Thursday, November 16, 2023
11:00 - 12:00
I will discuss a recent paper https://onlinelibrary.wiley.com/doi/full/10.1111/jeb.14158 where I investigated whether fluctuating nutrients can (partly) explain diversity observed in microbial communities, such as oceans or the human gut. When nutrient levels fluctuate over time, one possibly relevant mechanism is coexistence between specialists on low and specialists on high nutrient levels. The relevance of this process is supported by the observations of coexistence in the laboratory, and by simple models, which show that negative frequency dependence of two such specialists can stabilize coexistence. However, as microbial populations are often large and fast growing, they evolve rapidly. I will discuss how we determine what happens when species can evolve; whether evolutionary branching can create diversity or whether evolution will destabilize coexistences. We derive an analytical expression of the invasion fitness in fluctuating environments and use adaptive dynamics techniques to find that evolutionarily stable coexistence requires a special type of trade-off between growth at low and high nutrients.
I will also discuss current work on a different mechanism: When one phenotype degrades a toxin which allo another phenotype to grow (cross-protection) and ideas how to generalize results from both of these studies to study the interaction of more mechanisms in larger networks.
Dutch Institute for Emergent Phenomena (DIEP)
computational physics, emergence, mathematical physics