Changes in assembly processes in soil bacterial communities following a wildfire disturbance

Abstract

Although recent work has shown that both deterministic and stochastic processes are important in structuring microbial communities, the factors that affect the relative contributions of niche and neutral processes are poorly understood. The macrobiological literature indicates that ecological disturbances can influence assembly processes. Thus, we sampled bacterial communities at 4 and 16 weeks following a wildfire and used null deviation analysis to examine the role that time since disturbance has in community assembly. Fire dramatically altered bacterial community structure and diversity as well as soil chemistry for both time-points. Community structure shifted between 4 and 16 weeks for both burned and unburned communities. Community assembly in burned sites 4 weeks after fire was significantly more stochastic than in unburned sites. After 16 weeks, however, burned communities were significantly less stochastic than unburned communities. Thus, we propose a three-phase model featuring shifts in the relative importance of niche and neutral processes as a function of time since disturbance. Because neutral processes are characterized by a decoupling between environmental parameters and community structure, we hypothesize that a better understanding of community assembly may be important in determining where and when detailed studies of community composition are valuable for predicting ecosystem function.

Prokaryotic Communities in Pit Mud from Different-Aged Cellars Used for the Production of Chinese Strong-Flavored Liquor

“…The loss in diversity and species richness had likely resulted from niche selection and the filtering out of species that could not tolerate the pit-mud environment. Although we did not investigate the prokaryotic community composition of parental soil used for the preparation of pit mud in this study, many studies have revealed that the bacterial community in aerobic soil is mainly composed of Acidobacteria, Actinobacteria, Proteobacteria, Bacteroidetes, and Firmicutes (19,20). However, the pit-mud prokaryotic community was dominated by phylum Firmicutes (95.7%) after 1-year of domestication.…”

“…The balance of NH 4 ϩ and fatty acid content may influence pH directly and, indirectly, the prokaryotic community structure. Niche-driven changes in the pit-mud prokaryotic community supported that environmental factors, not historical factors, determine the shift in the structure of a prokaryotic community (20,25) in the pit mud.…”

Effects of dispersal and selection on stochastic assembly in microbial communities

“…Because microbes have high dispersal rates, large population sizes, fast growth rates and a propensity for dormancy, communities were traditionally thought to assemble deterministically. However, recent characterizations of microbial communities provide evidence that in addition to environmental selection, stochastic processes can be important drivers of microbial community assembly (Ferrenberg et al, 2013;Nemergut et al, 2013;Zhou et al, 2013;Fukami, 2015).…”

Quantifying the relative roles of selective and neutral processes in defining eukaryotic microbial communities

“…A better understanding of the factors underpinning community structure also ensures greater accuracy for predictions concerning both species conservation and communities' fates under various environmental change scenarios (Fierer et al, 2003;Lennon and Jones, 2011;Ferrenberg et al, 2013). Differences in the types and abundances of species in space may arise through both natural-selection-driven and non-selection driven processes, which are directly analogous to classic population genetic processes operating within species (Nemergut et al, 2013).…”