Practice question

“α21 > α12 and K2 > K1” for which condition causes species 2 to outcompete species 1. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Species interactions are classified by their net effects on the fitness of each participant, but those effects can change with density, resource supply, life stage, and environmental stress. Competition reduces access to shared limiting factors, whereas predation and parasitism transfer resources from victim to consumer. The remaining alternatives—“α12 > α21 and K2 > K1”, “α21 > α12 and K2 < K1”, “α12 = α21 and K1 > K2”—refer to different states, processes, or scales and therefore do not express the same causal relationship. 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.