An allelic series at pax7a is associated with colour polymorphism diversity in Lake Malawi cichlid fish.
An allelic series at pax7a is associated with colour polymorphism diversity in Lake Malawi cichlid fish.
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DOI：
10.1111/mec.13975
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发表时间：
2017-05
影响因子：
4.9
通讯作者：
Kocher TD
中科院分区：
文献类型：
--
作者：
Roberts RB;Moore EC;Kocher TD
尽管人们长期以来对离散表型多态性的进化和维持感兴趣，但这种多态性在野外的分子遗传基础在很大程度上是未知的。在东非马拉维湖慈鲷中发现的与雌性相关的斑点颜色多态性代表了一种非常成功的多态性表型，在整个湖区的四个属中发现并维持。此前，我们在马拉维湖慈鲷中发现了配对盒转录因子基因 pax7a 的等位基因变体与斑点颜色变形之间的关联。尽管马拉维湖慈鲷物种中存在多种斑点表型，但它们似乎都是由 pax7a 等位基因产生的，该等位基因产生更高水平的转录本。在这里，我们研究了斑点形态变异的发育和遗传基础。首先，我们确认 pax7a 相关的斑点变形主要是由于黑素细胞发育和存活的调节所致。通过实验室杂交和自然群体研究，除了祖先的 pax7a 等位基因之外，我们还鉴定出至少三个与斑点变体的离散亚型相关的 pax7a 等位基因。 pax7a 的基因型支持新的 pax7a 等位基因的初始进化以产生斑点类型的变形，随后该 pax7a 斑点等位基因的后续进化以产生与离散颜色变形相关的其他等位基因。 pax7a 的变异等位基因产生不同水平的 pax7a 转录物，与细胞水平的色素沉着表型相关。这个自然选择的等位基因系列应该作为了解 pax7a 表达的分子遗传控制和性别相关等位基因进化的案例研究。
Despite longstanding interest in the evolution and maintenance of discrete phenotypic polymorphisms, the molecular genetic basis of such polymorphism in the wild is largely unknown. Female sex-associated blotched color polymorphisms found in cichlids of Lake Malawi, East Africa represent a highly successful polymorphic phenotype, found and maintained in four genera across the geographic expanse of the lake. Previously, we identified an association with an allelic variant of the paired-box transcription factor gene pax7a and blotched color morphs in Lake Malawi cichlid fishes. Though a diverse range of blotched phenotypes are present in Lake Malawi cichlid species, they all appeared to result from an allele of pax7a that produces increased levels of transcript. Here, we examine the developmental and genetic basis of variation among blotched morphs. First, we confirm that pax7a-associated blotch morphs result primarily from modulation of melanophore development and survival. From lab crosses and natural population studies, we identify at least three alleles of pax7a associated with discrete subtypes of blotched morphs, in addition to the ancestral pax7a allele. Genotypes at pax7a support initial evolution of a novel pax7a allele to produce the blotched class of morphs, followed by subsequent evolution of that pax7a blotched allele to produce additional alleles associated with discrete color morphs. Variant alleles of pax7a produce different levels of pax7a transcript, correlating with pigmentation phenotype at the cellular level. This naturally selected allelic series should serve as a case study for understanding the molecular genetic control of pax7a expression and the evolution of sex-associated alleles.