The genomic architecture of convergent snail crushing jaws in cichlid fishes

在适应性辐射期间出现的趋同表型通常可能是由基因组结构的类似变化引起的。本提案的目的是测试假设关于收敛的基因组结构破碎咽形态在几个谱系的慈鲷鱼。概述的方法整合了基因组区域的位置映射，影响基因组内的特征，如牙齿大小，肌肉质量和下颌缝合。该提案解决了三个主要问题：目标1：哪些基因组区域与H. minckleyi人的牙齿大小多态性相关？利用杂交F2定位杂交，我们将确定是否存在一个大影响位点或基因组的多个区域与H. minckleyi的咽齿双峰大小相关。目的2：野生minckleyi H.与牙齿大小多态性相关的其他咽颌性状的QTL是否与牙齿大小QTL共定位？我们将使用目标1中鉴定的QTL来确定与臼齿形和乳头状牙齿大小二分法相关的其他咽颌性状鉴定的QTL是否共定位于存在牙齿大小QTL的基因组同源区域。我们还将评估这些附加性状的基因组结构本身是否异常地共定位于基因组的相似区域。目的3：基因组结构是否与其他慈鲷谱系中的破碎表型相关？我们将使用另外四个沿molariform到papilliform轴不同的物种杂交，以确定跨越慈鲷多样性的物种对是否表现出相同数量的QTL，相同程度的共定位，以及我们在H. minckleyi多态群体中恢复的喉颌分化同源基因组位置的QTL。在沿相似表型轴分化的许多谱系中进行的QTL研究应提供一种测试，以确定相似或非常不同的基因组位点是否在种群内和不同种类的慈鲷鱼类中产生咽颌趋同。

Convergent phenotypes that arise during adaptive radiation could often result from similar changes in genomic architecture. The goal of this proposal is to test hypotheses regarding the genomic architecture of convergence in crushing pharyngeal morphology in several lineages of cichlid fish. The outlined approach integrates mapping of the position of genomic regions affecting traits such as tooth size, muscle mass, and jaw suturing within the genome. The proposal addresses three major questions:Objective 1: What genomic region(s) are associated with the polymorphism in tooth size found in H. minckleyi? Using a hybrid F2 mapping cross, we will determine if there is a single locus of large effect or alternatively multiple regions of the genome associated with bimodal size of the pharyngeal teeth in H. minckleyi. Objective 2: Do the QTL for other pharyngeal jaw traits associated with the tooth size polymorphism in wild-caught H. minckleyi co-localize to tooth size QTL? We will use the QTL identified in Objective 1 to determine if QTL identified for other pharyngeal jaw traits associated with the molariform versus papilliform tooth size dichotomy co-localize to homologous regions of the genome where tooth size QTL(s) are present. We will also evaluate whether the genomic architecture for these additional traits themselves are exceptionally co-localized to similar regions of the genome.Objective 3: Is the genomic architecture associated with the crushing phenotypes in other cichlid lineages similar to that found in H. minckleyi? We will use four additional hybrid crosses of species that differ along a molariform to papilliform axis to determine if species pairs that span cichlid diversity exhibit the same number of QTLs, same degree of co-localization, as well as QTL in the homologous genomic locations that we recovered for the pharyngeal jaw divergence in polymorphic populations of H. minckleyi.The QTL studies performed in a number of lineages that have diverged along a similar phenotypic axis should provide a test of whether similar or very distinct genomic loci have generated pharyngeal jaw convergence within populations and across species of cichlid fishes.