scholarly journals Dispersal dynamics and local filtering vary with climate across a grassland landscape

2019 ◽  
Author(s):  
John Guittar ◽  
Deborah Goldberg ◽  
Kari Klanderud ◽  
Astrid Berge ◽  
Marta Ramírez Boixaderas ◽  
...  

ABSTRACTDispersal dynamics and local filtering interactively generate regional vegetation patterns, but empirical evidence of their combined influence in nature is scarce, representing a missing link between our theoretical understanding of community assembly and real-world observation. Here, we compare seed and adult plant communities at twelve grassland sites with different climates in southern Norway to explore the degree to which community membership is shaped by dispersal limitation and local niche-based filtering, and how this varies with climate. To do this, we first divide species at each site into two groups: “locally-transient” species, which occur as seeds but are rare or absent as adults (i.e., they arrive but are filtered out), or “locally-persistent” species, which occur consistently as adults in annual vegetation surveys. We then ask questions to reveal where, when, why, and how locally-transient species are systematically disfavored during community assembly. Our results led to four main conclusions: (1) the strength of local filtering on community membership increased with temperature, (2) surprisingly, local filtering was stronger during seedling emergence than during seedling establishment, (3) climate-based niche differences drove differential performance among species, especially for seeds dispersing outside of their realized climate niches into more stressful (colder and drier) climates, and (4) locally-transient species had traits that may made them better dispersers (smaller seeds) but poorer competitors for light (shorter statures, less persistent clonal connections) than locally-persistent species, providing a potential explanation for why they arrived to new sites but failed to establish persistent adult populations. Our study is one of the first to combine seed, seedling, and adult survey data across multiple sites with different climates to provide a rigorous empirical evaluation of the combined influence of dispersal limitation and local filtering on the generation and maintenance of climate-associated vegetation patterns.

2016 ◽  
Vol 13 (10) ◽  
pp. 2901-2911 ◽  
Author(s):  
Torsten Hauffe ◽  
Christian Albrecht ◽  
Thomas Wilke

Abstract. The Balkan Lake Ohrid is the oldest and most diverse freshwater lacustrine system in Europe. However, it remains unclear whether species community composition, as well as the diversification of its endemic taxa, is mainly driven by dispersal limitation, environmental filtering, or species interaction. This calls for a holistic perspective involving both evolutionary processes and ecological dynamics, as provided by the unifying framework of the “metacommunity speciation model”.The current study used the species-rich model taxon Gastropoda to assess how extant communities in Lake Ohrid are structured by performing process-based metacommunity analyses. Specifically, the study aimed (1) to identifying the relative importance of the three community assembly processes and (2) to test whether the importance of these individual processes changes gradually with lake depth or discontinuously with eco-zone shifts.Based on automated eco-zone detection and process-specific simulation steps, we demonstrated that dispersal limitation had the strongest influence on gastropod community composition. However, it was not the exclusive assembly process, but acted together with the other two processes – environmental filtering and species interaction. The relative importance of the community assembly processes varied both with lake depth and eco-zones, though the processes were better predicted by the latter.This suggests that environmental characteristics have a pronounced effect on shaping gastropod communities via assembly processes. Moreover, the study corroborated the high importance of dispersal limitation for both maintaining species richness in Lake Ohrid (through its impact on community composition) and generating endemic biodiversity (via its influence on diversification processes). However, according to the metacommunity speciation model, the inferred importance of environmental filtering and biotic interaction also suggests a small but significant influence of ecological speciation. These findings contribute to the main goal of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) deep drilling initiative – inferring the drivers of biotic evolution – and might provide an integrative perspective on biological and limnological dynamics in ancient Lake Ohrid.


2022 ◽  
Author(s):  
Raven L Bier ◽  
Máté Vass ◽  
Anna J Székely ◽  
Silke Langenheder

Understanding processes that determine community membership and abundance is important for many fields from theoretical community ecology to conservation. However, spatial community studies are often conducted only at a single timepoint despite the known influence of temporal variability on community assembly processes. Here we used a spatiotemporal study to determine how environmental fluctuation differences induced by mesocosm volumes (larger volumes were more stable) influence assembly processes of aquatic bacterial metacommunities along a press disturbance gradient. By combining path analysis and network approaches, we found mesocosm size categories had distinct relative influences of assembly process and environmental factors that determined spatiotemporal bacterial community composition, including dispersal and species sorting by conductivity. These processes depended on, but were not affected proportionately by, mesocosm size. Low fluctuation, large mesocosms primarily developed through the interplay of species sorting that became more important over time and transient priority effects as evidenced by more time-delayed associations. High fluctuation, small mesocosms had regular disruptions to species sorting and greater importance of ecological drift and dispersal limitation indicated by lower richness and higher taxa replacement. Together, these results emphasize that environmental fluctuations influence ecosystems over time and its impacts are modified by biotic properties intrinsic to ecosystem size.


2021 ◽  
Vol 8 ◽  
Author(s):  
Jiandong Zhang ◽  
Anyi Hu ◽  
Yingting Sun ◽  
Qingsong Yang ◽  
Junde Dong ◽  
...  

The coral microbiome is one of the most complex microbial biospheres. However, the ecological processes shaping coral microbiome community assembly are not well understood. Here, we investigated the abundance, diversity, and community assembly mechanisms of coral-associated microbes from a highly diverse coral metacommunity in the South China Sea. Compared to seawater, the coral microbial metacommunity were defined by highly variable bacterial abundances among individual coral samples, high species evenness but not high species richness, high β-diversity, and a small core microbiome. We used variation partitioning analysis, neutral community model, and null model to disentangle the influences of different ecological processes in coral microbiome assembly. Measured physico-chemical parameters of the surrounding seawater and the spatial factor together explained very little of the variation in coral microbiome composition. Neutral processes only explained a minor component of the variation of coral microbial communities, suggesting a non-stochastic community assembly. Homogeneous and heterogeneous selection, but not dispersal, contributed greatly to the assembly of the coral microbiome. Such selection could be attributed to the within-host environments rather than the local environments. Our results demonstrated that dispersal limitation and host filtering contribute significantly to the assembly of discrete coral microbial regimes and expand the metacommunity diversity.


Author(s):  
Mohammad Bahram ◽  
Kati Kings ◽  
Mari Pent ◽  
Sergei Polme ◽  
Daniyal Gohar ◽  
...  

Bacterial and fungal endophytes form diverse communities and contribute to the performance and health of their host plants. Recent evidence suggests that both host related factors and environmental conditions determine the community structure of plant endophytes. Yet, we know little about their distribution patterns, and underlying community assembly mechanisms across plant compartments. Here we analysed the structure of bacterial and fungal communities associated with tree compartments as well as their underlying soils across 12 tree individuals in boreal forests. We found that the structure of bacterial and fungal communities depends more strongly on the vertical location of tree compartments rather than the locality, species, and individuals of host trees. Microbial communities showed much stronger host specificity in aboveground than belowground compartments. While having lower compartment community variability compared to fungi, bacterial communities were markedly more distinct between below- and aboveground components but not between hosts, reflecting the greater importance of environmental filtering rather than dispersal limitation and host identity in their community assembly. Our data suggest that spatial distance from soil as a major microbiome source contributes to the formation of microbiomes in plants, and that bacterial and fungal communities may follow contrasting assembly processes.


Ecosphere ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. e01650 ◽  
Author(s):  
Markus A. K. Sydenham ◽  
Stein R. Moe ◽  
Michael Kuhlmann ◽  
Simon G. Potts ◽  
Stuart P. M. Roberts ◽  
...  

2019 ◽  
Author(s):  
Francesco Ricci ◽  
Vanessa Rossetto Marcelino ◽  
Linda Blackall ◽  
Michael Kühl ◽  
Monica Medina ◽  
...  

Coral microbial ecology is a burgeoning field, driven by the urgency of understanding coral health and slowing reef loss due to climate change. Coral resilience depends on its microbiota, and both the tissue and the underlying skeleton are home to a rich biodiversity of eukaryotic, bacterial and archaeal species that form an integral part of the coral holobiont. New techniques now enable detailed studies of the endolithic habitat, and our knowledge of the skeletal microbial community and its eco-physiology is increasing rapidly, with multiple lines of evidence for the importance of the skeletal microbiota in coral health and functioning. Here, we review the roles these organisms play in the holobiont, including nutritional exchanges with the coral host and decalcification of the host skeleton. Microbial metabolism causes steep physico-chemical gradients in the skeleton, creating micro-niches that, along with dispersal limitation and priority affects, define the fine-scale microbial community assembly. Coral bleaching causes drastic changes in the skeletal microbiome, which can mitigate bleaching effects and promote coral survival during stress periods, but may also have detrimental effects. Finally, we discuss the idea that the skeleton may function as a microbial reservoir that can promote recolonization of the tissue microbiome following dysbiosis and help the coral holobiont return to homeostasis.


2021 ◽  
Author(s):  
Aditi Sengupta ◽  
Sarah J. Fansler ◽  
Rosalie K. Chu ◽  
Robert E. Danczak ◽  
Vanessa A. Garayburu-Caruso ◽  
...  

Abstract. Conceptual frameworks linking microbial community membership, properties, and processes with the environment and emergent function have been proposed but remain untested. Here we refine and test a recent conceptual framework using hyporheic zone sediments exposed to wetting/drying transitions. Throughout the system we found threshold-like responses to the duration of desiccation. Membership of the putatively active community – but not the whole community – responded due to enhanced deterministic selection (an emergent community property). Concurrently, the thermodynamic properties of organic matter became less favorable for oxidation (an environmental component) and respiration decreased (a microbial process). While these responses were step functions of desiccation, we observed continuous monotonic relationships among community assembly, respiration, and organic matter thermodynamics. Placing the results in context of our conceptual framework points to previously unrecognized internal feedbacks that are initiated by disturbance, mediated by thermodynamics, and that cause the impacts of disturbance to be dependent on the history of disturbance.


2019 ◽  
Vol 12 ◽  
pp. 194008291989385
Author(s):  
Hui Zhang ◽  
Wanhui Ye ◽  
Juyu Lian

Functional redundancy is an important tool for justifying and prioritizing species protection in forest ecosystem, but it is a scale-dependent. If functional redundancy really exists, functional trait composition tends to have higher predictive ability of community assembly than species composition. Thus, comparing the differences in the predictive ability of community assembly between species and functional trait compositions across spatial scale represents a useful tool to quantify how functional redundancy varies across spatial scales. Here, we used variation partitioning in combination with distance-based Moran’s eigenvector maps to compare the differences in the predictive ability of community assembly between species composition and functional trait composition across spatial scales (20, 30, 40, 50, and 100 m) in a 20-ha subtropical forest plot. We found that functional trait composition possessed higher predictive ability of niche-based abiotic filtering process than species composition within 40 m. At 50 and 100 m scales, both species and functional trait compositions had approximately equal predictive ability of dispersal limitation processes. Thus, functional redundancy can only exist within 40 m scale but not 50 and 100 m scales. As a result, priority species loss protection should be performed at 50 and 100 m scales.


mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Pengfa Li ◽  
Weitao Li ◽  
Alex J. Dumbrell ◽  
Ming Liu ◽  
Guilong Li ◽  
...  

ABSTRACT Fungi underpin almost all terrestrial ecosystem functions, yet our understanding of their community ecology lags far behind that of other organisms. Here, red paddy soils in subtropical China were collected across a soil depth profile, comprising 0-to-10-cm- (0-10cm-), 10-20cm-, and 20-40cm-deep layers. Using Illumina MiSeq amplicon sequencing of the internal transcribed spacer (ITS) region, distance-decay relationships (DDRs), and ecological models, fungal assemblages and their spatial patterns were investigated from each soil depth. We observed significant spatial variation in fungal communities and found that environmental heterogeneity decreased with soil depth, while spatial variation in fungal communities showed the opposite trend. DDRs occurred only in 0-10cm- and 10-20cm-deep soil layers, not in the 20-40cm layer. Our analyses revealed that the fungal community assembly in the 0-10cm layer was primarily governed by environmental filtering and a high dispersal rate, while in the deeper layer (20-40cm), it was primarily governed by dispersal limitation with minimal environmental filtering. Both environmental filtering and dispersal limitation controlled fungal community assembly in the 10-20cm layer, with dispersal limitation playing the major role. Results demonstrate the decreasing importance of environmental filtering and an increase in the importance of dispersal limitation in structuring fungal communities from shallower to deeper soils. Effectively, “everything is everywhere, but the environment selects,” although only in shallower soils that are easily accessible to dispersive fungal propagules. This work highlights that perceived drivers of fungal community assembly are dependent on sampling depth, suggesting that caution is required when interpreting diversity patterns from samples that integrate across depths. IMPORTANCE In this work, Illumina MiSeq amplicon sequencing of the ITS region was used to investigate the spatial variation and assembly mechanisms of fungal communities from different soil layers across paddy fields in subtropical China, and the results demonstrate the decreasing importance of environmental filtering and an increase in the importance of dispersal limitation in structuring fungal communities from shallower to deeper soils. Therefore, the results of this study highlight that perceived drivers of fungal community assembly are dependent on sampling depth and suggest that caution is required when interpreting diversity patterns from samples that integrate across depths. This is the first study focusing on assemblages of fungal communities in different soil layers on a relatively large scale, and we thus believe that this study is of great importance to researchers and readers in microbial ecology, especially in microbial biogeography, because the results can provide sampling guidance in future studies of microbial biogeography.


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