Heterogeneity of genetic architecture of body size traits in a free-living population

Knowledge of the underlying genetic architecture of quantitative traits could aid in understanding how they evolve. In wild populations, it is still largely unknown whether complex traits are polygenic or influenced by few loci with major effect, due to often small sample sizes and low resolution of marker panels. Here, we examine the genetic architecture of five adult body size traits in a free-living population of Soay sheep on St Kilda using 37 037 polymorphic SNPs. Two traits (jaw and weight) show classical signs of a polygenic trait: the proportion of variance explained by a chromosome was proportional to its length, multiple chromosomes and genomic regions explained significant amounts of phenotypic variance, but no SNPs were associated with trait variance when using GWAS. In comparison, genetic variance for leg length traits (foreleg, hindleg and metacarpal) was disproportionately explained by two SNPs on chromosomes 16 (s23172.1) and 19 (s74894.1), which each explained >10% o...

解析数量性状的潜在遗传架构，有助于理解其演化机制。在野生种群中，由于样本量通常较小且标记面板分辨率较低，学界仍未明确复杂性状究竟属于多基因调控，还是受少数主效位点影响。本研究基于圣基尔达（St Kilda）群岛自由栖息的索艾羊（Soay sheep）野生种群，利用37037个多态性单核苷酸多态性（single nucleotide polymorphism, SNP）标记，解析了5种成体体型性状的遗传架构。其中两项性状（颌骨长度与体重）表现出多基因性状的典型特征：染色体解释的方差比例与其长度呈正相关，多条染色体及多个基因组区域可解释显著表型方差，但通过全基因组关联分析（genome-wide association study, GWAS）未检测到与性状方差相关的SNP。相较而言，腿长相关性状（前腿长、后腿长及掌骨长）的遗传方差则主要由16号染色体上的s23172.1与19号染色体上的s74894.1两个SNP解释，每个位点均能解释>10% o...