Trait-space patterning is dictated by the tempo and mode of mutation

Abstract

In large, natural ecosystems, many ({gtrsim} 1) phenotypically relevant mutants can emerge over the characteristic turnover time of the population. When this is the case, there can be eco-evolutionary feedback between the dynamical processes that underlie mutation, selection and ecology. In this paper, we show that, owing to such feedback, the precise details of the mutational process can have a qualitative impact on the long-term behavior of an eco-evolutionary system, in contrast to the classical population genetic assumption that all mutations can be modeled with an effective, homogeneous rate. We demonstrate this in the context of a version of MacArthurs consumer-resource model in which consumers mutate along a resource preference trait-space. Starting from a stochastic individual-based model, we simulate the system in the case where mutations are exogenously generated at a fixed rate (e.g. via external mutagens) and in the case where mutations are coupled to replication (e.g. via DNA copying errors). We find that, surprisingly, replication-coupled mutations are capable of generating a patterned phase in the limit of fast ecological relaxation - precisely the regime where classical population genetic models are expected to operate. We derive the appropriate mean-field description of the stochastic model and use it to show that the patterned phase comes about due to a Turing-like mechanism driven by the non-reciprocal and nonlinear nature of replicative mutations. We demonstrate that these results are robust to demographic noise and model choices and we discuss systems in which this phenomenology might be relevant.