CANCELLED - Does adaptation maintain weak interactions in ecological foodwebs?

Background/Question/Methods Much attention has been given lately to the importance of weak interactions for the stability of differently structured foodwebs. Evidence suggests that these weak interactions are indeed abundant and crucial for the sustainability of ecological complex systems. However, when one recalls that ecological systems comprise mortal individuals that undergo adaptation, a fundamental question arises: how are weak interactions maintained in ecological systems? is it because less stable ecological system will be replaced by a more stable system or is there anything intrinsic in ecological interactions that favorizes the presence of weak interactions? In natural systems the time scales of ecological interactions and evolutionary change can be mixed ,moreover, high plasticity of certain traits may cause rapid adaptation of a population to changing environment without the need of evolutionary times. In order to address the how weak interactions are maintained we incorporate the formalism of adaptive dynamics into established food web models.
Results/Conclusions

We study models of three interactions motifs present in many foodwebs: Intra-guild predation, diamond shape (one predator, two consumers that feed on one resource) and one super predator which couples two consumer-resource systems. Each system can express diverse dynamic features (depending upon parameters) including fixed points, limit cycles and chaotic attractors. Using two adaptive dynamics techniques we show that adaptation of the predator’s preference for resource types results in a mean preference parameter that balances interaction strengths, lessening the effectiveness of weak interactions. Moreover, we show that the selected preference doesn't always reflect the maximum density of the predator and or the maximum per capita growth rate (especially when the ecological dynamics does not support fixed point attractor). Furthermore, we observe significant deviations in the dynamics when one considers a uniform population with a universal trait value and a small invader and a diverse population with a small invader. The fact that the result of evolution of the predators does not create weak interactions raises the question of exactly how these links are maintained in nature.