A mathematical model of exploitative and interference competitions in stage-structured populations

In population ecology, competition interactions between species are pivotal in shaping species growth and ecosystem stability. A prominent example is the phenomenon where one species preys on the offspring of another. This paper introduces and analyzes a novel stage-structured competition model to explore this ecological dynamic. Focusing on juvenile and adult life stages, we integrate two competition forms: exploitative (through shared resource limitation) and interference (where adults consume rival juveniles). While exploitative and interference competition are well-studied individually, their interplay in stage-structured populations remains underexplored. Our analysis reveals critical thresholds for resource abundance that determine whether species coexist, one dominates, or both perish. Remarkably, when one species inherently excels at resource exploitation, it dominates regardless of the interference rate on its rival's juveniles. Furthermore, increasing resource productivity can induce Hopf bifurcations, leading to cyclic population dynamics—a finding with implications for managing ecosystems under environmental change. Numerical simulations are given to illustrate and validate our theoretical findings. These results advance our understanding of how life-stage-specific interactions mediate coexistence and resilience in ecological communities.