Structured environments foster competitor coexistence by manipulating interspecies interfaces

Abstract

Natural environments, like soils or the mammalian gut, frequently contain microbial consortia competing within a niche, wherein many species contain genetically encoded mechanisms of interspecies competition. Recent computational work suggests that physical structures in the environment can stabilize local competition between species that would otherwise be subject to competitive exclusion under isotropic conditions. Here we employ Lotka-Volterra models to show that interfacial competition localizes to physical structures, stabilizing competitive ecological networks of many species, even with significant differences in the strength of competitive interactions between species. Within a limited range of parameter space, we show that for stable communities the length-scale of physical structure inversely correlates with the width of the distribution of competitive fitness, such that physical environments with finer structure can sustain a broader spectrum of interspecific competition. These results highlight the potentially stabilizing effects of physical structure on microbial communities and lay groundwork for engineering structures that stabilize and/or select for diverse communities of ecological, medical, or industrial utility.

Biofilm cultivation facilitates coexistence and adaptive evolution in an industrial bacterial community

“…Coexistence requires niche differentiation that increases intraspecific competition, so it becomes stronger than interspecific competition 7 . Introduction of a structured environment can generate distinct niches, and hence lead to coexistence and increased diversity 5 , 6 , 8 .…”

The Coexistence of Bacterial Species Restructures Biofilm Architecture and Increases Tolerance to Antimicrobial Agents

“…The principle of competitive exclusion asserts that the adaptive capacity of species to a niche defines its reproduction rates and consequently leads to the dominance or exclusion of the species in multispecies biofilms ( 8 ). E. faecalis has a strong adaptive capacity, characterized by persistence in different environments and typical metabolic flexibility ( 36 ).…”

“…The factors affecting multispecies biofilm succession are currently believed to include environmental variability, social interactions (including but not limited to the classic “rock-paper-scissors” strategy for spatial colonization, cross-feeding, and metabolic trade-off), and local spatial organization ( 7 , 8 ). Of these, the latter two are critical to the stability of multispecies communities and are involved in maintaining the diversity of competing ecosystems ( 8 ). In addition, multispecies biofilms typically exhibit various spatial structures, such as mixed cell lineages, segregated microcolonies, and layered structures ( 9 , 10 ).…”

Mutualism Destabilizes Communities, but Competition Pays the Price

“…However, this effect was less pronounced at higher species richness. Our study neglects environmental or spatial heterogeneity, which is known to affect coexistence and stability (Allen et al, 2013;Durrett and Levin, 1994;Gordon et al, 2015;Hauert and Doebeli, 2021;Krakauer and Pagel, 1995;Stein et al, 2014;Ursell, 2021;Yu et al, 2001). Another factor that can potentially affect community stability is demographic stochasticity, which has been shown to promote mutualism/cooperation in many model systems (Chotibut and Nelson, 2015;Constable et al, 2016;Houchmandzadeh, 2015;Houchmandzadeh and Vallade, 2012;McLeod and Day, 2019).…”