Oliva Silvia, Romero Javier, Pérez Marta, Manent Pablo, Mascaró Oriol, Serrão Ester A, Coelho Nelson, Alberto Filipe
Departament d'Ecologia, Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain; Dipartimento di Scienze della Natura e del Territorio, Università degli Studi di Sassari, Via Piandanna 4, Sassari, 07100, Italy.
Mol Ecol. 2014 Dec;23(23):5698-711. doi: 10.1111/mec.12973. Epub 2014 Nov 15.
Genetic diversity in clonal organisms includes two distinct components, (i) the diversity of genotypes or clones (i.e. genotypic richness) in a population and (ii) that of the alleles (i.e. allelic and gene diversity within populations, and differentiation between populations). We investigated how population differentiation and genotypic components are associated across a gradient of eutrophication in a clonal marine plant. To that end, we combined direct measurements of sexual allocation (i.e. flower and seed counts) and genotypic analyses, which are used as an estimator of effective sexual reproduction across multiple generations. Genetic differentiation across sites was also modelled according to a hypothesis here defined as isolation-by-demography, in which we use population-specific factors, genotypic richness and eutrophication that are hypothesized to affect the source-sink dynamics and thus influence the genetic differentiation between a pair of populations. Eutrophic populations exhibited lower genotypic richness, in agreement with lower direct measurements of sexual allocation and contemporaneous gene flow. Genetic differentiation, while not explained by distance, was best predicted by genotypic richness and habitat quality. A multiple regression model using these two predictors was considered the best model (R(2) = 0.43). In this study, the relationship between environment and effective sexual-asexual balance is not simply (linearly) predicted by direct measurements of sexual allocation. Our results indicate that population-specific factors and the isolation-by-demography model should be used more often to understand genetic differentiation.
（i）一个种群中基因型或克隆的多样性（即基因型丰富度），以及（ii）等位基因的多样性（即种群内的等位基因和基因多样性，以及种群间的分化）。我们研究了在一种克隆海洋植物中，沿着富营养化梯度，种群分化和基因型组成是如何关联的。为此，我们将性分配的直接测量（即花和种子计数）与基因型分析相结合，后者被用作多代有效有性繁殖的估计指标。跨地点的遗传分化也根据这里定义为“人口统计学隔离”的假设进行建模，在该假设中，我们使用特定于种群的因素、基因型丰富度和富营养化，这些因素被假设会影响源 - 汇动态，从而影响一对种群之间的遗传分化。富营养化种群表现出较低的基因型丰富度，这与较低的性分配直接测量值和同期基因流一致。遗传分化虽然不能用距离来解释，但最好由基因型丰富度和栖息地质量来预测。使用这两个预测变量的多元回归模型被认为是最佳模型（R² = 0.43）。在本研究中，环境与有效的有性 - 无性平衡之间的关系并非简单地（线性地）由性分配的直接测量来预测。我们的结果表明，应更频繁地使用特定于种群的因素和人口统计学隔离模型来理解遗传分化。
