What do metabolic constraints inform us about the emergence of early stable bacterial communities?

Stability of an ecosystem is determined by its composition. As a system gains stability, one of the major trends observed during ecological succession, which refers to the development of a community, is an increase in compositional diversity [1]. It has been shown that multispecies systems can support a larger community with more surviving species at steady state when the variability across pairwise coupling strengths between species is smaller [2]. But how a small system with one species and no foreign invaders develops into a large diverse system remains an open question. Here, we consider the stability of a system under constant nutrient flux [3] when a species is competing with its closely related mutants to understand how early diversity is established. Using adiabatic approximation and discarding higher order terms, we recover the reduced dynamics for chemostats similar to Lotka-Volterra systems. By introducing small perturbations to the growth rates of the otherwise identical species constrained by rates of metabolic regulations, the rules for obtaining stable multispecies communities are obtained.

[1] E. P. Odum, Science 164, 262 (1969).
[2] G. Bunin, Physical Review E 95, (2017).
[3] A. Novick and L. Szilard, Proceedings of the National Academy of Sciences 36, 708 (1950).