标题： 你最适合哪个季节？ 季节性光照变化和蓝藻竞争 显示英文标题

标题： What season suits you best? Seasonal light changes and cyanobacterial competition

摘要： 几乎所有的生物体，包括一些细菌种类，都表现出大约24小时周期的生物过程，称为昼夜节律（来自拉丁语circa，意为大约，dies，意为天）。这些节律使生物体能够预期日常的光照和黑暗交替。在蓝藻中进行的实验表明了昼夜节律的适应价值。在这些实验中，野生型蓝藻菌株（具有24小时的昼夜节律）和突变菌株（具有更长或更短的周期）在竞争中生长。在不同的实验中，外部光照周期被改变以匹配不同菌株的昼夜节律，结果表明，其昼夜节律与光照周期相匹配的菌株具有更大的适应性。因此，一种菌株的初始种群增长而另一种则衰退。这些实验是在固定的光照和黑暗间隔下进行的。然而，在自然环境中，这种关系会随着季节变化。因此，光照的季节性变化可能会影响竞争的结果。通过一个理论模型，我们分析了光照调制如何改变不同蓝藻菌株的生存。我们的结果表明，由于光照的调制，竞争出现了明显的转变，这可以在实验中得到验证。 显示英文摘要

摘要： Nearly all living organisms, including some bacterial species, exhibit biological processes with a period of about 24 h called circadian (from the Latin circa, about, dies, day) rhythms. These rhythms allow living organisms to anticipate the daily alternation of light and darkness. Experiments carried out in cyanobacteria have shown the adaptive value of circadian clocks. In these experiments a wild type cyanobacterial strain (with a 24 h circadian rhythm) and a mutant strain (with a longer or shorter period) grow in competition. In different experiments the external light dark cycle was changed in order to match the circadian period of the different strains, revealing that the strain whose circadian period matches the light-dark has a larger fitness. As a consequence the initial population of one strain grows while the other decays. These experiments were made under fixed light and dark intervals. However, in Nature this relationship changes according to the season. Therefore, seasonal changes in light could affect the results of the competition. Using a theoretical model we analyze how modulation of light can change the survival of the different cyanobacterial strains. Our results show that there is a clear shift in the competition due to the modulation of light, which could be verified experimentally.