In ecology, species S1 and S2 compete for shared resource R, with S1 showing superior efficiency in resource utilization. Predator P consumes both prey but at varying rates, introducing predator-mediated competition that can reverse competitive outcomes. The correct statement is option b: S1 will outcompete S2, unless the predator eats more of S1.​

Option Analysis

Option a: P will always eat S2, because it is an inferior competitor to S1
Predators select prey based on profitability, encounter rates, handling time, or defenses, not directly on interspecific competition ability. S2’s inferiority in resource use does not guarantee preferential predation by P, as P consumes both at different rates without specified bias toward inferior competitors. This option ignores variable predation rates and proves incorrect.​

Option b: S1 will outcompete S2, unless the predator eats more of S1
S1’s resource efficiency allows it to dominate without predation, driving S2 toward exclusion via competitive superiority. However, if P consumes disproportionately more S1 (the superior competitor), predation relieves pressure on S2, enabling coexistence or S2 dominance through predator-mediated effects. This aligns with ecological theory where predators prevent superior competitor exclusion.​

Option c: P has no impact on the outcome of competition between S1 and S2
Predators influence competition by altering prey densities, especially when consumption rates differ. P’s unequal predation on S1 and S2 creates apparent competition, shifting resource access and population dynamics, directly impacting outcomes. This option overlooks well-documented predator roles in community structure.​

Option d: P will always preferentially consume S1 because it will be more abundant
S1 abundance from efficiency might increase encounter rates, but preference depends on traits like profitability (E/h from optimal foraging), not abundance alone. Predators may target less defended or more profitable prey regardless of density, and the question specifies different rates without abundance-driven preference. This proves incorrect as it assumes fixed behavior contradicting variable rates.​

Ecological Implications

Superior competitors like S1 typically exclude inferiors under resource limitation alone. Predation introduces keystone effects, where differential consumption stabilizes communities by curbing dominants. CSIR NET questions test this interplay, emphasizing how predators mediate coexistence in shared-resource systems.​