Fig. 4: Continuous time simulations highlight the interplay of slow community dynamics and fast resource dynamics in a cross-feeding system.

a Simulations of auxotroph abundance (top) and resource concentration (bottom) for a set of chemostat parameters where \(D=0.2\), \({R}_{1,{in}}=1\), \({R}_{2,{in}}=1\), and \({R}_{3,{in}}=11.11\). The auxotroph parameters were simplified and made to be symmetrical for illustrative purposes (Supplementary Table 1). Colored bars between the plots of abundance and resource dynamics show the intervals of glucose and amino acid limitation for each auxotroph. Shading within the plots highlights distinct types of resource limitation and interaction topologies. In the light gray regions, one auxotroph is amino acid limited while the other is glucose limited. In the dark gray regions, both auxotrophs are amino acid limited. b Population cycles and associated changes in the community interaction network. Each network diagram represents a snapshot of the system at the time indicated in (a) with a numeral (i-iv). Solid lines with arrowheads represent positive interactions, i.e., amino acid promoting the growth of either auxotroph. Dashed lines with flatheads represent inhibitory interactions. Coloring of the interaction lines represents active (black) or inactive (gray) interactions. Shading around the interaction networks corresponds with the shading from (a), where light gray network diagrams represent slow community dynamics and dark gray diagrams represent fast resource dynamics.