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Talk by Bram van Dijk

Bram van Dijk

Title: "Black queen dynamics: an evolutionary race to the bottom?"
Occasion: SFB Special Seminar
Host: Christian Kost
Start: 05.07.2022 - 11:15
Location: CellNanOs 38/201 

About the speaker: Dr. Bram van Dijk conducts research at the Max Planck Institute for Evolutionary Biology in Plön.

Abstract of the talk: Eukaryotic cells contain membrane-bounded organelles to separate distinct cellular functions. Microorganisms often live in dense communities, where there is strong competition for limited resources. While resource scarcity drives the evolution of aggressive strategies, such as chemical or mechanical weapons to kill competitors, these negative interactions are only part of the puzzle. For example, positive interactions occur when one species feeds off the by-products or public goods produced by another. Such interactions could even be bi-directional in nature, meaning that both parties grow better in the presence of the other. The processes by which mutual dependencies evolve through the availability of public goods, are referred to as "black queen dynamics". Unstopped, black queen dynamics could give rise to an evolutionary race to the bottom; a state where the production of public goods is minimised. What are the potential forces that can prevent this evolutionary race to the bottom?

In my talk, I will discuss computational models that explore the evolution of mutual dependencies in microbial communities. First, I will discuss how evolving virtual metabolic networks can indeed give rise to strong metabolic interdependencies, but this outcome is not set in stone. Instead, historical "frozen accidents" in evolved metabolic networks predestine some populations to develop into cross-feeding communities, while others remain self-sufficient. This result highlights how evolution itself can attain states where dependencies are not favoured. Next, I will discuss preliminary results of two more recent modelling projects where we dive deeper into the processes that may prevent the evolutionary race to the bottom. First I will show how non- producing phenotypes can pause black queen dynamics, a process that is shaped by interaction range and neighbourhood uncertainty. Finally, I will illustrate how community-level selection can result in a reduction of mutual dependencies, a process that is driven by community collapse and recolonisation of available niche space. In summary, while all models illustrate a strong potential to develop mutual dependencies through black queen dynamics, other processes can halt or even entirely prevent an evolutionary race to the bottom.