Species coexistence through gleaner-opportunist trade-offs in structurally, spatially and evolutionarily extended communities

• Applicant: Dr. Toni Klauschies
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 516585050

For decades community ecology has been seeking to understand the mechanisms that underlie the astonishing diversity of species observed in natural systems. Some of the proposed mechanisms, such as feeding on different resources, allow different species to coexist under constant environmental conditions, while others, such as relative non-linearity, rely on temporal variation in the environmental conditions. The latter mechanism allows two consumers to coexist on a single fluctuating resource if they show substantial differences in the curvature of their functional responses (i.e., relative non-linearity). This usually implies that one consumer (the gleaner) grows better at lower resource densities whereas the other consumer (the opportunist) performs better at higher resource densities. Species coexistence through relative non-linearity has been extensively studied in simple consumer-resource systems. However, we do not have a clear expectation about its relevance in more complex, natural ecological systems where consumer-resource interactions are embedded in more complex food-web structures and modified by both spatial dynamics and eco-evolutionary feedbacks. In order to assess the relevance of relative non-linearity for consumer coexistence, it is therefore important to determine how it interacts with these different processes. With this proposal I aim to study three different generic mechanisms that are expected to influence the temporal variation of the resource abundance and the overall mortality of the consumers and thereby the likelihood of consumer coexistence through relative non-linearity. The main objectives are:1) To determine the conditions under which relative non-linearity promotes consumer coexistence in structurally more complex and realistic food web models, which may for example comprise an additional predator that indiscriminately feeds on the two different consumers.2) To investigate how spatio-temporal variation in the size of the resource population due to self-organized pattern formation in metacommunities affects consumer coexistence through relative non-linearity. 3) To evaluate whether rapid evolution in the resource may promote consumer-resource oscillations that allow consumers coexistence through relative non-linearity that would be otherwise impossible. The planned investigations thus cover a wide spectrum of additional mechanisms, related to highly active and topical areas of ecological research. Understanding how these mechanisms interact with coexistence through relative non-linearity will be critical for assessing its relevance in shaping diversity in complex natural communities.

• DFG Programme: Research Grants