The biogeographic drivers and genomic architecture of speciation in Amazonian birds

与高纬度地区相比，热带地区拥有数量惊人的物种。我的研究调查了导致热带地区高生物多样性过度的因素。一个关键的理论将高热带生物多样性与新物种形成的快速速度联系起来，这要么是因为热带地区拥有更多的地理障碍，促进了物种的多样化，要么是因为不同的种群更快地进化成不同的物种。我的研究计划的两个主要流使用许多物种的比较分析来解决1）物种形成的地理环境，和2）种群遗传进化成为新物种的速率。这些比较分析是在我们星球上最具生物多样性的热点地区亚马逊雨林与高纬度地区的低生物多样性地区（如加拿大）进行的。对于这两个流，我将使用尖端的下一代测序数据集，包括数千个遗传标记，在区分替代假设时具有无与伦比的灵敏度。第一组项目将调查冰河时期冷却、宽河流屏障和生态梯度期间森林破碎化对亚马逊新物种形成的贡献。这些地理情景中的每一个都做出了不同的预测，可以通过将人口历史的人口统计模型拟合到大型遗传数据集来进行测试。第二组项目将测试新形成的物种在热带和温带地区的进化速度。在地理隔离之后，种群开始积累遗传差异，最终导致生殖隔离，即彼此不能产生成功的后代。生殖隔离标志着新物种形成过程的完成，一旦出现，对维持多样性至关重要。我的实验室将通过分析仍在杂交并处于成为不同物种的中间阶段的成对种群中的数千个遗传标记来研究对生殖隔离重要的遗传差异出现的速度。我们将量化未能跨越种群边界的遗传标记的比例（这些标记表明可能存在导致生殖隔离的基因），并使用这些标记，沿着杂交种群分化的日期，以确定热带或温带地区的生殖隔离率是否进化得更快。

The tropics possess exceptional numbers of species when compared to high latitudes. My research investigates the factors that drive the excess of high biodiversity in tropical regions. A key theory links high tropical biodiversity to a fast rate at which new species form, either because the tropics possess more geographic barriers that promote species diversification, or because diverging populations evolve more rapidly to become distinct species. The two major streams of my research program use comparative analyses across many species to address 1) the geographic setting of species formation, and 2) the rates at which populations evolved genetically to become new species. These comparative analyses are performed in the most biodiverse hotspot on our planet the Amazon rainforest versus low biodiversity areas at high latitude regions, like Canada. For both streams, I will use cutting-edge next generation sequencing datasets comprising thousands of genetic markers that allow for unparalleled sensitivity in discriminating between alternative hypotheses. The first set of projects will investigate the contribution of forest fragmentation during periods of ice age cooling, wide river barriers, and ecological gradients to the formation of new species in the Amazon. Each of these geographic scenarios make distinct predictions that can be tested by fitting demographic models of population history to large genetic datasets. The second set of projects will test the evolutionary speed at which newly formed species diverge genetically in tropical versus temperate regions. Following isolation by geographic barriers, populations begin to accumulate genetic differences, which eventually result in reproductive isolation the inability to produce successful offspring with each other. Reproductive isolation marks the completion of the process by which new species form and is vital to the maintenance of diversity once it arises. My lab will study the pace at which genetic differences important to reproductive isolation arise by analyzing thousands of genetic markers in pairs of populations which still hybridize and are in the intermediate stages of becoming distinct species. We will quantify the proportion of genetic markers that fail to cross population boundaries (such markers indicate the likely presence of a gene causing reproductive isolation) and use these, along with dates at which hybridizing populations diverged, to determine if rates of reproductive isolation evolve faster in tropical or temperate regions.