A time-averaged neutral model with environmental stochasticity
نویسندگان
چکیده
Competition is the main driver of population dynamics, which shapes the genetic composition of populations and the assembly of ecological communities. Neutral models neglect the effects of selection and niche partitioning, such that all individuals are equivalent and the dynamics is governed by demographic (shot) noise. Despite their great success in explaining static properties of communities, like species abundance distributions (SADs), the existing neutral models were criticized for making unrealistic predictions of fundamental dynamic patterns. A time-averaged neutral model, in which environmental variations affect coherently the relative fitness of entire populations, has been suggested to account for this problem. Here we solve for the SAD of a well-mixed, time-averaged neutral model in a community of size N . A self-consistent mean-field approach is used to reduce the multi-species problem to two-species dynamics, and the large-N asymptotics of the emerging set of Fokker-Planck equations is obtained. Our analytic expressions are shown to fit the SADs obtained from extensive Monte-Carlo simulations and from numerical solutions of the corresponding master equations.
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