The prevalence of genetic introgression in speciation

背景：物种间遗传交换的重要性(即从一个物种导入基因 物种通过杂交中间体转移到另一个物种)是进化论中不断争论的主题 生物学家。虽然一些人声称基因交换无处不在，但另一些人则声称这种情况极其罕见。目前， 从数量上支持这两种情况的数据很少。 广泛的、长期的目标：拟议的对自然形成的混合区的研究将量化 物种间遗传交流的普遍程度，以了解其频率和进化后果 基因交换。该提案利用这些在混合区的自然实验来寻找混合体 基因组，我可以用它来描绘不同于杂交的复杂行为特征的遗传学 物种。由于行为特征的遗传图谱通过传统方法被证明是非常困难的，所以混合 测绘为在这些重要问题上取得进展提供了一个独特的机会。 具体目标：研究的目标1是绘制六个自然杂交区的渗入盛行率图，其中四个 它们是第一次在这里被记录下来。Aim 2将使用来自杂交区域的混合苍蝇来绘制基因图谱 这是温度偏好这一重要的生态特征的基础。目标3将使用来自另一家公司的混合苍蝇 杂交区，以定位配偶偏好复杂行为特征的潜在基因。 方法：果蝇属的果蝇可以在它们的自然栖息地收集并维护 在实验室条件下，拥有无与伦比的分子遗传和基因组工具。这 Proposal提出了一种新的模型来识别基因组中的导入等位基因，这种方法只是 在亲本物种都有高质量基因组组合的杂交生物中是可行的。这个 在这些混合分析中确定的基因将通过CRISPR介导的基因进行功能验证 接班人。混合作图和基因组编辑的初步结果都很有希望。 与健康相关：在人类中混合标测是用于识别 致病基因变异。然而，后续实验要测试与之相关的基因的功能 疾病不能在人类身上发生。因此，混合映射协议从未得到验证 端到端，从识别与疾病相关的变异的种群水平，到功能 表现出表型状态的分子遗传水平。这项建议具有创新性，因为它 开发新的计算方法来识别具有复杂祖先的基因组区域，然后连接 通过基因组编辑将这些基因组模式转换为可测量的表型差异。 影响：这项研究的结果将提供第一个广泛的观点，在以下情况下的内向模式 物种在自然界中杂交，并将利用这些混合模式来剖析 导致生殖隔离的物种之间的行为差异。

Background: The importance of genetic exchange between species (i.e. introgression of genes from one species into another through hybrid intermediates) is a constant subject of debate among evolutionary biologists. While some claim genetic exchange is pervasive, others claim that it is extremely rare. Currently, there is little data quantitatively supporting either of these scenarios. Broad, long-term objective: The proposed study of naturally occurring hybrid zones will quantify the prevalence of genetic exchange between species to understand the frequency and evolutionary consequences of gene exchange. The proposal takes advantage of these natural experiments in hybrid zones to find admixed genomes with which I can map the genetics of complex behavior traits that differ between the hybridizing species. Since genetic mapping of behavior traits has proven very difficult by conventional means, admixture mapping provides a unique opportunity to make progress on these important questions. Specific aims: Aim 1 of the study is to map the prevalence of introgression in six natural hybrid zones, four of which are documented here for the first time. Aim 2 will used admixed flies from a hybrid zone to map genes underlying the ecologically important trait of temperature preference. Aim 3 will use admixed flies from another hybrid zone to map genes underlying the complex behavioral trait of mate preference. Method: Fruit flies from the genus Drosophila can be collected in their natural habitat and also maintained under laboratory conditions, and have an unmatched arsenal of molecular genetic and genomic tools. This proposal presents a novel model for identifying introgressed alleles in the genome, an approach that is only feasible in hybridizing organisms for which both parental species have high quality genome assemblies. The genes identified in these admixture analyses will be functionally validated with CRISPR-mediated gene replacements. Preliminary results for admixture mapping and genome editing are both promising. Health-relatedness: Admixture mapping in humans is a primary approach used for the identification of disease-causing gene variants. However, follow up experiments to test the function of genes correlated with disease cannot be performed in humans. Admixture mapping protocols have therefore never been validated end-to-end from the population level at which variants correlated with disease are identified, to the functional molecular genetic level where the phenotypic state is manifested. This proposal is innovative because it develops new computational methods to identify genomic regions with complex ancestry, and then connects these genomic patterns to measurable phenotypic differences via genome editing. Impact: The results from this study will provide the first broad view of patterns of introgression in cases where species interbreed in nature, and will leverage those patterns of admixture to dissect the genetic basis of behavioral differences between species that cause reproductive isolation.