A stabilizing eco-evolutionary feedback loop in the wild

There is increasing evidence that evolutionary and ecological processes can operate on the same timescale (i.e., contemporary time). As such, evolution can be sufficiently rapid to affect ecological processes such as predation or competition. Thus, evolution can influence population, community, and ecosystem-level dynamics. Indeed, studies have now shown that evolutionary dynamics can alter community structure and ecosystem function. In turn, shifts in ecological dynamics driven by evolution might feed back to affect the evolutionary trajectory of individual species. This feedback loop, where evolutionary and ecological changes reciprocally affect one another, is a central tenet of eco-evolutionary dynamics. However, most work on such dynamics in natural populations has focused on one-way causal associations between ecology and evolution. Hence, direct empirical evidence for eco-evolutionary feedback is rare and limited to laboratory or mesocosm experiments. Here, we show in the wild that eco-evolutionary dynamics in a plant-feeding arthropod community involve a negative feedback loop. Specifically, adaptation in cryptic coloration in a stick-insect species mediates bird predation, with local maladaptation increasing predation. In turn, the abundance of arthropods is reduced by predation. Here, we experimentally manipulate arthropod abundance to show that these changes at the community level feed back to affect the stick-insect evolution. Specifically, low-arthropod abundance increases the strength of selection on crypsis, increasing local adaptation of stick insects in a negative feedback loop. Our results suggest that eco-evolutionary feedbacks are able to stabilize complex systems by preventing consistent directional change and therefore increasing resilience.