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

该项目将调查蜂鸟物种在南美洲海拔梯度上的分布与极端条件下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，我们不知道生物如何适应这种变化的分子基础。一个主要的挑战是了解在进化过程中发生在当地种群中的分子过程与全球物种分布模式之间的关系。这很困难，因为适应的证据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。这个项目将比较几个种群和种类的安第斯蜂鸟。现代遗传方法将用于测量蛋白质的自然选择，同时也考虑到群体遗传结构。此外，该项目将包括对高中生和大学生的培训，并为基因组研讨会制作教育材料。这个项目将弥合宏观进化分布模式和微观进化适应过程之间的差距。目标是在控制人口历史的情况下，测试安第斯山脉蜂鸟种群对高海拔条件的遗传适应性，并测试独立定居安第斯山脉的种群之间的平行进化。蜂鸟是研究跨越海拔梯度的遗传适应的一个极好的系统。有超过300种，它们分布在一个巨大的梯度-海平面超过4000米-尽管具有最高的基础代谢率的任何鸟类群体，并有至少四次独立的殖民化事件的高海拔栖息地。研究人员将收集6-30个低海拔和高海拔物种的基因组数据，以验证蛋白质编码基因的适应性变化塑造了最近定居安第斯山脉高海拔地区的蜂鸟种群的海拔分布的假设。研究人员将使用基因组数据来检测积极选择的特征，这是遗传适应的一个指标，并测量种群间的种群遗传结构。这些分析的结果将为高海拔生态系统的殖民化和适应机制提供关键的见解。

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.