A Model Simulation of the Adaptive Evolution through Mutation of the Coccolithophore Emiliania huxleyi Based on a Published Laboratory Study
A Model Simulation of the Adaptive Evolution through Mutation of the Coccolithophore Emiliania huxleyi Based on a Published Laboratory Study
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基于已发表的实验室研究的球石藻突变适应性进化的模型模拟
DOI：
10.3389/fmars.2016.00286
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发表时间：
2017
影响因子：
3.7
通讯作者：
K. Denman
中科院分区：
文献类型：
--
作者：
K. Denman
我们预计海洋生态系统的结构和功能将在本世纪发生变化，以响应与气候变化有关的关键海洋变量的变化。世代周期从几年到几十年的生物体有能力在几代内通过从现有的基因型/表型中进行选择来适应不断变化的环境条件，但通过突变的进化不太可能成为世代周期为几年到几十年的生物体的主要因素。然而，浮游植物和其他微生物的繁殖周期为几天或更短，每年经历数百代，这使得有利突变（即产生最适合当时环境条件的生物体）有可能主导现有的基因型，并在不断变化的气候中生存下来。几个实验室已经培养了数百到数千代的浮游植物，并证明它们已经改变了基因组成。特别是Schluter等人（2014）在15°C条件下培养了3年（~1250代）来自赫胥利Emiliania huxleyi单细胞的重复，这是一种具有广泛地理和热范围的球石藻，然后在接近其最高热极限的26.3°C条件下培养了一年。在过去一年中，内在增长率或多或少呈线性增长，作者将其归因于基因突变。在这里，我们模拟了单个性状（内在增长率）的基因突变，包括控制阶段和温暖阶段的研究。我们考虑对突变频率的敏感性，内在生长速率随温度的变化，并使用实验设置和结果来限制突变发生的方式。特别是，所有带突变的数值实验都需要30-140代的滞后时间，才能使实际生长率显著提高。有利突变后的滞后是由于单个有利突变细胞需要数代才能达到培养中约105个细胞的很大一部分。一个包含简单塑性响应公式的数值实验表明，塑性可以消除这种滞后，并且产生的结果与实验室研究中观察到的结果更一致。
We expect the structure and functioning of marine ecosystems to change over this century in response to changes in key ocean variables associated with a changing climate. Organisms with generation times from years to decades have the capacity to adapt to changing environmental conditions over a few generations by selecting from existing genotypes/phenotypes, but it is unlikely that evolution through mutation will be a major factor for organisms with generation times of years to decades. However, phytoplankton and other microbes, with generation times of days or less, experience hundreds of generations each year, allowing the possibility for favorable mutations (i.e., those that produce organisms with fitness maxima nearer to the environmental conditions at that time) to dominate existing genotypes and survive in a changing climate. Several laboratories have grown phytoplankton cultures for hundreds to thousands of generations and demonstrated that they have changed genetic makeup. In particular Schluter et al (2014) grew replicates derived from a single cell of Emiliania huxleyi, a coccolithophorid with broad geographical and thermal range, for 3 years (~1250 generations) at 15°C, and then for a year at 26.3°C, near their upper thermal limit. During the last year the intrinsic growth rate increased more or less linearly, which the authors attribute to genetic mutation. Here we simulate genetic mutation of a single trait (intrinsic growth rate), both for the control phase and the warm phase of their study. We consider sensitivities to frequency of mutation, changes with temperature in intrinsic growth rate, and use the experimental setup and results to place constraints on the way mutations occur. In particular, all numerical experiments with mutation result in a lag time ~30-140 generations before a significant increase in realized growth rate occurs. This lag after a favorable mutation results from the number of generations required for a single favorable mutant cell to reach a significant fraction of the ~105 cells in the culture. A numerical experiment that includes a simple plastic response formulation shows that plasticity could remove this lag and yield results more in agreement with those observed in the laboratory study.
影响因子：
30.7
作者：
Lothar Schlüter;Kai T. Lohbeck;M. Gutowska;J. Gröger;U. Riebesell;T. Reusch
通讯作者：
Lothar Schlüter;Kai T. Lohbeck;M. Gutowska;J. Gröger;U. Riebesell;T. Reusch
影响因子：
18.3
作者：
Lohbeck, Kai T.;Riebesell, Ulf;Reusch, Thorsten B. H.
通讯作者：
Reusch, Thorsten B. H.
影响因子：
4.9
作者：
Daniels, C. J.;Sheward, R. M.;Poulton, A. J.
通讯作者：
Poulton, A. J.