The equilibrium number of species on an island is a balance between:
“Colonization and extinction” for the equilibrium number of species on an island is a balance between. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. At equilibrium, species identities can continue to turn over even when richness is approximately stable. The model predicts a balance of rates, not an absence of colonization or extinction. The remaining alternatives—“Immigration and reproduction”, “Competition and predation”, “Mutation and genetic drift”—refer to different states, processes, or sca
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 1-4