Self-organization and criticality in spatially coupled ecosystems

• Applicant: Dr. Jonas Denk
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics ; Biophysics
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445916943

• Final Report Year: 2025

Final Report Abstract

The ecological dynamics of a community is shaped by the interplay of numerous factors, including inter- and intra-species interactions, speciation and species immigration. Finding meaningful theoretical models for the assembly and the stability of ecosystems is further complicated by the overwhelming number of species typically found in natural ecosystems. One of my key research goals as a DFG fellow was to develop a mathematical framework to investigate the self-organization process of species-rich metacommunities. I developed a mathematical theory to study metacommunities of (infinitely) many species, which I applied to different ecologically relevant scenarios including competitive and mutualistic interactions between species. Based on my combined analytical and numerical solutions of this theory, I was able to derive key mechanisms that allowed me to make predictions on characteristic patterns and the dynamics in spatially extended metacommunities. In addition to studying the ecological dynamics of metacommunities in theory I performed extensive experimental research on the interaction between evolutionary processes and ecological dynamic in communities of E.coli. By means of genetic engineeing and daily dilution experiments of different E.coli strains, I was able to characterize diversification events, in which an E. coli strain diversified into two phenotypes, which interact with each other in a symbiotic manner based on the structure of their diauxic shifts during population growth. In conclusion, during my period as DFG fellow, I studied effects of ecological as well as evolutionary drivers of complex ecological systems and could contribute significantly to a better understanding of ecosystems, including their manipulation and preservation.

Publications

• Chaos may lurk under a cloak of neutrality. Proceedings of the National Academy of Sciences, 117(28), 16104-16106.
  Denk, Jonas; Martis, Stephen & Hallatschek, Oskar
  
• Self-consistent dispersal puts tight constraints on the spatiotemporal organization of species-rich metacommunities. Proceedings of the National Academy of Sciences, 119(26).
  Denk, Jonas & Hallatschek, Oskar
  
• Rediversification following ecotype isolation reveals hidden adaptive potential. Current Biology, 34(4), 855-867.e6.
  Ascensao, Joao A.; Denk, Jonas; Lok, Kristen; Yu, QinQin; Wetmore, Kelly M. & Hallatschek, Oskar
  
• Tipping points emerge from weak mutualism in metacommunities. PLOS Computational Biology, 20(3), e1011899.
  Denk, Jonas & Hallatschek, Oskar