SG: Spatial and environmental barriers to gene flow driving cyanobacterial biogeography in a river network.

人类依靠细菌来进行养分循环和许多其他基本功能。随着分子方法的改进，科学家们不断发现细菌多样性的增加。然而，科学家们并不了解这种遗传多样性与新物种和生态重要物种的进化之间的关系。需要更好地了解创造细菌多样性的过程，特别是考虑到它们在生态系统中的有用功能。这项研究将研究一组细菌，蓝藻，利用光来隔离碳和产生氧气。当距离或环境条件等障碍将它们隔离并减少种群间的基因交流时，可能会形成新的蓝藻物种。这种交换被称为“基因流动”。没有人知道是距离，还是环境的差异，阻碍了这些重要生物体的基因流动。这个项目将在加利福尼亚西北部的鳗鱼河中收集蓝藻藻垫，研究人员将调查不同地点这些垫的遗传相似性。蓝藻将从具有相似环境的遥远地点和具有不同环境的邻近地点取样。这些数据将用于确定在创造蓝藻多样性中最重要的是什么。当地一家媒体组织将在该项目上进行合作。他们将帮助一群高中生制作一部简短的科学纪录片。学生将拍摄实地和实验室的研究，以获得有关科学传播的知识。他们的影片和项目成果将被当地学校使用。本研究将调查基因组模式和生态过程，表明基因流动的空间和环境障碍如何区分蓝藻种群，产生新生的遗传多样性。预计这些障碍会在中性位点和适应性位点产生不同的核苷酸分化模式。因此，通过分析在不同空间尺度上收集的密切相关共存的野生细菌种群，可以更好地了解驱动微生物生物地理格局的过程。底栖蓝藻垫（Phormidium spp.）和环境变量将在河网中以巢式设计的方式进行采样，从温暖的阳光充足的下游栖息地到阴凉的支流，跨越不同的栖息地，成对距离从厘米到数百公里。利用全基因组宏基因组分析，将比较整个基因组中位点的核苷酸变异模式，并将用于了解1)广泛分布的蓝藻属亚种种群多样性的强度，2)蓝藻种群多样性的空间尺度，以及3)空间和环境障碍对驱动所观察到的生物地理格局的基因流动的贡献。

Humans rely on bacteria for nutrient recycling and many other essential functions. Scientists continue to discover increasing bacterial diversity as molecular methods improve. However, scientists do not understand how this genetic diversity relates to the evolution of new and ecologically important species. Better understanding of the processes that create bacterial diversity is needed, particularly in light of their useful functions in ecosystems. This research will study a group of bacteria, the cyanobacteria, that use light to sequester carbon and produce oxygen. New cyanobacterial species may form when barriers, such as distance or environmental conditions, isolate them and reduce the exchange of genes across populations. That exchange is called "gene flow". No one knows if it is distance, or the differences in environment, that prevent gene flow in these important organisms. This project will collect mats of cyanobacteria throughout the Eel River of Northwestern California, and the researchers will investigate the genetic similarity of those mats across different locations. Cyanobacteria will be sampled from distant locations with similar environments and adjacent locations with different environments. The data will be used to determine what is most important in creating cyanobacterial diversity. A local media organization will collaborate on the project. They will help a group of high school students to create a short science documentary film. Students will film the research done in the field and in the lab to gain knowledge about science communication. Their film and the project findings will be used by local schools. This research will investigate genomic patterns and ecological processes that suggest how spatial and environmental barriers to gene flow differentiate cyanobacterial populations, generating nascent genetic diversity. These barriers are predicted to produce different patterns of nucleotide differentiation at neutral and adaptive loci. Therefore, more understanding of the processes driving biogeographical patterns of microbes can be achieved with analyses of closely related co-existing wild bacterial populations collected over variety of spatial scales. Benthic cyanobacterial mats (Phormidium spp.) and environmental variables will be sampled in the river network in a nested design spanning pairwise distances of centimeters to hundreds of kilometers across diverse habitats, from warm sunny downstream habitats to cool shaded tributaries. Using whole genome metagenomic analyses, patterns of nucleotide variation at loci throughout the genome will be compared and will be used to understand 1) the strength of sub-species population diversity in a widespread cyanobacterial genus, 2) the spatial scales of cyanobacterial population diversity, and 3) the contributions of spatial and environmental barriers to gene flow in driving the observed biogeographical patterns.