An experimental test of hybrid speciation

摘要/项目总结 背景：杂交物种形成--当杂交种在生殖上与其亲本物种隔离时--是 这一过程在植物中很常见，但在动物中的重要性却引起了激烈的争论。的难度 为了获得动物杂交物种形成的证据，在物种形成研究中出现了两个阵营： 动物中的杂交物种形成是罕见的，而那些认为这一过程猖獗的人。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 产生新血统的所有进化过程。果蝇是一个首要的研究动物系统 实验物种形成，在这个建议中，我利用它的力量来评估杂交物种形成的重要性。 具体目标：该项目的目标是了解新动物物种出现的可能性。 杂交方法AIM 1将在35个具有不同遗传水平的物种对之间产生杂交群体。 分歧，并衡量什么比例的复制品产生生殖隔离的杂交种。目的2 将研究什么生态和遗传因素促进杂交物种形成。目标3将评估基因变化 这些平行实验混合物种形成事件的基础，并专门测试先前发表的 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饲养，并具有一定的繁殖能力。 无与伦比的分子、遗传和基因组工具库。这一提议提出了一种实验性的演变 一种使用35对果蝇杂交物种来了解杂交物种形成的频率的方法， 发生。然后，我将收集全基因组数据，并确定与杂交物种形成相关的等位基因。 实验进化和映射组件的初步结果都是有希望的。 健康相关性：这两个问题-杂交物种形成的普遍程度-以及我们对 回答他们-一个新的模式来检测混合基因组中的混合物-有关系到人类健康。 首先，昆虫物种之间的杂交可能产生新的疾病载体。然而，证据或 对杂交物种形成的研究仍然很少。其次，我们开发的计算工具是灵活的 足以在任何生物体中使用，并且它们提供了优于其他现有方法的优势。 影响：混合物种形成是最难最终证明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方法， 毫不含糊地观察杂交物种形成。这一建议的结果可以解决关于 杂交物种形成的普遍性。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.