Adaptive foraging under stoichiometric constraints can reshape competitive outcomes

Competition for resources is a central concept in ecology that is traditionally constrained by the Competitive Exclusion Principle, which states that n consumers cannot stably coexist on fewer than n resources. However, studies have shown that incorporating ecological stoichiometry (linking organisms' growth and survival to nutrient ratios of elements like carbon, nitrogen, and phosphorus) into competition models with two consumers feeding on a single resource reveals that nutrient composition, not just quantity, can determine competitive outcomes, potentially allowing stable coexistence regions. Building on these foundations, this study extends stoichiometric competition models to include adaptive foraging, where consumer feeding effort dynamically responds to resource quality. Two frameworks were analyzed: a base model with fixed feeding effort for both consumers and an adaptive model where the initially disadvantaged competitor's feeding effort evolves over time. Analytical and numerical results demonstrate that adaptive foraging can expand conditions for persistence, enable coexistence, and even reverse dominance hierarchies by allowing inferior consumers to compensate for nutrient or efficiency disadvantages. However, these benefits decline under extreme enrichment, where prey nutrient quality deteriorates beyond compensation limits. Additionally, the speed of adaptation influences competitive outcome, as the initially disadvantaged consumer must adapt fast enough to see the benefit of adaptation. Overall, the study shows that adaptive foraging under stoichiometric constraints fundamentally reshapes ecological competition, highlighting the interplay between nutrient dynamics, behavioral plasticity, and adaptation in maintaining biodiversity.