gene migration and experimental translocations, would enhance the persistence of natural populations.

中文翻译：

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克隆和近亲繁殖会放大一种稀有的山地木本植物（Persoonia hindii； Proteaceae）的遗传隔离和交配限制

小种群具有使其容易灭绝的遗传属性，包括有效种群数量低（Ne），近交水平增加以及遗传漂移带来的负面影响。一些小种群也具有较低的遗传多样性，有限的种子传播和较高的遗传结构克隆。综合起来，这些属性使得具有较小，孤立的克隆种群的物种不太可能在环境变化下持续存在。我们调查了澳大利亚东部濒临灭绝的木本植物物种（Persoonia hindii），以回答有关遗传分化，迁移率，种群大小，克隆大小，交配系统和Ne的关键问题。我们确定了587个单核苷酸多态性。从印度假单胞菌整个分布的15个部位收集的88个单个茎中，我们确定了30个多基因座基因型（MLG）。对两个位点（49和47个茎）进行的额外精细基因分型，检测到每个位点内的优势种至少占据20平方米。全球人口分化程度很高（FST 0.22），迁徙率非常低（0.048-0.064）。我们确定了一些具有可变位点成对分化（0.015-0.32）且没有可检测到的空间自相关的种群结构。物种的近交系数为0.42（FIT），支持直接估计82％的自交。估计的Ne极小（15），表明遗传漂移可能通过固定有害等位基因而降低了遗传多样性并增加了遗传负荷。克隆性和近交与可忽略的基因流相结合表明应对气候挑战的适应能力有限。基因拯救