DISSERTATION RESEARCH: Molecular basis of hummingbird distributions in the high Andes

该项目将调查南美洲海拔梯度上蜂鸟物种的分布与极端条件遗传适应的分子基础之间的联系。我们知道环境变化会影响物种的进化和分布。然而，我们不知道生物体如何适应这种变异的分子基础。一个主要的挑战是了解在当地种群中发生的分子过程如何与全球物种在进化过程中的分布模式相关。这很困难，因为适应的证据可能会随着时间的推移而消失，而且种群遗传模式可以模仿适应。这个项目将比较安第斯蜂鸟的几个种群和物种。现代遗传学方法将被用来衡量蛋白质的自然选择，同时也考虑到种群的遗传结构。此外，该项目将包括对高中生和本科生的培训，并为基因组工作室制作教材。该项目将弥合宏观进化分布模式和适应的微观进化过程之间的差距。目标是测试安第斯蜂鸟种群对高海拔条件的遗传适应性，同时控制人口历史，并测试独立殖民安第斯山脉高地的种群之间的平行进化。蜂鸟是研究跨海拔梯度遗传适应的一个很好的系统。有300多个物种，它们分布在一个巨大的梯度上--海平面到4000米以上--尽管它们的基本代谢率是所有鸟类中最高的，而且至少有四次高海拔栖息地的独立殖民事件。研究人员将收集两个低海拔物种和两个高海拔物种的6-30个种群的基因组数据，以验证这样一个假设，即蛋白质编码基因的适应性变化决定了最近定居在安第斯高地的蜂鸟种群的海拔分布。研究人员将使用基因组数据来检测正选择的特征，这是遗传适应的指标，并测量不同种群的种群遗传结构。这些分析的结果将对殖民和适应高海拔生态系统的机制提供重要的洞察。

This project will investigate the link between the distribution of hummingbird species across an elevational gradient in South America and the molecular basis of genetic adaptation to extreme conditions. We know that environmental variation effects the evolution and distribution of species. However, we do not know the molecular bases for how organisms adapt to this variation. A major challenge is to understand how molecular processes occurring in local populations relate to global species' distribution patterns over evolutionary time. This is difficult because evidence of adaptation can disappear over time, and because population genetic patterns can mimic adaptation. This project will compare several populations and species of Andean hummingbirds. Modern genetic methods will be used to measure natural selection on proteins while also taking account of population genetic structure. In addition, the project will include the training of high school and undergraduate students, and produce educational materials for genomic workshops.This project will bridge the gap between macroevolutionary distribution patterns and microevolutionary processes of adaptation. The goals are to test for genetic adaptation to high-altitude conditions in Andean hummingbird populations while controlling for demographic history, and to test for parallel evolution across populations that independently colonized the high Andes. Hummingbirds are an excellent system for studying genetic adaptation across altitudinal gradients. There are more than 300 species, they occur across a vast gradient - sea level to over 4000 meters - despite having the highest basal metabolic rates of any bird group, and there have been at least four independent colonization events of high-altitude habitats. The researchers will collect genomic data from 6-30 populations of two low and two high altitude species to test the hypothesis that adaptive changes in protein-coding genes shape altitudinal distributions in hummingbird populations that have recently colonized the high Andes. Researchers will use the genomic data to detect signatures of positive selection, an indicator of genetic adaptation, and measure population genetic structure across populations. The results of these analyses will provide critical insight into the mechanisms of colonization and adaptation to high elevation ecosystems.