Environmental fluctuations reshape an unexpected diversity-disturbance relationship in a microbial community

Abstract

Environmental disturbances have long been theorized to shape the diversity and composition of ecosystems. However, fundamental limitations in our ability to specify the scale and features of a disturbance in the field and laboratory have produced an inconsistent picture of diversity-disturbance relationships (DDRs). Using a recently developed automated continuous culture system, we decomposed a dilution disturbance into intensity and fluctuation components, and tested their effects on diversity of a soil-derived bacterial community across hundreds of replicate cultures. We observed an unexpected U-shaped relationship between diversity and disturbance intensity in the absence of fluctuations, counter to classic intuition. Adding fluctuations erased the U-shape and increased community diversity across all disturbance intensities. All of these results are well-captured by a Monod consumer resource model, and can be explained by a novel “niche flip” mechanism wherein tradeoffs between species growth parameters produce coexistence regimes that collapse at intermediate disturbance levels. Our results illustrate that compositional complexity of an ecosystem can be generated and predictably reshaped using temporal environmental patterns, and highlight how distinct features of disturbance can interact in complex ways to govern ecosystem assembly.

Microbial Potlatch: Cell-level adaptation of leakiness of metabolites leads to resilient symbiosis among diverse cells

“…Of note, the existence of waste byproducts and inhibitory chemicals, which was not assumed, could lead to greater diversity under nutrient-rich environments, as greater nutrient supply will increase the waste byproducts ( Pfeiffer and Bonhoeffer, 2004; Marsland III et al, 2019 ). Indeed, the actual relationship between diversity and resource availability is sometimes non-monotonous ( Claire Horner-Devine et al, 2003; Mancuso et al, 2020 ) and can depend on the cultivation conditions ( Zhou et al, 2002 ). This complex relationship may be a consequence of the competing effects of essential metabolites and waste byproducts.…”

Resistance potential of soil bacterial communities along a biodiversity gradient in forest ecosystems

“…Global climate changes are causing shifts in the richness, distribution range, and composition of species worldwide and affecting ecological stability and the sustainability of ecosystem functions 14 . How environmental disturbance influences microbial biodiversity has been broadly addressed 33–35 . Nevertheless, how biodiversity reflects the potential of community‐level resistance is far from clear.…”

Adaptation of metabolite leakiness leads to symbiotic chemical exchange and to a resilient microbial ecosystem

“…Note here that the existence of wasteful or inhibitory byproducts, which was not assumed in our simulations, could lead to greater diversity under nutrient-rich environments, as nutrient excess will increase the waste byproducts [ 64 , 65 ]. Indeed, the actual relationship between diversity and resource availability is sometimes non-monotonous [ 66 , 67 ] and can depend on the cultivation conditions [ 60 ]. This complex relationship may be a consequence of the competing effects of essential metabolites and waste byproducts.…”