Evolutionary rescue in complex communities

• Applicant: Dr. Ellen van Velzen
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Bioinformatics and Theoretical Biology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449580717

Environmental change may drive species extinct; but evolutionary rescue (ER) of a species may occur if it can adapt rapidly enough to the new conditions. While ER has been extensively studied in single-species contexts, very little is known on ER when species are embedded in a larger community such as a food web, interacting with prey, predators and competitors.Rapid evolution is often found in traits mediating predator-prey interactions: defensive traits in prey and offensive traits in predators. These traits are especially relevant in a community context and thus provide an important avenue for ER, but are largely ignored by current theory. Moreover, rapid evolution in such traits can feed back on ecological dynamics, so that evolutionary change in a single species may have indirect effects that ripple through an entire community. Such eco-evolutionary feedbacks are expected to be of great importance for ER in complex communities, but this is almost entirely unstudied.With this project I aim to develop new theory on ER comprising the mechanisms for and effects of ER in food webs ranging in size from small (4 species) to large (20-50 species). The main objectives are:1. To gain a detailed understanding of how species interactions shape ER in small food webs. The dynamics of all species can here be understood in detail, and we can achieve a mechanistic understanding of the processes driving ER. Particular focus will be on the possible role of indirect evolutionary rescue, where a species is rescued by evolution in a different species.2. To quantify how many species in a food web should evolve in order for ER to be most effective. Contrary to intuitive expectation, ER may be most effective when only one species evolves, but this has not been investigated beyond linear food chains.3. To scale up the insights derived from small food webs to larger, ecologically relevant food webs. Here the main focus is on the role of food web size and connectance for ER, as indirect effects are expected to be strongest in large, well-connected food webs.4. To identify potential “keystone adapters”: species whose evolution is important to the rescue of other species and maintenance of the food web. Which species properties (traits or position in the food web) make a species into a keystone adapter is one of the most important questions to be answered.To achieve these goals, the well-established adaptive dynamics framework for modelling rapid evolution will be combined with recent approaches for disentangling eco-evolutionary feedbacks, and with existing approaches for modelling the dynamics of large food webs. The anticipated results will give the first insights into ER in natural communities, and how it is shaped by species interactions and eco-evolutionary feedbacks. By showing how important interspecific interactions are to ER, this project will help revolutionize ER research which is still almost entirely focused on a single-species context.

• DFG Programme: Research Grants