Interactions between stochastic and deterministic processes in stream fish community assembly

1993 ◽  
Vol 36 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Elizabeth M. Strange ◽  
Peter B. Moyle ◽  
Theodore C. Foin
Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 591
Author(s):  
Wensong Zhou ◽  
Yuxin Zhang ◽  
Shuang Zhang ◽  
Basil N. Yakimov ◽  
Keming Ma

Explaining community assembly mechanisms along elevational gradients dominated by deterministic processes or stochastic processes is a pressing challenge. Many studies suggest that phylogenetic and functional diversity are significant indicators of the process. In this study, we analyzed the structure and beta diversity of phylogenetic and functional traits along an elevational gradient and discussed the effects of environmental and spatial factors. We found that the phylogenetic and functional traits showed inconsistent changes, and their variations were closely related to the abiotic environment. The results suggested that the community assembly of woody plants was obviously affected by the combined effect of deterministic processes and the stochastic hypothesis (primarily by the latter). Phylogenetic and functional traits had a certain relationship but changed according to different rules. These results enhance our understanding of the assembly mechanism of forest communities by considering both phylogenetic and functional traits.


2020 ◽  
Author(s):  
Qing-Lin Chen ◽  
Hang-Wei Hu ◽  
Zhen-Zhen Yan ◽  
Chao-Yu Li ◽  
Bao-Anh Thi Nguyen ◽  
...  

Abstract Background: Termites are ubiquitous insects in tropical and subtropical habitats, where they construct massive mounds from soil, their saliva and excreta. Termite mounds harbor an enormous amount of microbial inhabitants, which regulate multiple ecosystem functions such as mitigating methane emissions and increasing ecosystem resistance to climate change. However, we lack a mechanistic understanding about the role of termite mounds in modulating the microbial community assembly processes, which are essential to unravel the biological interactions of soil fauna and microorganisms, the major components of soil food webs. We conducted a large-scale survey across a >1500 km transect in northern Australia to investigate biogeographical patterns of bacterial and fungal community in 134 termite mounds and the relative importance of deterministic versus stochastic processes in microbial community assembly. Results: Microbial alpha (number of phylotypes) and beta (changes in bacterial and fungal community composition) significantly differed between termite mounds and surrounding soils. Microbial communities in termite mounds exhibited a significant distance-decay pattern, and fungal communities had a stronger distance-decay relationship (slope = -1.91) than bacteria (slope = -0.21). Based on the neutral community model (fitness < 0.7) and normalized stochasticity ratio index (NST) with a value below the 50% boundary point, deterministic selection, rather than stochastic forces, predominated the microbial community assembly in termite mounds. Deterministic processes exhibited significantly weaker impacts on bacteria (NST = 45.23%) than on fungi (NST = 33.72%), probably due to the wider habitat niche breadth and higher potential migration rate of bacteria. The abundance of antibiotic resistance genes (ARGs) was negatively correlated with bacterial/fungal biomass ratios, indicating that ARG content might be an important biotic factor that drove the biogeographic pattern of microbial communities in termite mounds. Conclusions: Deterministic processes play a more important role than stochastic processes in shaping the microbial community assembly in termite mounds, an unique habitat ubiquitously distributed in tropical and subtropical ecosystems. An improved understanding of the biogeographic patterns of microorganisms in termite mounds is crucial to decipher the role of soil faunal activities in shaping microbial community assembly, with implications for their mediated ecosystems functions and services.


mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Lu Luan ◽  
Chao Liang ◽  
Lijun Chen ◽  
Haotian Wang ◽  
Qinsong Xu ◽  
...  

ABSTRACT Soil microbial community assembly is crucial for understanding the mechanisms of microbial communities that regulate ecosystem-level functioning. The relative contributions of stochastic and deterministic processes to microbial community assembly remain poorly defined, and major questions exist concerning the soil organic carbon (SOC) dynamics of microbial community assembly in deep soil. Here, the bacterial community assembly processes were explored across five soil profile depths (up to 80 cm) during a 15-year field experiment involving four fertilization regimes. We found that the bacterial community assembly was initially governed by deterministic selection in topsoil but was progressively structured by increasing stochastic dispersal with depth. The migration rate (m) and β-null deviation pattern supported the hypothesis of a relatively greater influence of dispersal in deep soil, which was correlated with bacterial community assembly by stochastic processes. These changes in the entire community assembly reflected consistent assembly processes of the two most dominant phyla, Acidobacteria and Chloroflexi. Structural equation modeling showed that soil features (pH and total phosphorus) and bacterial interactions (competition and network complexity) were significantly related to bacterial community assembly in the 0-to-10-cm and 10-to-20-cm layers. Partial Mantel tests, structural equation modeling, and random forest modeling consistently indicated a strong and significant correlation between bacterial community assemblages and SOC dynamics, implying that bacterial assembly processes would potentially suppress SOC metabolism and mineralization when the contributions of stochastic dispersal to communities increased in deeper layers. Our results have important implications for integrating bacterial community assembly processes into the predictions of SOC dynamics. IMPORTANCE We have provided a framework to better understand the mechanisms governing the balance between stochastic and deterministic processes and to integrate the shifts in community assembly processes with microbial carbon metabolism. Our study reinforced that environmental filtering and bacterial cooccurrence patterns influence the stochastic/deterministic continuum of soil bacterial community assembly and that stochasticity may act through deeper soil layers to influence carbon metabolism. Delineating theoretically the potential linkages between community assembly and SOC dynamics across a broad range of microbial systems represents an interesting topic for future research.


mSystems ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Cui-Jing Zhang ◽  
Jie Pan ◽  
Chang-Hai Duan ◽  
Yong-Ming Wang ◽  
Yang Liu ◽  
...  

ABSTRACT Mangroves, as a blue carbon reservoir, provide an environment for a variety of microorganisms. Mangroves lie in special locations connecting coastal and estuarine areas and experience fluctuating conditions, which are expected to intensify with climate change, creating a need to better understand the relative roles of stochastic and deterministic processes in shaping microbial community assembly. Here, a study of microbial communities inhabiting mangrove sediments across southeastern China, spanning mangroves in six nature reserves, was conducted. We performed high-throughput DNA sequencing of these samples and compared them with data of 1,370 sediment samples collected from the Earth Microbiome Project (EMP) to compare the microbial diversity of mangroves with that of other biomes. Our results showed that prokaryotic alpha diversity in mangroves was significantly higher than that in other biomes and that microbial beta diversity generally clustered according to biome types. The core operational taxonomic units (OTUs) in mangroves were mostly assigned to Gammaproteobacteria, Deltaproteobacteria, Chloroflexi, and Euryarchaeota. The majority of beta nearest-taxon index values were higher than 2, indicating that community assembly in mangroves was better explained through a deterministic process than through a stochastic process. Mean annual precipitation (MAP) and total organic carbon (TOC) were main deterministic factors explaining variation in the microbial community. This study fills a gap in addressing the unique microbial diversity of mangrove ecosystems and their microbial community assembly mechanisms. IMPORTANCE Understanding the underlying mechanisms of microbial community assembly patterns is a vital issue in microbial ecology. Mangroves, as an important and special ecosystem, provide a unique environment for examining the relative importance of stochastic and deterministic processes. We made the first global-scale comparison and found that microbial diversity was significantly different in mangrove sediments compared to that of other biomes. Furthermore, our results suggest that a deterministic process is more important in shaping microbial community assembly in mangroves.


2015 ◽  
Vol 25 (3) ◽  
pp. 322-335 ◽  
Author(s):  
Mitsuru Ohira ◽  
Hiroshi Tsunoda ◽  
Kazuya Nishida ◽  
Yoshito Mitsuo ◽  
Yutaro Senga

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