Data from: Admixture mapping of quantitative traits in Populus hybrid zones: power and limitations

Uncovering the genetic architecture of species differences is of central importance for understanding the origin and maintenance of biological diversity. Admixture mapping can be used to identify the number and effect sizes of genes that contribute to the divergence of ecologically important traits, even in taxa that are not amenable to laboratory crosses due to their long generation time or other limitations. Here, we apply admixture mapping to naturally occurring hybrids between two ecologically divergent Populus species. We map quantitative trait loci (QTL) for eight leaf morphological traits using 77 mapped microsatellite markers from all 19 chromosomes of Populus. We apply multivariate linear regression analysis allowing the modeling of additive and non-additive gene action and identify several candidate genomic regions associated with leaf morphology using an information-theoretic approach. We perform simulation studies to assess the power and limitations of admixture mapping of quantitative traits in natural hybrid populations for a variety of genetic architectures and modes of gene action. Our results indicate that (1) admixture mapping has considerable power to identify the genetic architecture of species differences if sample sizes and marker densities are sufficiently high, (2) modeling of non-additive gene action can help to elucidate the discrepancy between genotype and phenotype sometimes seen in interspecific hybrids, and (3) the genetic architecture of leaf morphological traits in the studied Populus species involves complementary and overdominant gene action, providing the basis for rapid adaptation of these ecologically important forest trees.

揭示物种差异的遗传结构，对于理解生物多样性的起源与维持具有核心意义。渐渗作图（admixture mapping）可用于鉴定调控生态重要性状分化的基因数量与效应大小，即便针对那些因世代周期较长或其他限制而无法开展实验室杂交的类群，该方法依然适用。本研究将渐渗作图应用于两个生态分化杨属（Populus）物种的天然杂种群体。我们依托覆盖杨属全部19条染色体的77个已定位微卫星标记，对8个叶片形态性状开展数量性状位点（quantitative trait loci, QTL）定位分析。我们采用支持加性与非加性基因作用建模的多元线性回归分析方法，并结合信息论方法，鉴定出多个与叶片形态相关的候选基因组区域。我们通过模拟研究，评估了在多种遗传结构与基因作用模式下，对自然杂种群体的数量性状开展渐渗作图的效力与局限性。本研究结果显示：（1）若样本量与标记密度足够高，渐渗作图可有效鉴定物种差异的遗传结构；（2）对非加性基因作用进行建模，有助于阐明种间杂种中偶尔出现的基因型与表型间的不一致现象；（3）所研究杨属物种的叶片形态性状遗传结构涉及互补与超显性基因作用，为这类具有重要生态价值的林木的快速适应性演化提供了理论依据。