Stochastic community assembly with speciation, drift, and immigration
Hubbell's Unified Neutral Theory (2001) proposes that all species are functionally equivalent — community dynamics arise purely from demographic stochasticity, speciation, and dispersal. Each time step: a random individual dies and is replaced by offspring from (1) a local individual (with prob 1-m) or (2) a metacommunity immigrant (prob m). New species arise at rate ν. The theory predicts a log-series species abundance distribution, matching tropical forest data.