Microevolution and population dynamics of Prochlorococcus cells in the ocean: Insights through single-cell genomics

原绿球藻是一种在世界海洋中广泛存在的细菌。 作为一种光合作用细胞，它利用阳光将二氧化碳固定为有机碳，类似于陆地上的植物。海洋中的全球原绿球藻种群由多种“生态类型”组成，每种类型的最佳生长条件略有不同。据推测，这组微生物的多样性使其能够在广泛变化的海洋栖息地中茁壮成长，但对这种多样性的遗传基础知之甚少。这项研究旨在通过研究一年中不同时间从大西洋和太平洋分离的单个野生原绿球藻细胞的遗传组成，促进我们对原绿球藻生态和进化的理解。 这项研究的动机是两个基本问题：（i）细胞的遗传组成与其生态动力学之间的关系是什么？(ii)在生态和进化的时间尺度上，种群如何适应环境？这项工作的更广泛意义在于原绿球藻在海洋生态和全球碳循环中发挥的核心作用。 原绿球藻是海洋中最丰富的光合类群，是食物网基础的重要组成部分。 由于它进行了相当大一部分的海洋光合作用，它在全球碳循环和全球气候过程中发挥着重要作用。 了解是什么调节原绿球藻的多样性和动态对于开发这些重要地球系统特征的预测模型至关重要。

Prochlorococcus is a bacterium that is widespread and abundant in the world oceans. As a photosynthetic cell, it uses sunlight to fix carbon dioxide into organic carbon, similar to plants on land. The global Prochlorococcus population in the oceans is made up of a diversity of "ecotypes," each of which has slightly different conditions for optimal growth. It is hypothesized that the diversity of this group of microbes allows it to thrive over broadly varying ocean habitats, but the genetic underpinnings of this diversity is very poorly understood. This research aims at advancing our understanding of the ecology and evolution of Prochlorococcus, by studying the genetic composition of single wild Prochlorococcus cells isolated from the Atlantic and Pacific oceans at different times of year. The study is motivated by two fundamental questions: (i) what is the relationship between the genetic composition of the cells and their ecological dynamics? (ii) how do populations adapt to their environment over ecological and evolutionary time scales?The broader significance of this work lies in the central role that Prochlorococcus plays in ocean ecology and the global carbon cycle. As the most abundant photosynthetic group in the oceans, Prochlorococcus is a critical component of the base of the food web. Because it conducts a sizable fraction of ocean photosynthesis, it plays an important role in the global carbon cycle and global climate processes. Understanding what regulates Prochlorococcus' diversity and dynamics is critical for developing predictive models of these important Earth system features.