Apparent decoupling of eco-evolutionary dynamics in a dual-trait predator–prey interaction

Predator-prey coevolution is often characterized by ongoing arms races-so-called Red Queen dynamics-where reciprocal selection drives persistent trait oscillations. These evolutionary cycles can destabilize population dynamics and hinder coexistence. While classic models typically focus on evolution along a single ecological axis, real-world interactions often involve multiple, functionally distinct trait dimensions. Here, I extend a classic framework by allowing both predator and prey to evolve along two distinct trait dimensions-such as spatial and temporal niches. I find that, in contrast to one-dimensional predictions, rapid prey evolution in a multidimensional trait space can stabilize population dynamics and yield a stable ecological equilibrium, even as traits continue to undergo persistent coevolutionary cycles. This apparent decoupling of ecological and evolutionary dynamics arises when prey evolution is constrained-specifically, when simultaneous adaptation across trait axes is limited. Under such constraints, lags arise in the dynamics between traits, and the effects of trait changes on population dynamics are weakened because these effects are offset either among traits within species or across species. As a result, while traits may continue to oscillate in a coevolutionary "arms race," population sizes remain stable. The findings demonstrate that multidimensional trait evolution fundamentally alters eco-evolutionary outcomes, suggesting that apparent ecological stability may conceal active evolutionary races.