Response delay as a strategy for survival in fluctuating environment

Response time-delay is an ubiquitous phenomenon in biological systems. Here we use a simple stochastic population model with time-delayed switching-rate conversion to quantitatively study the biological influence of the response time-delay on the survival fitness of cells living in periodically fluctuating and stochastic environment, respectively. Our calculation and simulation show that for the cells having a slow rate transition into fit phenotype and a fast rate transition into unfit phenotype, the response time-delay can always enhance their fitness during the environment change. Particularly, in the periodic or stochastic environment with small variance, the optimal fitness achieved by these cells is superior to that of cells with reverse switching rates even if the latter exhibits rapid response. These results suggest that the response time delay may be utilized by cells to enhance their adaptation to the fluctuating environment.