Consumer power as the major evolutionary force.

Each trophic level in evolving ecosystems can behave as either a supplier toward the downstream of trophic energy flow or a consumer toward the upstream, or an arbitrary mixture of the two. We show that each trophic level behaves almost completely as a consumer in evolutionarily sustainable ecosystems. The present prevalence of consumers in evolving ecosystems derives from a model trophic dynamics minimizing the artificial constraints to be applied arbitrarily.