the Hubbell point, an egalitarian coexistence stable fixed point where all species are present on the island with the same abundance $K/(1+(Q-1)C)$, while above the Hubbell point the stable solution admits only one species with abundance $K$, all other species has zero abundance (the identity of the surviving species is determined by initial conditions). At the Hubbell point the deterministic dynamics supports a marginal manifold: every combination of $N_i$’s such that the total population is $K$ is a solution of Eq. \[GLV1\]. The simplicity of the GCLV at the Hubbell point allows one to solve analytically for the species abundance distributions (SAD) even with demographic noise [@maritan1], environmental stochasticity [@malcai2002theoretical], or a combination of demographic and environmental noise [@kessler2014neutral].

About 15 years ago, Hubbell [@Hubbell2001unifiedNeutral] put forward his very influential neutral theory of biodiversity, suggesting that all species and all individuals are demographically equivalent and the only mechanism that drives the system is pure demographic noise and the (typically slow) rate in which new species are introduced. Hubbell’s model has two versions. In the metacommunity version speciation is the mechanism that leads to the introduction of a new species, while in the mainland-island version colonizers of new species arrive from 