Project Details
Projekt
Towards a process-based understanding of context-dependent forms of symbioses
Applicants
Professorin Dr. Ursula Gaedke; Dr. Toni Klauschies
Subject Area
Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 528028597
A symbiosis represents a close physical association of individuals from different species, which may have positive, negative or no effects on the fitness of both partners, resulting in e.g. mutualism, parasitism or commensalism. Such forms of symbiosis have been considered as fixed among distinct species pairs but recent evidence reveals that the form of symbiosis may change in response to altered abiotic or biotic conditions, making the form of symbiosis context dependent. However, we currently lack a clear mechanistic understanding of the various factors influencing the cost-benefit relationships for both symbiotic partners in a food web context. Hence, we aim to gain novel and general insights into how the form of symbiosis depends on the densities, relative frequencies and traits of the symbiosis partners, and how the form of symbiosis influences the population and trait dynamics and the feedback between the form of symbiosis and trait and population dynamics. This will contribute to general theory building in community ecology by combining the frameworks of context-dependent symbiosis, eco-evolutionary dynamics and food web theory. Therefore, we will implement mathematical models that account for the context-dependent cost-benefit relationships of a ciliate-algae symbioses. More specifically, (i) we want to develop and analyse a basic food web model to reveal general processes underlying context-dependent changes in the strength and form of a symbiosis under different environmental conditions such as light, nutrients and bacteria. (ii) We will extend this basic food web model to allow individual organisms, in particular the host and the algal endosymbiont, to adjust their functional properties to changing conditions and to determine the effect of this flexibility on the population dynamics and the form of symbiosis. Furthermore, (iii) we want to extend the basic food web model and investigate the separate and joint effects of an additional grazer for the algae and/or ciliates and/or another algal competitor for the free-living symbiont on the cost-benefit relationships and thus the form of symbiosis and the corresponding trait and population dynamics. Finally, (iv) we will evaluate how we can reduce the complexity of the basic food web model in order to develop a more general food web module that can be used to study context-dependent changes in the costs and benefits of symbiosis in larger and more complex food webs and to abstract from the distinct system under consideration. We will link our model development, parametrization and analysis firmly to empirically well-studied systems within the research unit. This will determine the required degree of complexity, e.g. in resolving mechanistic details regulating the stoichiometry of the endosymbiotic algae. In turn, our model will help to mechanistically understand experimental data and to guide experimental designs.
DFG Programme
Research Units
