Stochastic dynamics in populations with changing size
Weini Huang, Max Planck Inst. for Evolutionary Biology, Plön, Germany
Natural populations are composed of a finite number of individuals under complex interactions, which would lead to demographic fluctuations even in constant environments. Thus, individual interactions and demographic stochasticity are indivisible in some biological systems. We propose a stochastic approach to combine these two evolutionary ingredients. We assume competitive interactions between individuals of different types, which result in different carrying capacities of the population. From the same stochastic process, we can recover the competitive Lotka-Volterra dynamics in large populations and also capture the features, like extinctions, of small populations. We think this approach may be more relevant and natural to model populations in ecological processes, compared to those based on constant population size or deterministic dynamics.