Speciation forms new species.
Directional selection favors one extreme of a phenotype, which leads to evolution and adaptive change of a species.
Disruptive selection selects against the average and leads to evolution and genetic variation of a species.
Stabilizing selection favors the average individual in a population, which does not lead to adaptive change or evolution, and reduces variation.
I’m pretty sure the answer is half life decay, we did an experiment in my science class on it last year.
A community with lots of plants and animals, that have a equal balance between them that is success of a community which can only be destroyed by a fire or human causes.