Key Community Assembly Processes Switch between Scales in Shaping Beta Diversity in Two Primary Forests, Southwest China

Environmental and dispersal-based processes have been widely investigated for the understanding of community assembly. However, the relative importance of these ecological processes across spatial scales, life history stages and forest types needs to be largely studied. We test the variability of ecological processes in shaping tree community composition across life stages and spatial scales, and in particular, the hypothesis that dispersal limitation dominates at smaller scales and early life stages, but environmental filtering at larger scales and later life stages. We used spatially explicit point process models to estimate the relative importance of environmental and dispersal processes and their combined effect on beta diversity across spatial scales and life stages in tropical and subtropical forests. These models fit the observed species distribution pattern and generated realizations of the fitted models for each species. We found that the importance of environmental and dispersal processes did not shift with life stages or vegetation types, but did with spatial scales. Dispersal provided the best explanation of large-scale patterns, but dispersal combined with environmental selection was superior for small-scale patterns. In conclusion, we confirm the importance of spatial scale for the effects and identification of community assembly mechanisms. Our results also suggest that the importance of both dispersal and environmental processes for community assembly could be pervasive across life stages and vegetation types. The generality of these findings should be tested further in different vegetation types and life stages to assess whether specific ecological processes have consistent effects on community structure across life stages and vegetation types.

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Taxonomic Dependency of Beta Diversity for Bacteria, Archaea and Fungi in a Semi-Arid Lake

10.21203/rs.3.rs-1120535/v1 ◽

2021 ◽

Author(s):

Haijun Yuan ◽

Weizhen Zhang ◽

Huaqun Yin ◽

Runyu Zhang ◽

Jianjun Wang

Keyword(s):

Water Depth ◽

Beta Diversity ◽

Species Turnover ◽

Environmental Drivers ◽

Ecological Processes ◽

Environmental Selection ◽

Community Variation ◽

Taxonomic Groups ◽

Semi Arid ◽

Total Beta

Abstract Microbial beta diversity has been recently studied along the water depth in aquatic ecosystems, however its turnover and nestedness components remain elusive especially for multiple taxonomic groups. Based on the beta diversity partitioning developed by Baselga and Local Contributions to Beta Diversity (LCBD) partitioning by Legendre, we examined the water-depth variations in beta diversity components of bacteria, archaea and fungi in surface sediments of Hulun Lake, a semi-arid lake in northern China, and further explored the relative importance of environmental drivers underlying their patterns. We found that the relative abundances of Proteobacteria, Chloroflexi, Euryarchaeota and Rozellomycota increased towards deep water, while Acidobacteria, Parvarchaeota and Chytridiomycota decreased. For bacteria and archaea, there were significant (P < 0.05) decreasing water-depth patterns for LCBD and LCBDRepl (i.e., species replacement), while increasing patterns for total beta diversity and turnover, implying that total beta diversity and LCBD were dominated by species turnover or LCBDRepl. Further, bacteria showed a strong correlation with archaea regarding LCBD, total beta diversity and turnover. Such parallel patterns among bacteria and archaea were underpinned by similar ecological processes like environmental selection. Total beta diversity and turnover were largely affected by sediment total nitrogen, while LCBD and LCBDRepl were mainly constrained by water NO2−-N and NO3−-N. For fungal community variation, no significant patterns were observed, which may be due to different drivers like water nitrogen or phosphorus. Taken together, our findings provide compelling evidences for disentangling the underlying mechanisms of community variation in multiple aquatic microbial taxonomic groups.

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The Relative Importance of Niche Process and Neutral Process in the Community Assembly of Subtropical Karst Forest: A Perspective on the Changes of Species Distribution Patterns at Different Scales

10.21203/rs.3.rs-1035471/v1 ◽

2021 ◽

Author(s):

Yan He ◽

Yong Jiang ◽

Hongling Lin ◽

Yuanfang Pan ◽

Shichu Liang ◽

...

Keyword(s):

Community Assembly ◽

Variation Partitioning ◽

Species Abundance ◽

Distribution Patterns ◽

Relative Importance ◽

Ecological Processes ◽

Abundance Pattern ◽

Karst Forest ◽

Neutral Processes ◽

Neutral Process

Abstract Background and aimsThe importance of niche processes and neutral processes to community assembly has been affirmed by most studies, although their relative importance needs to be determined in many systems. Moreover, as the spatial scale changes, the ecological processes that determine the community pattern may differ. We tested these ideas in subtropical karst forest in southwestern China in order to aid efforts of community reconstruction.MethodsTo test the importance of niche-based and neutral mechanisms we compared the fit six models to the observed SAD of the plot at three different sampling scales (10 m × 10 m, 20 m × 20 m, 50 m × 50 m). We also used spatial autocorrelation and distance-based Moran's eigenvector maps (dbMEM) combined with variation partitioning to further determine the relative contribution of the niche process and the neutral process under different sampling scales.ResultsThe neutral theoretical and statistical models fit the observed species abundance distribution curve best at each sampling scale. And variation partitioning showed that although the contribution of spatial structure was lower at larger sampling scales, it was still important, suggesting that neutral processes drive community structure at all sampling scales. In contrast, habitat filtering and interspecies competition may lead to a net weakening of the contribution of the niche process to the species abundance pattern of the community because they act in opposite directions. ConclusionsIn the restoration and reconstruction of local karst forest communities, environmental heterogeneity, inter-species relationships, and geographic spatial differences should all be considered.

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Patterns of diversity on the Paleozoic shelf: implications for controls on clade history

The Paleontological Society Special Publications ◽

10.1017/s2475262200008261 ◽

1992 ◽

Vol 6 ◽

pp. 266-266 ◽

Cited By ~ 1

Author(s):

J. John Sepkoski ◽

Arnold I. Miller

Keyword(s):

Beta Diversity ◽

Spatial Scales ◽

Alpha Diversity ◽

Physical Geography ◽

Local Communities ◽

Dominant Factor ◽

Ecological Processes ◽

Alpha And Beta Diversity ◽

Global Diversity ◽

Local Ecology

Global diversity often is treated as a barometer of evolutionary success of clades without reference to their occurrence in ecological or biogeographical space. But global diversity is a composite of various spatial scales: alpha diversity, the number of taxa co-occurring in local communities; beta diversity, the distinction in taxonomic composition among local communities; and gamma diversity, the distinction, or degree of endemism, among geographic provinces, It has been argued by some workers that global diversity correlates strongly with alpha (and beta) diversity but by others that provinciality is the principal control of global patterns. The distinction is important, implicating either ecological processes (“adaptation”) or physical geography (“contingency”) as the major factor in expansion of clades.We have examined the ecological half of this problem with a data base comprising 505 fossil assemblages sampled from Paleozoic strata of Laurentian North America. On the basis of associated sedimentary characteristics, each assemblage has been assigned to one of six environmental categories, ranging from onshore peritidal situations to offshore basinal conditions. For each taxonomic order and class, average numbers of genera in each category have been determined for each of 18 time units. These average alpha diversities have been contoured on time-environment diagrams and compared to patterns of global diversity.Three major generalizations are derived from these diagrams:1. Major groups tend to be environmentally conservative, maintaining their life zones of maximum and minimum alpha diversity over vast stretches of time.2. Onshore-offshore shifts are most common during early expansion or late contraction of groups, when their global diversity is rapidly waxing or (more slowly) waning.3. Maxima and minima in global diversity within the groups through time, with few exceptions, are reflected in alpha diversity as fluctuations within the environments of maximum richness and/or as variations in the range of environments occupied.The last observation indicates a tight link between local ecology and global diversity, although the direction of causation is not unambiguous: alpha diversity could be reflecting only the global pool from which species can be recruited into local communities. However, in view of the onshore-offshore shifts during early and late histories of clades we conclude that local ecology is the dominant factor in controlling global diversity, and provinciality is secondary.

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Spatial variability and human disturbance of sponge assemblages associated with mangrove roots in the southern Caribbean

Marine and Freshwater Research ◽

10.1071/mf10267 ◽

2011 ◽

Vol 62 (5) ◽

pp. 491 ◽

Cited By ~ 11

Author(s):

Edlin Guerra-Castro ◽

Paula Young ◽

Adriana Pérez-Vázquez ◽

Sophie Carteron ◽

Adriana Alvizu

Keyword(s):

Spatial Variability ◽

Human Disturbance ◽

Spatial Scales ◽

Caribbean Region ◽

Small Scale ◽

Ecological Processes ◽

Human Disturbances ◽

Β Diversity ◽

Southern Caribbean ◽

Mangrove Roots

Assemblages growing on Caribbean red-mangrove roots are very diverse and characteristically dominated by sponges. The scales of spatial variation of this fauna in the Caribbean region have not been hierarchically quantified, although such information is necessary to understand the relative importance of ecological processes and possible responses to anthropogenic disturbances. We used a hierarchical nested design to identify patterns of spatial variability at different scales, namely among roots, sites, localities and regions within the southern Caribbean. Simultaneously, the sampling considered the relative distance from sources of human disturbance to test the null hypothesis of no difference in sponge diversity among localities as a result of anthropogenic stress. Significant spatial variability in species composition was detected at all spatial scales, especially at the among-root scale. However, there were no differences associated with distance from human disturbance. These results indicate high regional and local β diversity, and also suggest that results from small-scale experiments cannot be scaled up to the entire community. Further, spatial analysis of sponge assemblages is not enough to detect deleterious effects of human disturbances on mangrove areas.

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Characterizing Peatland Microtopography Using Gradient and Microform-Based Approaches

Ecosystems ◽

10.1007/s10021-020-00481-z ◽

2020 ◽

Vol 23 (7) ◽

pp. 1464-1480 ◽

Cited By ~ 2

Author(s):

Jake D. Graham ◽

Nancy F. Glenn ◽

Lucas P. Spaete ◽

Paul J. Hanson

Keyword(s):

Spatial Variability ◽

Quantitative Methods ◽

Spatial Scales ◽

Methane Flux ◽

Small Scale ◽

Classification Methods ◽

Ecological Processes ◽

Elevation Gradients ◽

C Cycle ◽

Gradient Based

AbstractPeatlands represent an important component of the global carbon cycle, storing 180–621 Gt of carbon (C). Small-scale spatial variations in elevation, frequently referred to as microtopography, influence ecological processes associated with the peatland C cycle, including Sphagnum photosynthesis and methane flux. Microtopography can be characterized with measures of topographic variability and by using conceptual classes (microforms) linked to function: most commonly hummocks and hollows. However, the criteria used to define these conceptual classes are often poorly described, if at all, and vary between studies. Such inconsistencies compel development of explicit quantitative methods to classify microforms. Furthermore, gradient-based characterizations that describe spatial variability without the use of microforms are lacking in the literature. Therefore, the objectives of this study were to (1) calculate peatland microtopographical elevation gradients and measures of spatial variability, (2) develop three microform classification methods intended for specific purposes, and (3) evaluate and contrast classification methods. Our results suggest that at spatial scales much larger than microforms, elevation distributions are unimodal and are well approximated with parametric probability density functions. Results from classifications were variable between methods and years and exhibited significant differences in mean hollow areal coverages of a raised ombrotrophic bog. Our results suggest that the conceptualization and classification of microforms can significantly influence microtopographic structural metrics. The three explicit methods for microform classification described here may be used and built upon for future applications.

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The contribution of environmental and dispersal filters on phylogenetic and taxonomic beta diversity patterns in Amazonian tree communities

Oecologia ◽

10.1007/s00442-021-04981-0 ◽

2021 ◽

Author(s):

Juan Ernesto Guevara Andino ◽

Nigel C. A. Pitman ◽

Hans ter Steege ◽

Manuel Peralvo ◽

Carlos Cerón ◽

...

Keyword(s):

Beta Diversity ◽

Spatial Scales ◽

Dispersal Limitation ◽

Comprehensive Analysis ◽

Environmental Drivers ◽

Relative Importance ◽

Spatial Variables ◽

Ecuadorian Amazon ◽

Tree Communities

AbstractEnvironmental and dispersal filters are key determinants of species distributions of Amazonian tree communities. However, a comprehensive analysis of the role of environmental and dispersal filters is needed to understand the ecological and evolutionary processes that drive phylogenetic and taxonomic turnover of Amazonian tree communities. We compare measures of taxonomic and phylogenetic beta diversity in 41 one-hectare plots to test the relative importance of climate, soils, geology, geomorphology, pure spatial variables and the spatial variation of environmental drivers of phylogenetic and taxonomic turnover in Ecuadorian Amazon tree communities. We found low phylogenetic and high taxonomic turnover with respect to environmental and dispersal filters. In addition, our results suggest that climate is a significantly better predictor of phylogenetic turnover and taxonomic turnover than geomorphology and soils at all spatial scales. The influence of climate as a predictor of phylogenetic turnover was stronger at broader spatial scales (50 km2) whereas geomorphology and soils appear to be better predictors of taxonomic turnover at mid (5 km2) and fine spatial scales (0.5 km2) but a weak predictor of phylogenetic turnover at broad spatial scales. We also found that the combined effect of geomorphology and soils was significantly higher for taxonomic turnover at all spatial scales but not for phylogenetic turnover at large spatial scales. Geographic distances as proxy of dispersal limitation was a better predictor of phylogenetic turnover at distances of 50 < 500 km. Our findings suggest that climatic variation at regional scales can better predict phylogenetic and taxonomic turnover than geomorphology and soils.

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Community Assembly Mechanisms Underlying the Core and Random Bacterioplankton and Microeukaryotes in a River–Reservoir System

Water ◽

10.3390/w11061127 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1127 ◽

Cited By ~ 9

Author(s):

Alain Isabwe ◽

Kexin Ren ◽

Yongming Wang ◽

Feng Peng ◽

Huihuang Chen ◽

...

Keyword(s):

Community Assembly ◽

Anthropogenic Impacts ◽

Null Model ◽

Distribution Patterns ◽

Ecological Processes ◽

The Core ◽

Reservoir System ◽

Environmental Selection ◽

River Reservoir ◽

Plankton Communities

Whether bacterioplankton are assembled in the same way as microeukaryotes is a key question that has been answered only partially in microbial ecology. In particular, relating distribution patterns to the underlying ecological processes for plankton communities in highly dynamic ecosystems, such as river–reservoirs subjected to anthropogenic impacts, remains largely unstudied. Here, we analyzed taxonomic distribution patterns, and unraveled community assembly processes underlying the core and random bacterioplankton and microeukaryotes from a subtropical river–reservoir system. These plankton domains were modelled using the spatial abundance distributions (SpADs) of the operational taxonomic units (OTUs) as a proxy for abundant and rare taxa delineation. Both bacterioplankton and microeukaryote plankton communities exhibited significant distance–decay relationships, and samples were grouped depending on reservoir or river habitats. The neutral community model showed that 35–45% of the plankton community variation could be explained by neutral processes. The phylogenetic null model revealed that dispersal limitation accounted for the largest percentage of pairwise comparisons (42–68%), followed by environmental selection (18–25%). We concluded that similar prevalence of ecological processes acting on particular subsets of the bacterioplankton and microeukaryotes might have resulted from similar responses to environmental change, potentially induced by human activities in the watershed.

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Beta Diversity of Antarctic and Sub-Antarctic Benthic Communities Reveals a Major Role of Stochastic Assembly Processes

Frontiers in Marine Science ◽

10.3389/fmars.2021.780268 ◽

2021 ◽

Vol 8 ◽

Author(s):

Nelson Valdivia ◽

José Garcés-Vargas ◽

Ignacio Garrido ◽

Iván Gómez ◽

Pirjo Huovinen ◽

...

Keyword(s):

Stochastic Processes ◽

Spatial Variation ◽

Community Assembly ◽

Beta Diversity ◽

Seawater Temperature ◽

Environmental Filtering ◽

Ecological Processes ◽

Mean Values ◽

Sampling Protocols ◽

Strait Of Magellan

Community assembly is the result of both, deterministic and stochastic processes. The former encompasses niche-based local-scale mechanisms such as environmental filtering and biotic interactions; the latter includes ecological drift, probabilistic colonisation, and random extinctions. Using standardised sampling protocols, we show that the spatial variation in species composition (beta diversity) of shallow subtidal macrobenthic communities of sub-Antarctic (Strait of Magellan and Yendegaia Fjord [Beagle Channel]) and Antarctic (Fildes Bay [King George Island, West Antarctic Peninsula]) localities reflects a high contribution of stochastic processes to community assembly. Null model analyses indicated that random sampling from species pools of different sizes drove the observed among-locality differences in incidence- and abundance-based beta diversity. We analysed a normalised stochasticity ratio (NST), which delimits between more deterministic (<50%) and more stochastic (>50%) assembly. NST was notably larger than 50%, with mean values of 69.5% (95% CI = 69.2–69.8%), 62.5% (62.1–62.9%), and 72.8% (72.5–73.2%) in Strait of Magellan, Yendegaia Fjord, and Fildes Bay, respectively. Accordingly, environmental factors, such as depth, seawater temperature, salinity, and underwater light penetration, accounted for a small fraction of the spatial variation in community composition across the three localities. In this region, therefore, stochastic processes could have stronger effects on community assembly than deterministic niche-based factors. As anthropogenic biotic homogenisation continues apace, our study can give useful insights into the major ecological processes in Southern Ocean’ coastal marine communities.

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Disturbance alters beta-diversity but not the relative importance of community assembly mechanisms

Journal of Ecology ◽

10.1111/1365-2745.12436 ◽

2015 ◽

Vol 103 (5) ◽

pp. 1291-1299 ◽

Cited By ~ 66

Author(s):

Jonathan A. Myers ◽

Jonathan M. Chase ◽

Raelene M. Crandall ◽

Iván Jiménez

Keyword(s):

Community Assembly ◽

Beta Diversity ◽

Relative Importance

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Environmental selection and spatiotemporal structure of a major group of soil protists (Rhizaria: Cercozoa) in a temperate grassland

10.1101/531970 ◽

2019 ◽

Author(s):

Anna Maria Fiore-Donno ◽

Tim Richter-Heitmann ◽

Florine Degrune ◽

Kenneth Dumack ◽

Kathleen M. Regan ◽

...

Keyword(s):

Abiotic Factors ◽

Environmental Filtering ◽

Clay Content ◽

Time Lapse ◽

Major Group ◽

Small Scale ◽

Ecological Processes ◽

Environmental Selection ◽

Essential Components ◽

Soil Protists

AbstractSoil protists are increasingly appreciated as essential components of soil foodwebs; however, there is a dearth of information on the factors structuring their communities. Here we investigate the importance of different biotic and abiotic factors as key drivers of spatial and seasonal distribution of protistan communities. We conducted an intensive survey of a 10m2 grassland plot in Germany, focusing on a major group of protists, the Cercozoa. From 177 soil samples, collected from April to November, we obtained 694 Operational Taxonomy Units representing >6 million Illumina reads. All major cercozoan groups were present, dominated by the small flagellates of the Glissomonadida. We found evidence of environmental filtering structuring the cercozoan communities both spatially and seasonally. Spatial analyses indicated that communities were correlated within a range of four meters. Seasonal variations of bactevirores and bacteria, and that of omnivores after a time-lapse, suggested a dynamic prey-predator succession. The most influential edaphic properties were moisture and clay content, which differentially affected each functional group. Our study is based on an intense sampling of protists at a small scale, thus providing a detailed description of the niches occupied by different taxa/functional groups and the ecological processes involved.

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