Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom.
Evolution. 2013 May;67(5):1251-62. doi: 10.1111/evo.12060. Epub 2013 Feb 28.
Quantitative trait locus (QTL) mapping is frequently used in evolutionary studies to understand the genetic architecture of continuously varying traits. The majority of studies have been conducted in specially created crosses, in which genetic differences between parental lines are identified by linkage analysis. Detecting QTL segregating within populations is more problematic, especially in wild populations, because these populations typically have complicated and unbalanced multigenerational pedigrees. However, QTL mapping can still be conducted in such populations using a variance components mixed model approach, and the advent of appropriate statistical frameworks and better genotyping methods mean that the approach is gaining popularity. In this study it is shown that all studies described to date report evidence of QTL of major effect on trait variation, but that these findings are probably caused by inflated estimates of QTL effect sizes due to the Beavis effect. Using simulations I show that even the most powerful studies conducted to date are likely to give misleading descriptions of the genetic architecture of a trait. I show that an interpretation of a mapping study of beak color in the zebra finch (Taeniopygia guttata), that suggested genetic variation was determined by a small number of loci of large effect, which are possibly maintained by antagonistic pleiotropy, is likely to be incorrect. More generally, recommendations are made to how QTL mapping can be combined with other approaches to provide more accurate descriptions of a trait's genetic architecture.
数量性状位点（QTL）作图常用于进化研究，以了解连续变异性状的遗传结构。大多数研究都是在特别设计的杂交中进行的，通过连锁分析确定亲本系之间的遗传差异。在种群中检测分离的 QTL 更成问题，特别是在野生种群中，因为这些种群通常具有复杂且不平衡的多代系谱。然而，使用方差分量混合模型方法仍然可以在这些种群中进行 QTL 作图，并且适当的统计框架和更好的基因分型方法的出现意味着这种方法越来越受欢迎。在这项研究中表明，迄今为止所有描述的研究都报告了对性状变异的主要效应 QTL 的证据，但由于 Beavis 效应，这些发现可能是由于 QTL 效应大小的估计膨胀引起的。通过模拟，我表明即使是迄今为止进行的最强大的研究，也可能对性状的遗传结构产生误导性描述。我表明，对斑胸草雀（Taeniopygia guttata）喙色的作图研究的解释，表明遗传变异是由少数几个大效应的基因座决定的，这些基因座可能是由拮抗多效性维持的，这可能是不正确的。更一般地，提出了如何将 QTL 作图与其他方法相结合，以更准确地描述性状的遗传结构的建议。
