Abstract Submitted for the MAR16 Meeting of The American Physical Society Confirming Time-reversal Symmetry of a Directed Percola- tion Phase Transition in a Model of Neutral Evolutionary Dynamics 1 STEPHEN ORDWAY, DAWN KING, SONYA BAHAR, University of Missouri at Saint Louis — Reaction-diffusion processes, such as branching-coalescing random walks, can be used to describe the underlying dynamics of nonequilibrium phase transitions. In an agent-based, neutral model of evolutionary dynamics, we have previously shown that our system undergoes a continuous, nonequilibrium phase transition, from extinction to survival, as various system parameters were tuned. This model was shown to belong to the directed percolation (DP) universality class, by measuring the critical exponents corresponding to correlation length ξ ⊥ , correla- tion time ξ || , and particle density β . The fourth critical exponent that defines the DP universality class is β ’, which measures the survival probability of growth from a single seed organism. Since DP universality is theorized to have time-reversal symmetry, it is assumed that β = β ’. In order to confirm the existence of time- reversal symmetry in our model, we evaluate the system growth from a single asex- ually reproducing organism. Importantly, the critical exponent β ’ could be useful for comparison to experimental studies of phase transitions in biological systems, since observing growth of microbial populations is significantly easier than observ- ing death. 1 This research was supported by funding from the James S. McDonnell Foundation Stephen Ordway University of Missouri at Saint Louis Date submitted: 06 Nov 2015 Electronic form version 1.4