Flow directionality, mountain barriers and functional traits determine diatom metacommunity structuring of high mountain streams

Dong, Xiaoyu; Li, Bin; He, Fengzhi; Gu, Yang; Sun, Meiqin; Zhang, Haomiao; Tan, Lu; Xiao, Wen; Liu, Shuoran; Cai, Qinghua

doi:10.1038/srep24711

Cited by 78 publications

(94 citation statements)

References 57 publications

(101 reference statements)

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“…This suggests that the regional effects might also be partially manifested via local variables. This pattern has also been observed in high‐mountain aquatic communities, including diatoms (Dong et al., ) and invertebrates (Tonkin et al., ). On the other hand, stream diatom communities of Sorata and Sehuencas formed a clear group together with lake diatom communities of the Bolivian Amazon lowlands.…”

Section: Discussionsupporting

confidence: 56%

Geo‐climatic factors drive diatom community distribution in tropical South American freshwaters

et al. 2018

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Patterns that maintain and generate biodiversity of macro‐organisms in the Neotropics are widely discussed in the scientific literature, yet the spatial ecology of micro‐organisms is largely unknown. The unique character of the tropical Andes and adjacent Amazon lowlands generates a wide gradient of environmental conditions to advance our understanding of what drives community assembly and diversity processes. We analysed the distribution patterns of benthic diatoms (unicellular siliceous algae) as a model group of microbial passive dispersers, including predictors that describe limnological and geo‐climatic gradients for a total of 113 waterbodies (0–28°S and 58–80°W), including lakes and streams. Complementary multivariate statistical analyses were performed to correlate (1) community composition and (2) diatom species richness with environmental and spatial factors to infer niche‐based and dispersal‐based assembly processes, respectively. Results showed that two gradients structured both diatom assemblages and waterbodies, namely climate and landscape configuration. Variance partitioning revealed that broadscale spatial variables (distance‐based Moran's Eigenvectors) outperformed the two environmental components (limnological and geo‐climatic), suggesting dispersal‐assembled communities. However, diatom assemblages were structured by geo‐climatic (regional) factors in certain lakes in the northern and central Andes, although their effects were partially manifested via local variables after the geographical distances were factored out. In a similar way, climatic and topographic structuring homogenized lake and stream communities within ecoregions, as indicated by the strong overlap between the two community types and the weak correlation between biota and limnological variables. Notably, a significant increase in diatom species richness was related to increased water connectivity, interpreted to indicate that a decrease in the remoteness of the system increase species number. Synthesis. We emphasize the strength of macroecological gradients (landscape configuration and climatic factors) in affecting both diatom diversity and community composition in the South American tropics. In this context, our results and the commonalities of ecoregion patterning with groups of macro‐organisms (vegetation) suggest the need to integrate microbial ecology into a macroecology framework to unravel mechanisms behind diversity gradients.

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Section: Discussionsupporting

confidence: 56%

Geo‐climatic factors drive diatom community distribution in tropical South American freshwaters

et al. 2018

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“…Consistent with previous studies on planktonic organisms (Declerck et al., ; Dong et al., ), the spatial configuration of peatlands and pools had significant effects on cladoceran community structure at higher spatial scales (intervalleys and within valleys), in terms of both the abundance and presence/absence of species. This result suggests that larger distances and dispersal barriers may limit the probability of individuals arriving at distant pools.…”

Section: Discussionsupporting

confidence: 89%

“…The relative importance of these filters depended on spatial scale. Variations of community composition among valleys (intervalleys) were explained to similar extents by the environmental and spatial filters, suggesting that dispersal limitation and niche processes due to topographical barriers, and high environmental heterogeneity at larger spatial scales might interact together determining the structure of zooplankton community variation, consistent with findings for other mountain ecosystems (Declerck et al., ; Dong et al., ). Both filters were important to explain within‐valley differences, but the spatial filter had a stronger effect than the environmental filter, suggesting that limitations on the dispersal of zooplanktonic species, due to large geographic and elevational distances, played a more important role in this context.…”

Section: Discussionsupporting

confidence: 82%

Environmental and spatial filters of zooplankton metacommunities in shallow pools in high‐elevation peatlands in the tropical Andes

et al. 2018

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Understanding metacommunity organisation in freshwater ecosystems is particularly important at high elevation in the tropical Andes, as this region is considered an important biodiversity hotspot with many endemic species threatened by climate change. High levels of dispersal at the regional scale and strong environmental filters at the local scale are thought to structure aquatic communities in these systems. However, metacommunity organisation patterns at the limit of aquatic life (>4,500 m a.s.l.) remain largely unknown. Given the extreme environmental conditions experienced by organisms at high elevation, environment filters would be expected to play a greater role than spatial filters in community assemblages. We assessed the effects of environmental and spatial filters on zooplankton (Cladocera), to gain insight into metacommunity organisation in the shallow high‐elevation pools of the tropical Andes. We sampled zooplankton communities and assessed nine environmental variables, for 200 pools from 20 peatlands in the Cordillera Real of Bolivia. We performed redundancy and variation partitioning analyses on both abundance and presence/absence data, to evaluate the contribution of environmental and spatial processes (geographic and elevation distances) to cladoceran metacommunity assembly at different spatial scales. We identified 18 cladoceran species, eight of which were endemic to the Andes. We found that both environment and spatial filters made a significant contribution to the structuring of cladoceran communities at higher spatial scales (i.e. intervalleys and within valleys), whereas only the environmental filter operated at small spatial scales (i.e. within peatlands). Elevation had a significant effect on cladoceran community variation (e.g. 6.9% within valleys, for abundance data), but not on species diversity. Similar patterns were obtained with presence/absence data. Macrophyte cover, pool area and pH were the most important variables explaining community variation and the species diversity of cladocerans at pool level. These results suggest that species sorting is probably the main process generating variation in cladoceran communities at all spatial scales. At larger spatial scales (intervalleys and within valleys), limited dispersal may also filter species composition. We identified factors significantly contributing to the variation observed, but their overall explanatory power was low. This finding highlights the difficulties involved in evaluating the response of aquatic organisms to their environment and suggests that other environmental variables should be considered. Moreover, frequent and unpredictable disturbances and high stochasticity probably operate simultaneously with environmental filters to structure zooplankton organisation in these unique and harsh aquatic systems.

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“…Environmental heterogeneity is pronounced in mountain regions, as climatic shifts along elevational gradients amplify spatial variations in temperature, precipitation, solar radiation, and regional land cover characteristics. The distinctive topographic complexities of mountain regions may also impede biological connectivity, with the potential implication of reducing propagule pressure and the ability for species to reach and colonize novel habitats (Dong et al 2016). The distinctive topographic complexities of mountain regions may also impede biological connectivity, with the potential implication of reducing propagule pressure and the ability for species to reach and colonize novel habitats (Dong et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Macroecological drivers of zooplankton communities across the mountains of western North America

et al. 2018

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Disentangling the environmental and spatial drivers of biological communities across large scales increasingly challenges modern ecology in a rapidly changing world. Here, we investigate the hierarchical and trait-based organization of regional and local factors of zooplankton communities at a macroscale of 1240 mountain lakes and ponds spanning western North America (California, USA, to Yukon Territory, Canada). Variation partitioning was used to test the hypothesized importance of climate, connectivity, catchment features, and exotic sportfish to zooplankton betadiversity in the context of key functional traits (body size and reproductive dispersal potential) given the pronounced environmental heterogeneity (e.g. thermal gradients), topographic barriers, and legacy of stocked fish in mountainous regions. Dispersal limitation was inferred from multispecies patch connectivity estimates based on nearest and average distances to occupied patches. Environmental heterogeneity best explained community composition as catchment/lake features (morphometry, land cover, and lithology) collectively captured greater variation than did climate (temperature, precipitation, and solar radiation), local stocking, or connectivity; however, single climatic variables captured the most variation individually. Macrospatial variation by larger obligate sexual species was better explained than that by smaller cyclically parthenogenetic asexual species. Our results provide several novel insights into the macroecology of zooplankton of the North American Cordillera, demonstrating their stronger associations to climatically driven aquatic-terrestrial habitat coupling than dynamics arising from introduced salmonids, human land-use, or species dispersal. These findings highlight the clear and important role of these communities as bioindicators of the limnological impacts of accelerating rates of climate change, as their responses appear relatively not confounded by local human perturbations or dispersal limitation.

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Flow directionality, mountain barriers and functional traits determine diatom metacommunity structuring of high mountain streams

Cited by 78 publications

References 57 publications

Geo‐climatic factors drive diatom community distribution in tropical South American freshwaters

Geo‐climatic factors drive diatom community distribution in tropical South American freshwaters

Environmental and spatial filters of zooplankton metacommunities in shallow pools in high‐elevation peatlands in the tropical Andes

Macroecological drivers of zooplankton communities across the mountains of western North America

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