Co-adapting but not static predators facilitate prey adaptation to a fluctuating environment

Abstract

Understanding how between-species interactions influence adaptation and population persistence in the face of environmental change is one of the greatest challenges for modern ecology and evolution, with important implications for conservation, and other applied fields. As predation is ubiquitous and may have strong demographic and selective impacts, it is likely to alter how prey respond to a changing environment. However, whether and how adaptation in prey depends on the way selection operates on predators remains little understood. We investigate this question by modeling the evolution of a preys trait whose optimum phenotype for fitness changes with the abiotic environment, and which also influences predation via its match with a trait of a predator species. We first show that when coevolutionary processes explicitly emerge from interactions among individuals, maladaptation in prey is not proportional to the difference between their optimum phenotype and that of predators, as assumed in most coevolutionary models. In a fluctuating environment, how well the prey track their moving optimum crucially depends on whether and how the predator evolves. Adaptive tracking of the optimum in prey is facilitated if predators track the same optimum, but hampered if predators have a fixed optimum, or cannot evolve. With eco-evolutionary dynamics, phenotypic mismatch reduces the population size of predators, thus decreasing the strength of predatory selection, but the qualitative influence of predation on prey maladaptation remains otherwise similar. Our findings highlight the importance of the evolutionary context of predators for their impacts on prey, and challenge conservation strategies for prey based on removing their predators. Significance statementSpecies in the wild face the dual challenge of adapting to their changing physical environment and coping with detrimental interactions with other species, including predators. While evolution by natural selection may jointly overcome both these challenges, the outcome of this process depends on whether the selective forces from predation and environmental change reinforce or oppose each other. Here, we show that the influence of coevolving predators on prey adaptation to a changing environment strongly depends on the selective scenario for the predators. Adaptation in prey is facilitated if predators also adapt to the changing environment, but hampered if selection favors a constant phenotype in predators. Our results challenge the relevance of predator removal as a conservation strategy to preserve prey.