The biogeographic drivers and genomic architecture of speciation in Amazonian birds

与高纬度地区相比，热带地区拥有特别多的物种。我的研究调查了导致热带地区高度生物多样性过剩的因素。一个关键理论将高热带生物多样性与新物种形成的快速速度联系在一起，这要么是因为热带地区拥有更多促进物种多样化的地理障碍，要么是因为不同的种群进化得更快，成为不同的物种。我的研究计划的两个主要流派使用了许多物种的比较分析，以解决1)物种形成的地理环境，2)种群通过遗传进化成为新物种的速度。这些对比分析是在我们星球上生物多样性最丰富的热点亚马逊雨林和高纬度地区的低生物多样性地区进行的，比如加拿大。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，在区分不同的假设时具有无与伦比的敏感性。第一组项目将调查冰河时代降温期间的森林碎片化、宽阔的河流屏障和生态梯度对亚马逊地区新物种形成的贡献。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模型与大型遗传数据集相匹配来检验这些预测。第二组项目将测试热带和温带地区新形成的物种在遗传上分化的进化速度。在被地理屏障隔绝之后，种群开始积累遗传差异，最终导致生殖隔绝，无法相互生育成功的后代。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形成不同物种的中间阶段的群体中的数千个遗传标记，来研究对生殖隔离具有重要意义的遗传差异产生的速度。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，以及杂交种群分化的日期，来确定热带地区或温带地区生殖隔离的比率演变得更快。

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.