Using partial genotyping to estimate the genetic and maternal determinants of adaptive traits in a progeny trial of Fagus sylvatica

Understanding the determinants of phenotypic variation is critical to evaluate the ability of traits to evolve in a changing environment. In trees, the genetic component of the phenotypic variance is most often estimated based on maternal progeny tests. However, the lack of knowledge about the paternal relatedness hampers the accurate estimation of additive genetic and maternal effects. Here, we investigate how different methods accounting for paternal relatedness allow the estimation of heritability and maternal determinants of adaptive traits in a natural population of Fagus sylvatica L., presenting non-random mating. Twelve potentially adaptive functional traits were measured in 60 maternal families in a nursery. We genotyped a subset of offspring and of all the potentially reproductive adults in the population at 13 microsatellite markers to infer paternal relationships and to estimate average relatedness within and between maternal families. This relatedness information was then used in family and animal models to estimate the components of phenotypic variance. All the studied traits displayed significant genetic variance and moderate heritability. Maternal effects were detected for the diameter increment, stem volume and bud burst. Comparison of family and animal models showed that unbalanced mating system led to only slight departures from maternal family assumptions in the progeny trial. However, neglecting the significant maternal effects led to an overestimation of the heritability. Overall, we highlighted the usefulness of relatedness pattern analyses using polymorphic molecular markers to accurately analyse tree sibling designs.解析表型变异的决定因素，对于评估性状在变化环境中的演化能力至关重要。在林木研究中，表型方差的遗传组分通常基于母本子代试验进行估算。然而，由于对父本亲缘关系的认知不足，准确估算加性遗传效应与母本效应的工作受到了阻碍。本研究以存在非随机交配的天然欧洲山毛榉（Fagus sylvatica L.）种群为对象，探讨了不同考虑父本亲缘关系的方法如何实现适应性性状的遗传力与母本决定因素的估算。我们在苗圃中对60个母本家系的12个潜在适应性功能性状开展了测定。针对种群中的部分子代以及所有潜在繁殖成年个体，我们利用13个微卫星（microsatellite）标记进行基因分型，以推断父本亲缘关系并估算母本家系内部及家系间的平均亲缘系数。随后，我们将该亲缘关系信息应用于家系模型与动物模型，以估算表型方差的组分。所有研究性状均表现出显著的遗传方差与中等水平的遗传力。针对直径生长量、茎干体积与芽萌动性状，我们检测到了显著的母本效应。家系模型与动物模型的对比结果显示，不平衡的交配系统仅导致子代试验中母本家系假设出现轻微偏离。然而，若忽略显著的母本效应，则会导致遗传力的高估。总体而言，本研究证实了利用多态性分子标记开展亲缘关系模式分析，可准确解析林木同胞设计的相关问题。