The eco-evolution and diversification in antagonistic and mutualistic interactive populations

Understanding environmental and ecological effects on ecosystem structure, function, and dynamics is crucial. However, our comprehension of such effects remains challenging due to the complex interplay of abiotic environment, ecological relationships among species, and coevolution within and across trophic levels. Here, we set out to investigate a wide range of combined ecoevolutionary responses in a plant-insect ecosystem. We study ecological population dynamics, coevolution and functional diversity in response to changes in (1) abiotic-biotic interactions, (2) within-trophic-level competitive interactions, and (3) between-trophic-level antagonistic and mutualistic interactions. We developed an eco-evolutionary and functional trait-based model to simulate environmental and ecologically mediated responses to these interactions. We show that mutualistic interactions render a positive feedback loop of increased population sizes followed by selection for even stronger biotic ecological interactions instead of abiotic interactions. Antagonistic interactions have the opposite effect and adaptation to abiotic environment becomes more important. Furthermore, our study reveals that benign conditions (high ecological opportunities, low within-trophic-level competition, and strong interactions between plants and insects) facilitate functional diversity, whereas harsh conditions impede diversity. These findings provide valuable insights into mechanisms that underlie fundamental eco-evolutionary responses to current environmental and ecological changes, offering potential contributions to ecosystem conservation facing urgent challenges.