Ecological drift, speciation, and the species abundance distribution
Species: — | Shannon H: — | t = 0
0.010
900
10
Hubbell's Unified Neutral Theory (2001): all individuals are ecologically equivalent —
births, deaths, and dispersal are random with no fitness differences. Despite this radical null model,
it predicts a log-series species abundance distribution matching many empirical data sets.
The fundamental biodiversity number θ = 2Jν (where ν = speciation rate) controls
species richness. Left: community grid. Right: log-binned species abundance distribution (SAD).