An experimental test of hybrid speciation

摘要/项目摘要 背景：杂交物种形成--当杂交后代从其亲本物种中繁殖分离出来时--是 据说在植物中很常见，但这一过程在动物中的重要性却引起了激烈的争论。困难之处在于 获得动物杂交物种形成的证据导致了物种形成研究中的两个阵营：那些声称 在动物中，这种杂交物种的形成是罕见的，那些认为这一过程非常猖獗的人。答案是 必然位于这两个极端之间的某个地方，但还没有尝试过实验测试。 广泛的、长期的目标：我的研究目标是使用精心设计的实验来了解 不同物种形成机制的重要性。可以说，杂交物种形成仍然是最有争议的 所有产生新血统的进化过程。果蝇是研究的首要动物系统 实验物种形成，在这项提议中，我利用它的力量来评估杂交物种形成的重要性。 具体目标：这个项目的目标是了解新的动物物种通过 杂交。目标1将在35对具有不同遗传水平的物种之间产生杂交蜂群 并测量产生繁殖隔离的杂交物种的复制比例。目标2 将研究哪些生态和遗传因素促进了杂交物种的形成。目标3将评估基因变化 这些平行的实验混合物种形成事件的基础，并特别测试了之前发表的 关于杂交物种形成的遗传原因的假说。 方法：果蝇属果蝇可以在实验室条件下维持，并有一个 无与伦比的分子、遗传和基因组工具库。这一提议代表了一种实验性的演变 利用35对果蝇杂交物种来了解杂交物种形成的频率 发生。然后，我将收集全基因组数据，并识别与杂交物种形成相关的等位基因。 实验进化和作图组件的初步结果都很有希望。 与健康相关：既有通过杂交形成物种的普遍程度的问题，也有我们对 回答它们--一种检测杂交基因组中混合物质的新模型--与人类健康相关。 首先，昆虫物种之间的杂交可能会产生新的疾病媒介。然而，或有证据表明 反对杂交物种形成的情况仍然很少。第二，我们开发的计算工具是灵活的 足够在任何生物体中使用，并且它们提供了比其他现有方法更好的优势。 影响：混合物种形成是最难得出结论的物种形成过程之一， 因为通常不可能排除其他解释。实验进化提供了一种手段 毫不含糊地观察杂交物种形成。这项建议的结果可以解决关于 杂交物种形成的盛行。重要的是，结果还将揭示是否存在特定水平的 最适合杂交物种进化的遗传分化。

ABSTRACT/PROJECT SUMMARY Background: Hybrid speciation—when hybrids become reproductively isolated from their parental species—is argued to be common in plants, but the importance of the process in animals is hotly debated. The difficulty of obtaining evidence for animal hybrid speciation has led to two camps in speciation research: those who state that hybrid speciation in animals is rare, and those who consider the process to be rampant. The answer is bound to lie somewhere in between these two extremes, but no experimental tests have been attempted. Broad, long-term objective: My research goal is to use carefully designed experiments to understand the importance of different mechanisms of speciation. Arguably, hybrid speciation remains the most controversial of all evolutionary process that generates new lineages. Drosophila is a premier animal system to study experimental speciation and in this proposal I leverage its power to assess the importance of hybrid speciation. Specific aims: The goal of this project is to understand how likely it is for new animal species to arise through hybridization. Aim 1 will produce hybrid swarms between 35 species pairs with different levels of genetic divergence and measure what proportion of replicates give rise to reproductively isolated hybrid species. Aim 2 will study what ecological and genetic factors facilitate hybrid speciation. Aim 3 will assess the genetic changes underlying these parallel experimental hybrid speciation events, and specifically test previously published hypotheses about the genetic causes of hybrid speciation. Method: Fruit flies from the genus Drosophila can be maintained under laboratory conditions, and have an unmatched arsenal of molecular, genetic, and genomic tools. This proposal presents an experimental evolution approach using 35 hybridizing species pairs of Drosophila to understand how frequently hybrid speciation occurs. I will then gather genome wide data and identify the alleles associated with hybrid speciation. Preliminary results for the experimental evolution and mapping components are both promising. Health-relatedness: Both the questions—how prevalent is speciation by hybridization—and our approach to answering them—a new model to detect admixture in hybrid genomes—have relevance for human health. First, hybridization between insect species might generate new disease vectors. Yet, the evidence for or against hybrid speciation remains scant. Second, the computational tools we have developed are flexible enough to be used in any organism and they provide an advantage over other existing methods. Impact: Hybrid speciation is one of the most difficult speciation processes to conclusively demonstrate, because it is often impossible to rule out alternative explanations. Experimental evolution provides a means to observe hybrid speciation without ambiguity. The results from this proposal can resolve the conflict regarding the prevalence of hybrid speciation. Importantly, the results will also reveal whether there is a particular level of genetic divergence that is most suitable for the evolution of hybrid species.