The population genomics of hybridization: from adaptation to genome evolution

项目总结 现在很明显，物种之间的杂交比以前认识到的要普遍得多。 因此，我们现在意识到，包括我们自己在内的许多现代物种的基因组是一种 从过去的杂交事件中衍生出来的区域拼接。尽管越来越多的人对 尽管杂交普遍存在，但我们对杂交对适应和适应的影响了解很少 基因组进化。解决这些主题是实验室研究的主要重点。一个悬而未决的问题是 杂交祖先在基因组中的什么位置存在，以及是什么过程塑造了这种分布。最近的工作， 包括我自己的，已经证明了基因组中具有更高基因密度和保守性的区域 元素不太可能在物种之间移动。虽然这一总体模式已经确立， 杂交后选择的单个基因座的鉴定及其选择机制 对这些区域采取行动仍然是一个重大挑战。拟议的工作将利用密集的时间序列抽样 对剑尾鱼杂交种群的研究，一个研究杂交的模式系统，以开发新的方法 来解决这些问题。 尽管在大多数情况下，对不同物种之间的杂交有很强的选择， 有时，杂交可以允许适应性等位基因在物种之间移动。已知的此类示例 “适应性渗透”包括在疟疾中传播对啮齿动物毒药和杀虫剂的抗药性。 蚊子。目前用于检测此类事件的方法的一个缺点是它们忽略了流行率 负选择而不是杂交，这可能会掩盖信号。我们建议开发新的方法 用于鉴定在这方面表现良好的杂交后的选择和适应性导入。 这项工作将对杂交在适应和特征进化中的作用产生新的见解。 此外，杂交可以对基因组进化产生全球影响。因为杂交结合了 两个不同的基因组，这也可能意味着组合两个不同的重组景观(因为在一些 案例重组热点在物种间进化迅速)。事实上，重组分歧一直是 与某些物种的杂交不育有关。我们将使用建模来探索如何重组景观 在具有不同指定重组机制的物种中杂交后预计会进化 热点，并将其与我们将生成的经验数据进行比较。共同努力，这项工作将给予前所未有的 深入了解杂交如何影响基因组的进化，从对单个基因座的选择到 基因组的结构。 好了！

Project summary It is now clear that hybridization between species is much more common than previously recognized. As a result, we are now realizing that the genomes of many modern species, including our own, are a patchwork of regions derived from past hybridization events. Despite this increasing appreciation of the ubiquity of hybridization, we still understand very little about the impact of hybridization on adaptation and genome evolution. Addressing these topics is the major focus of research in the lab. An outstanding question is where in the genome hybrid ancestry persists and what processes shape this distribution. Recent work, including my own, has demonstrated that regions of the genome with higher densities of genes and conserved elements are less likely to move between species. While this general pattern has been well-established, identifying the individual loci under selection after hybridization and the mechanisms of selection acting on these loci remains a major challenge. The proposed work will leverage dense time-series sampling of hybrid populations of swordtail fish, a model system for studying hybridization, to develop new approaches to address these questions. Although in most cases there is strong selection against hybridization between divergent species, sometimes hybridization can allow adaptive alleles to move between species. Known examples of such “adaptive introgression” include the spread of resistance to rodent poisons and to insecticides in malarial mosquitoes. One shortcoming of current methods for detecting such events is that they ignore the prevalence of negative selection against hybridization, which can obscure signals. We propose to develop new methods for identifying selection and adaptive introgression after hybridization that perform well in this context. This work will yield new insights into the role of hybridization in adaptation and trait evolution. In addition, hybridization can have global impacts on genome evolution. Since hybridization combines two divergent genomes, this can also mean combining two different recombination landscapes (since in some cases recombination hotspots evolve quickly between species). Indeed, recombination divergence has been implicated in hybrid sterility in some species. We will use modeling to explore how recombination landscapes are expected to evolve after hybridization in species with different mechanisms for specifying recombination hotspots, and compare this to empirical data we will generate. Together, this work will give unprecedented insight into how hybridization impacts the evolution of the genome, from selection on individual loci to the structure of the genome. !