Predicting C4 Photosynthesis Evolution: Modular, Individually Adaptive Steps on a Mount Fuji Fitness Landscape
Predicting C4 Photosynthesis Evolution: Modular, Individually Adaptive Steps on a Mount Fuji Fitness Landscape
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DOI：
10.1016/j.cell.2013.04.058
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发表时间：
2013-06-20
期刊：
影响因子：
64.5
通讯作者：
Lercher, Martin J.
中科院分区：
文献类型：
--
作者：
Heckmann, David;Schulze, Stefanie;Lercher, Martin J.
进化生物学的一个终极目标是预测和实验验证宏观进化时间尺度上的适应性轨迹。对于复杂的生物系统，这一目标很少实现，因为模型通常缺乏与生物体适应性的明确关联。在这里，我们模拟了连接两个固碳系统的适宜环境：大多数植物使用的C-3光合作用，以及在环境二氧化碳水平和温度升高时更有效的C-4系统，它反复从C-3进化而来。尽管有广泛的符号上位性，但C-4光合作用在进化上是从任何中间状态通过单独的适应步骤而获得的。模拟表明，生化亚性状在模块中进化；模块的顺序和构成证实并扩展了基于物种比较的先前假设。植物物种指定的C-3-C-4中间体存在于预测的进化轨迹上，表明它们确实代表了短暂状态。与预期相反，我们在进化轨迹上没有发现适应的放缓，也没有发现适应度的增加。
An ultimate goal of evolutionary biology is the prediction and experimental verification of adaptive trajectories on macroevolutionary timescales. This aim has rarely been achieved for complex biological systems, as models usually lack clear correlates of organismal fitness. Here, we simulate the fitness landscape connecting two carbon fixation systems: C-3 photosynthesis, used by most plant species, and the C-4 system, which is more efficient at ambient CO2 levels and elevated temperatures and which repeatedly evolved from C-3. Despite extensive sign epistasis, C-4 photosynthesis is evolutionarily accessible through individually adaptive steps from any intermediate state. Simulations show that biochemical subtraits evolve in modules; the order and constitution of modules confirm and extend previous hypotheses based on species comparisons. Plant-species-designated C-3-C-4 intermediates lie on predicted evolutionary trajectories, indicating that they indeed represent transitory states. Contrary to expectations, we find no slowdown of adaptation and no diminishing fitness gains along evolutionary trajectories.