Contextual eco-evolutionary dynamics in the stick insect Timema cristinae
Interest in evolution as an ecological process continues to grow. Field experiments using the stick insect Timema cristinae showed how the evolution of camouflage (mal)adaptation can structure plant-dwelling arthropod communities, whereby poorly camouflaged Timema lead to reduced arthropod abundance and diversity. Although these experiments were highly natural, observational evidence that (mal)adaptation structures wild arthropod communities would argue strongly for the importance of eco-evolutionary dynamics in this system.
To address this gap, we performed a observational study of a wild arthropod metacommunity and related natural levels of camouflage (mal)adaptation to arthropod community properties. In addition, we evaluated the roles of patch connectivity, patch size, host-plant species, plant genetics, and plant chemistry.
Our observations show a positive relationship between camouflage maladaptation and both arthropod abundance and diversity. This result is discordant with previous experiments, but is consistent with a recently discovered eco-evolutionary feedback in T. cristinae, implicating negative density-dependent selection by avian predators.
These findings suggest that community-level eco-evolutionary dynamics are contextual in T. cristinae, exhibiting different mechanisms under different conditions, but that evolution nevertheless has profound consequences for communities. Future work will test hypotheses about the contrasting results to determine the specific nature of contingency for eco-evolutionary dynamics in this system.