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

GUADALUPE CASCALLARES; PABLO M GLEISER

Papers in Physics

Papers in Physics

Año: 2015 vol. 7

1852-4249

Nearly all living organisms, including some bacterial species, exhibit biological processeswith a period of about 24 h called circadian (from the Latin circa, about and dies, day)rhythms. These rhythms allow living organisms to anticipate the daily alternation oflight and darkness. Experiments carried out in cyanobacteria have shown the adaptivevalue of circadian clocks. In these experiments, a wild type cyanobacterial strain (witha 24 h circadian rhythm) and a mutant strain (with a longer or shorter period) grow incompetition. In different experiments, the external light dark cycle was chosen to matchthe circadian period of the different strains, revealing that the strain whose circadian periodmatches the light-dark cycle has a larger fitness. As a consequence, the initial populationof one strain grows while the other decays. These experiments were made under fixedlight and dark intervals. In Nature, however, this relationship changes according to theseason. 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 survivalof the different cyanobacterial strains. Our results show that there is a clear shift in thecompetition due to the modulation of light, which could be verified experimentally.