Species abundances and lifetimes: From neutral to niche-stabilized communities

•A model interpolating neutral and niche mechanisms is studied.•An analytical prediction for species abundance distribution (SAD) is obtained.•A mode in SAD emerges when intraspecific competition becomes stronger.•Species lifetime distribution is modified by niche stabilization.•Niche-stabilized communities sustain a larger diversity of longer-lived species.

We study a stochastic community model able to interpolate from a neutral regime to a niche partitioned regime upon varying a single parameter tuning the intensity of niche stabilization, namely the difference between intraspecific and interspecific competition. By means of a self-consistent approach, we obtain an analytical expression for the species abundance distribution, in excellent agreement with stochastic simulations of the model. In the neutral limit, the Fisher log-series is recovered, while upon increasing the stabilization strength the species abundance distribution develops a maximum for species at intermediate abundances, corresponding to the emergence of a carrying capacity. Numerical studies of species extinction-time distribution show that niche-stabilization strongly affects also the dynamical properties of the system by increasing the average species lifetimes, while suppressing their fluctuations. The results are discussed in view of the niche-neutral debate and of their potential relevance to field data.