Dissecting the molecular basis and assembly of a complex morphological trait

 描述（由申请人提供）： 本研究的目的是剖析一个复杂性状的致病基因和突变，并跟踪确定的致病等位基因出现和传播通过一个孤立的群体，以产生一个固定的形态表型的逐步过程。果蝇（Drosophila santomea）的色素模式最近发生了巨大的变化，这是一个最佳的模型系统，可以用来分析复杂的多基因性状。我们以前的工作确定了四个主要QTL之一的基因有助于这一性状。对群体中多个个体的分析表明，该基因的致病等位基因在D. santomea人口（即“软扫描”）。在这里，我们建议采用分子遗传技术（渐渗作图和转基因互补），以确定致病基因和突变负责两个额外的QTL。使用分子和基因组技术（原位杂交，RNA-seq）的组合，我们将评估这些位点如何相互作用，以及它们如何影响全基因组表达谱。最后，我们将调查这些额外的致病基因座的群体变异，以评估是否发生了类似的软扫描，并确定这些基因是否表现出正选择的迹象。这项研究将提供一个复杂的形态特征，整合基因功能的分子研究与过程发生在人口水平上的罕见远景。

 DESCRIPTION (provided by applicant): The goal of this research is to dissect the causative genes and mutations underlying a complex trait, and trace the stepwise process by which the identified causative alleles arose and spread through an isolated population to generate a fixed morphological phenotype. The species Drosophila santomea exhibits a recently evolved, drastic shift in its pigment patterns that represents an optimal model system in which to dissect complex polygenic traits. Our previous work identified the gene underlying one of four major QTL contributing to this trait. Analysis of multiple individuals in the population revealed that causative alleles of this gene arose several times in parallel in the D. santomea population (i.e. a "soft sweep"). Here, we propose to employ molecular genetic techniques (introgression mapping and transgenic complementation) to identify causative genes and mutations responsible for two additional QTL. Using a combination of molecular and genomic techniques (in situ hybridization, RNA-seq), we will then assess how these loci interact with each other, as well as how they impact the genome-wide profile of expression. Finally, we will survey population variation at these additional causative loci to assess whether a similar soft sweep occurred, and determine whether these genes exhibit signs of positive selection. This study will provide a rare vista of a complex morphological trait that integrates molecular studies of gene function with processes occurring at the population level.