Metabolic evolution and the self-organization of ecosystems
Metabolic evolution and the self-organization of ecosystems
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DOI：
10.1073/pnas.1619573114
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发表时间：
2017-04-11
影响因子：
11.1
通讯作者：
Chisholm, Sallie W.
中科院分区：
文献类型：
--
作者：
Braakman, Rogier;Follows, Michael J.;Chisholm, Sallie W.
新陈代谢调节着生物圈中物质和能量的流动。我们研究了代谢进化如何通过在全球丰富的海洋植物浮游植物原绿球藻中重建生态系统来塑造生态系统。为了理解是什么驱动了观察到的进化模式，我们在其种群动态，生长速率和光适应，以及细胞的大小，大分子和元素组成的背景下对其进行了解释。这种多层次的观点表明，在进化过程中，原绿球藻的代谢率和有机碳的排泄量稳步增加。我们推导出一个数学框架，表明这些适应降低了细胞的最低生存营养浓度，从而导致海洋表面沃茨中营养物质的下降。这反过来又增加了生态系统的总生物量，促进了生态系统中所有细胞的共同进化。额外的重建表明，原绿球藻和占主导地位的共生异养细菌SAR11形成了共同进化的互惠共生，通过互补的排泄和吸收途径回收有机碳，最大限度地提高其集体代谢率。此外，原绿球藻和SAR11的代谢相互依赖性与植物细胞内叶绿体和线粒体的代谢相互依赖性高度相似。这些观察使我们提出了一个一般理论，将新陈代谢进化与生物圈的自我放大和自我组织联系起来。我们讨论了这个框架的地球的地球化学循环的演变和大气中氧气的上升的影响。
Metabolism mediates the flow of matter and energy through the biosphere. We examined how metabolic evolution shapes ecosystems by reconstructing it in the globally abundant oceanic phytoplankter Prochlorococcus. To understand what drove observed evolutionary patterns, we interpreted them in the context of its population dynamics, growth rate, and light adaptation, and the size and macromolecular and elemental composition of cells. This multilevel view suggests that, over the course of evolution, there was a steady increase in Prochlorococcus' metabolic rate and excretion of organic carbon. We derived a mathematical framework that suggests these adaptations lower the minimal subsistence nutrient concentration of cells, which results in a drawdown of nutrients in oceanic surface waters. This, in turn, increases total ecosystem biomass and promotes the coevolution of all cells in the ecosystem. Additional reconstructions suggest that Prochlorococcus and the dominant cooccurring heterotrophic bacterium SAR11 form a coevolved mutualism that maximizes their collective metabolic rate by recycling organic carbon through complementary excretion and uptake pathways. Moreover, the metabolic codependencies of Prochlorococcus and SAR11 are highly similar to those of chloroplasts and mitochondria within plant cells. These observations lead us to propose a general theory relating metabolic evolution to the self-amplification and self-organization of the biosphere. We discuss the implications of this framework for the evolution of Earth's biogeochemical cycles and the rise of atmospheric oxygen.