Which outcome is possible in unstable coexistence?
“One species wins depending on initial densities” for which outcome is possible in unstable coexistence. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Coexistence requires stabilizing differences that make each species limit itself more strongly than it limits its competitor, or an equalizing process that keeps fitness differences small. Without such mechanisms, persistent competitive asymmetry tends toward exclusion. The remaining alternatives—“Both species persist regardless of initial conditions”, “Neither species wins”, “One species always dominates”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Evidence should connect encounter rates or resource use to survival, growth, or reproduction. The ecological label follows that causal effect rather than superficial proximity between organisms. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 13-14