The molecular causes of convergent evolution

1)大问题趋同进化是对相似表型重复进化的自然实验，为进化过程提供了独特的见解。当相似的模式在不同的谱系中进化时，相同的分子机制在多大程度上被部署？相同的调控变化是否会产生趋同的表型？在快速进化过程中，单个位点的进化变化如何调节复杂的模式变化？新的发育模式的进化需要哪些精确的遗传变化？Heliconius蝴蝶是解决这些问题的一个很好的系统。2）背景许多热带蝴蝶都有模仿的翅膀图案来警告捕食者它们的毒性，这些已经成为一个很好的系统，在其中理解聚合和多样化的分子基础，并在野生自然选择和基因组进化之间建立联系。在这里，我们将研究热带Heliconius蝴蝶模式收敛的分子基础。遗传作图和基因表达实验已经确定了一个简单的系统的三个遗传基因座，控制复杂的多样化翅膀图案中看到的Heliconius。其中一个基因座调节黄色图案元素，相同的基因组基因座也参与了胡椒蛾、桦褐蝶和蝴蝶的翅膀图案形成，这表明蝴蝶和蛾中存在一个古老的共享图案形成系统。来自自然种群的表达模式和遗传数据表明，皮质是该位点的功能基因，尽管表达数据也指向其他相关基因的参与。我们将应用最近开发的CRISPR/Cas9基因敲除方法来研究Heliconius蝴蝶物种之间模式收敛的分子基础。3)目的和预期结果我们将测试在模仿蝴蝶中使用相同基因进化相似模式的频率。在更近的分辨率下，我们还将测试这些基因是否由相同的调节开关控制，当它们控制相似的模式时，打开和关闭它们。这将测试不同遗传背景下进化的可重复性。这些实验将涉及开发和应用新的基因编辑技术来研究这些蝴蝶的模式，这将为未来的进化研究制定标准。长期以来，这些蝴蝶的模仿模式一直被认为是自然选择进化的典范，这个项目将为在许多不同物种中产生如此惊人相似模式的分子机制提供独特的新见解。

1) The big questionsConvergent evolution is a natural experiment in repeated evolution of similar phenotypes, offering unique insights into the evolutionary process. When similar patterns evolve in different lineages, to what extent are the same molecular mechanisms deployed? Are the same regulatory changes co-opted into generating convergent phenotypes? How can evolutionary change at a single locus regulate complex patterning changes during rapid evolution? What are the precise genetic changes necessary for the evolution of a new developmental pattern? Heliconius butterflies are an excellent system to address these questions.2) The backgroundMany tropical butterflies have mimetic wing patterns to warn predators of their toxicity, and these have become an excellent system in which to understand the molecular basis for convergence and diversification, and make the link between natural selection in the wild and evolution in the genome. Here we will study the molecular basis for pattern convergence in tropical Heliconius butterflies. Genetic mapping and gene expression experiments have identified a simple system of three genetic loci that control the complex diversification in wing patterning seen in Heliconius. One of these loci regulates yellow pattern elements and the same genomic locus is also involved in wing patterning of both the peppered moth, Biston betularia, and the butterfly Bicyclus anynana, suggesting an ancient shared patterning system in butterflies and moths. Patterns of expression and genetic data from natural populations, suggest that cortex is the functional gene at this locus, although expression data also point to involvement of other linked genes. We will apply recently developed CRISPR/Cas9 methods for gene knockouts to investigate the molecular basis for pattern convergence between species of Heliconius butterflies. 3) Objectives and expected resultsWe will test the frequency with which similar patterns evolving in mimetic butterflies use the same genes. At a closer resolution, we will also test whether those genes are controlled by the same regulatory switches to turn them on and off, when they control similar patterns. This will test for the repeatability of evolution in different genetic backgrounds. These experiments will involve developing and applying novel gene editing techniques to study patterning in these butterflies, which will set the standard for evolutionary studies in the future. The remarkable patterns of mimicry in these butterflies have long been considered an exemplar of evolution by natural selection, and this project will offer unique new insights into the molecular mechanisms that produce such strikingly similar patterns in so many different species.