Patterns of genetic variation around a locus under strong selection in wild Heliconius populations

所有动植物的野生种群在许多特征上都不同，这些特征由遗传变异控制。在野生种群中寻找控制自然变异的基因是一个重大挑战，在应用科学和基础科学中都很重要。进化生物学家感兴趣的是控制动植物多样性和适应的基因是什么，而应用生物学家想要识别与重要经济性状有关的基因，如农作物的抗病或害虫及其近亲的抗药性。在这里，我们将研究进化生物学中的一个经典系统--热带赫利柯乌斯蝴蝶的模仿翅膀模式。我们将使用现代分子技术来研究控制蝴蝶Helconius Melpomene模拟模式的地理变异的遗传位点以及密切相关的物种Helconius Numata的种群内模拟多态。通过模仿，不同的经过化学防御的猎物分享警告颜色，这是一种生态学上很好理解的适应性特征，可以选择在当地猎物群落内趋同。拟态等位基因在同一物种的种群之间和种群内有所不同，并参与物种形成。Numata中的P基因座与H.Melpomene中的N-Yb-Sb基因座位于同一基因组区域。将在包含模仿位点的区域中存在的所有基因中生成标记。然后将在野生种群中筛选变异，以寻找与蝴蝶的模式表型相关的变异。例如，如果A和G在特定的基因座上发生了多态性，我们将调查具有特定翅膀图案的蝴蝶是否有一种趋势，即A或G的频率随机高于预期。我们将使用高通量、高性价比的基因技术，准确地估计每个可变标记与颜色模式的关联。这项工作将进一步定位该区域，并可能识别导致巨大形态变化和适应当地猎物群落的基因。在H.Melpomene中，任何特定地点的所有个体都有相同的翅膀模式，我们将调查是否有一个区域显示出较少的变异或较高频率的稀有变异，这两个区域都暗示了最近自然选择对某个基因座的作用。黑斑潜蝇小种的范围范围变化很快，因此我们的工作将为深入了解快速适应范围扩展对相关遗传变异的影响提供依据。

Wild populations of all plants and animals vary in many traits that are controlled by genetic variation. Finding the genes that control natural variation in wild populations is a major challenge, important in both applied and basic science. Evolutionary biologists are interested to know what the genes are that control diversity and adaptation in animals and plants, while applied biologists would like to identify genes involved in economically important traits such as disease resistance in crops or insecticide resistance in pests and their relatives. Here we will study a classic system in evolutionary biology, the mimetic wing patterns of tropical Heliconius butterflies. We will use modern molecular techniques to investigate a genetic locus that controls a geographic variation in mimetic pattern in the butterfly Heliconius melpomene and a within-population mimetic polymorphism in the closely-related species Heliconius numata. Mimicry, by which different chemically-defended prey share warning colours, is an ecologically well-understood adaptive trait with selection for convergence within the local prey community. Mimicry alleles vary between and within populations of the same species and are involved in speciation. The P locus in H. numata is found in the same genome region as the N-Yb-Sb locus in H. melpomene. Markers will be generated within all genes present across the region containing the mimicry locus. Variation will then be screened in wild populations of H. numata in order to search for variants that are associated with the pattern phenotype of the butterflies. For example, if a polymorphism occurs between an A and a G at a particular locus, we will investigate whether there is a tendency for the butterflies with a particular wing pattern to have either A or G at a higher frequency than expected at random. We will use high throughput, cost-effective genetic techniques that accurately estimate the association of each variable marker with colour pattern. This work will further localize the region, and possibly identify the gene, that is responsible for dramatic morphological variation and adaptation to local prey communities. In H. melpomene, where all individuals in any particular locality have the same wing pattern, we will investigate whether there is a region that shows reduced variation or a high frequency of rare variants, both of which are suggestive of the recent action of natural selection on a locus. The range margins of H. melpomene races change rapidly, so our work will provide insight into the effect of rapid adaptive range expansion on associated genetic variation.