Prof. Mikhail Tikhonov

Physics Department

Washington University in St Louis

Performance tradeoffs and eco-evolutionary interplay at high diversity

Much of our understanding of ecological and evolutionary mechanisms derives from analysis of low-dimensional models: with few interacting species, or few axes defining fitness. It is not always clear to what extent such low-dimensional intuition applies to the complex, high-dimensional reality. This becomes especially relevant in the microbial context, because most naturally occurring communities harbor a strikingly large number of coexisting species. In the first part of the talk, I will describe how extending Tilman's geometric intuition into high dimensions offers insights into eco-evolutionary interplay in high-diversity ecosystems, revealing the existence of multiple qualitatively distinct dynamical regimes. Which of these regimes is realized is determined by the structure of performance tradeoffs constraining the system. Importantly, such tradeoffs, which most models simply postulate as part of a "fitness landscape", are known to themselves evolve. In the second part of the talk, I will briefly describe how an ecologically-inspired model provides a promising theoretical context for patching this gap in evolutionary theory.