Genetic mapping of the Midas cichlid GOLD locus

自达尔文以来，新物种如何出现的问题一直是进化生物学研究的中心。尽管物种形成的遗传学引起了广泛的兴趣，但到目前为止，只发现了少数几个有助于物种隔离的基因。慈鱼是已知物种形成速度最快的鱼类，因此是研究物种形成的理想模式生物。最近发现，在没有地理隔离的情况下，中美洲的迈达斯鱼科动物通过生态专门化和基于颜色的分类交配而发生了分化。一些物种有两种颜色形态：正常(也称为“条状”或“深色”)和“金色”。金鱼和北极鱼根据颜色选择配偶，它们非常喜欢自己颜色的配偶，而不是颜色不同的个体。然而，关于颜色差异的遗传基础，特别是对颜色的交配偏好，几乎一无所知。对这些重要表型差异的遗传基础的了解对于更深入地理解这种着色差异是如何进化的以及它如何促进物种形成至关重要。这些鱼的色素差异的原因也将为人类色素沉着障碍的遗传学提供洞察力，因为所有的鱼一开始都是黑色的形态，只有遗传上有黄金的个体在以后的生活中才会失去他们的黑色素载体。我的实验室以前的结果表明，金色表型是显性的，可能是由于单个基因所致。我们已经将其映射到一个只包含大约10到15个基因的基因组区域。利用最新的技术和方法发展，该项目的目的是在位置上精细定位，鉴定并从功能上验证导致水母金色的基因/突变(S)--这是一种与新物种起源有关的基因。

The question of how new species arise has been at the centre of evolutionary biological research ever since Darwin. Despite widespread interest in the genetics of speciation, only a handful of genes that contribute to species isolation have been discovered so far. Cichlid fishes have the fastest known rate of speciation and therefore are well-suited model organisms for the study of speciation. The Midas cichlids of Central America were recently shown to have diverged in the absence of geographic isolation through ecological specialization and by colour-based assortative mating. Several species come in two colour morphs: normal (also called "barred" or "dark") and "gold". Gold and nornial fish choose mates based on colour and very strongly prefer mates of their own colour over individuals with a different colouration. However, virtually nothing is known about the genetic basis of the colour differences and especially, the mating preference for colour. Knowledge about the genetic bases of these important phenotypic differences is crucial for a deeper understanding of how this difference in colouration has evolved and how it promotes speciation. The cause of pigmentation differences in these fish will also provide insights into the genetics of human pigmentation disorders since all fish start out as "dark" morphs and only the genetically gold individuals lose their melanophores later in life. Previous results from my laboratory show that the gold phenotype is dominant and is likely due to a single gene. We have mapped it already to a genomic region that contains only about 10 to 15 genes. Taking advantage of recent technological and methodological developments, this project aims to positionally fine-map,p identify and functionally validate the gene/mutation(s) responsible for the gold colour in the Midas cichlid - a gene that is involved in the origin of new species.