Fitness-driven adaptive competition as a double-edged mechanism in maintaining biodiversity under cyclic competition

Understanding how adaptive mechanisms influence species coexistence remains a central issue in evolutionary ecology. In this study, we propose a spatial rock-paper-scissors model that incorporates fitness-driven adaptive competition, where the intensity of interspecific interactions dynamically adjusts according to local environmental fitness. Using extensive Monte Carlo simulations, we systematically explore how the sensitivity parameter (K) and migration rate (M) jointly shape spatial patterns, extinction probabilities, and long-term biodiversity. The results demonstrate that moderate fitness heterogeneity and intermediate dispersal rates favor the persistence of coexistence by stabilizing oscillatory dynamics and maintaining spiral-wave structures. In contrast, excessive sensitivity or mobility leads to spatial homogenization and increased extinction risks. These findings highlight the dual role of adaptability as both a stabilizing and destabilizing force in cyclic competition, offering new theoretical insights into the ecological mechanisms underlying biodiversity maintenance and informing conservation strategies that balance migration and environmental adaptation.