Evolution of a Fluctuating Population in a Switching Environment: Random versus Periodic

Environmental changes greatly influence the evolution of populations. In this talk, we discuss the dynamics of a population of two strains, one growing slightly faster than the other, competing for resources in a time-varying binary environment modeled by a carrying capacity that switches either randomly or periodically between states of resources abundance and scarcity [1,2]. The population dynamics is characterized by demographic noise (birth and death events) coupled to the fluctuating population size [2,3]. By combining analytical and simulation methods, we elucidate the similarities and differences of evolving subject to stochastic and periodic switching. The population size distribution is generally found to be broader under intermediate and fast random switching than under periodic variations. This results in markedly different asymptotic behaviors of the fixation probability under random and periodic switching environments [1]. We also determine the conditions under which the fixation probability of the slow strain is maximal [1].[1] A. Taitelbaum, R. West, M. Assaf, and M. Mobilia, Physical Review Letters 125, 048105:1-6 (2020).[2] K. Wienand, E. Frey, and M. Mobilia, Physical Review Letters 119, 158301:1-6 (2017) and J. Royal Society Interface 15, 20180343:1-12 (2018).[3] R. West and M. Mobilia, Journal of Theoretical Biology 491, 110135:1-14 (2020).