Trophic cascades alter eco-evolutionary dynamics and body size evolution

Trait evolution in predator-prey systems can feed back to the dynamics of interacting species as well as cascade to impact the dynamics of indirectly linked species (eco-evolutionary trophic cascades; EETC). A key mediator of trophic cascades is body mass, as it both strongly influences and evolves in response to predator-prey interactions. Here we use Gillespie Eco-Evolutionary Models to explore EETCs resulting from top predator loss and mediated by body mass evolution. Our four trophic level food chain model uses allometric scaling to link body mass to different functions (ecological pleiotropy) and is realistically parameterized from the FORAGE database to mimic the parameter space of a typical freshwater system. To track real-time changes in selective pressures, we also calculated fitness gradients for each trophic level. As predicted, top predator loss generated alternating shifts in abundance across trophic levels, and depending on the nature and strength in changes to fitness gra...