Heating up trophic interactions in a pond: from plastic and evolutionary single-species responses to food-web stability

The earth is heating up and there is growing concern for the local persistence of populations. An increasing number of studies indicates that organisms can develop both plastic (within a generation) and evolutionary (genetic) trait changes to deal with higher mean temperatures. Much less attention went to how these direct effects of mild warming may have cascading effects on species interactions and food-web stability, which may be more important for population persistence. Moreover, besides increases in mean temperatures, which may be beneficial, organisms will experience increases in daily temperature variation and in extreme temperatures which may have a stronger and even opposite effect on organisms. We will address how both increases in temperature means, variation and extremes shape trait values (both through plastic and evolutionary responses) in both predator and prey and how this translates into changed interactions in a simple pond food web consisting of damselfly predators, water fleas and green algae. First, we will focus on ecologically relevant trait changes along a broad temperature gradient and compare this between predator and prey populations differing in thermal adaptation. Second, we will study the underlying changes in gene expression to better understand these trait changes. Finally, we will combine experiments with modelling to test how thermal regimes shape the strength of species interactions and the long-term stability of this simple pond food web.