Comparative genomic analysis of hybridization and speciation: uncovering genes and traits responsible for diversification

有大量的证据表明物种形成的过程，即一个物种进化成两个物种，但驱动这一过程的选择力量存在很多争议。杂交带，即不同但相关的物种接触并在一定程度上杂交的区域，为确定哪些性状与物种形成最相关提供了极好的机会。加拿大西部有许多不同的西部和东部鸟类的杂交区，这些鸟类在冰河时期在不同的南部地区分离时进化出了差异。在许多不同的杂交带中，我们将研究各种性状的变异，确定哪些性状在每个杂交带中表现出最大的变化；这些特征很可能与物种形成密切相关。我们还将使用最近开发的一种称为下一代DNA测序的遗传分析方法来识别与感兴趣的特征相关的基因。为了了解这些基因在基因组中的位置（例如，在哪个染色体上），我们将使用下一代测序来组装每个杂交区一个参考个体的基因组。一个重要的特征是季节性迁徙。许多西部和东部的物种在从繁殖地到越冬地的路线上差别很大。我们假设杂种具有中间的迁移方向，因此遭受较低的存活率。我们将使用跟踪装置和定向笼来确定每个杂交区鸟类的定向行为，并将确定与迁徙差异相关的遗传区域。我们的工作还将(1)使用基因组分析来重建可能通过其他物种杂交而产生的几个物种的历史，(2)测试是否存在某些关键的基因组区域，如性染色体，在鸟类的物种形成中发挥重要作用。通过对6组杂交物种进行基因组组装和基因性状关联研究，我们将为未来适应和物种形成的遗传基础研究提供更多知识。

There is abundant evidence for the process of speciation, whereby a single species evolves into two, but the selective forces that drive this process are under much debate. Hybrid zones, regions where different but related species come into contact and interbreed to some extent, provide excellent opportunities to determine which traits are most involved in speciation. Western Canada has many hybrid zones between distinct western and eastern forms of birds that evolved differences while they were separated in different southern regions during the Ice Ages. Across a number of different hybrid zones, we will study variation in a variety of traits, determining which traits show the sharpest change across each zone; these are likely the traits most involved in speciation. We will also use a recently developed method of genetic analysis called next-generation DNA sequencing to identify genes associated with traits of interest. To understand the location of these genes in the genome (e.g., on what chromosome), we will use next-generation sequencing to assemble the genome of one reference individual for each hybrid zone. One important trait is seasonal migration. Many pairs of western and eastern species differ dramatically in the routes that they take from their breeding ranges to their wintering ranges. We hypothesize that hybrids have intermediate migratory orientations and suffer lower survival as a result. We will determine orientation behavior of birds in each hybrid zone using tracking devices and orientation cages, and will determine the genetic regions associated with differences in migration. Our work will also (1) use genomic analysis to reconstruct the history of several species that may have arisen through hybridization of other species, and (2) test whether there are certain key genomic regions, such as the sex chromosomes, that play a strong role in speciation within birds. By generating assembled genomes and gene-trait association studies in six groups of hybridizing species, we will contribute much knowledge toward future studies of the genetic basis of adaptation and speciation.