Gene flow in, and mating system of, Rhododendron simsii in a nature reserve in subtropical China
Gene flow in, and mating system of, Rhododendron simsii in a nature reserve in subtropical China
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DOI：
10.1111/njb.01311
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发表时间：
2017-02
影响因子：
0.9
通讯作者：
C. Hahn;S. Michalski;W. Durka
中科院分区：
文献类型：
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作者：
C. Hahn;S. Michalski;W. Durka
交配系统和基因分散距离是控制物种内遗传变异分布的两个重要特征。遗传变异是适应的重要资源，但也可以深入了解物种的繁殖生物学。由于生殖生物学是特定于物种的，因此跨物种的一般推论可能不准确，并且对于许多物种来说，人们对基因流动和交配的细节知之甚少，特别是在亚热带等物种丰富的生态系统中。我们利用微卫星标记对杜鹃花的交配系统进行了表征，并确定了历史和当前的基因流距离。在中国东南部的一个近乎自然的自然保护区中对成年个体和种子进行了采样。我们检查了精细空间遗传结构（SGS）、亲缘系数、异交率和双亲近交系数。此外，我们使用亲子分析估计了花粉传播距离。我们发现高异交率和显着的双亲近交。群体分化较低，而观察到的杂合性和等位基因丰富度较高。对历史和当前基因流的估计相似，表明基因平均分散在 10 至 20 m 的距离内。亲子关系分析表明相邻个体之间频繁交配。我们得出的结论是，R. simsii 是主要的异型杂交，但不是必然的异型杂交。中等数量的双亲近交和整体低精细规模的SGS表明，相关个体之间的交配很常见，但既不会导致明显的种群分化，也不会导致相关个体的强烈聚集。最有可能的是，该物种的基因流动距离受到其开花物候的影响。大量开花、花粉/授粉媒介的限制以及种子的重力/风传播共同导致基因传播距离短。最后，种群遗传描述符表明，研究区域的 R. simsii 代表了一个庞大的、联系紧密的种群，其中保持着大量的遗传变异。
Mating system and gene dispersal distances are two important characteristics that govern the distribution of genetic variation within species. Genetic variation is an important resource for adaptation, but also allows insight into a species reproductive biology. As the reproductive biology is species specific, general inferences across species may be inaccurate and for many species not much is known about the details of gene flow and mating, especially in species-rich ecosystems such as the subtropics. We characterised the mating system and determined historical and current gene flow distances in Rhododendron simsii using microsatellite markers. Adult individuals and seeds were sampled in a near-natural nature reserve in southeast China. We examined the fine-scale spatial genetic structure (SGS), kinship coefficients, outcrossing rates and biparental inbreeding coefficients. Furthermore, we estimated pollen dispersal distances using paternity analysis. We found high outcrossing rates and significant biparental inbreeding. Population differentiation was low while observed heterozygosity and allelic richness were high. Estimates of historical and current gene flow were similar, indicating that genes are on average dispersed over distances of between 10 and 20 m. Paternity analyses suggest frequent mating among neighbouring individuals. We conclude that R. simsii is predominantly, but not obligately outcrossing. Moderate amounts of biparental inbreeding and overall low fine-scale SGS indicate that mating among related individuals is common, but does neither lead to pronounced population differentiation nor to strong aggregation of related individuals. Most likely, gene flow distances in this species are affected by its flowering phenology. Mass-flowering, pollen/pollinator limitation and gravity/wind dispersal of seeds in concert cause short gene dispersal distances. Lastly, population genetic descriptors suggest that R. simsii in the study area represents a large, well connected population in which large amounts of genetic variability are maintained.