| 1. |
- Graco-Roza, Caio, et al.
(författare)
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Distance decay 2.0 – A global synthesis of taxonomic and functional turnover in ecological communities
- 2022
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 31:7, s. 1399-1421
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Understanding the variation in community composition and species abundances (i.e., beta-diversity) is at the heart of community ecology. A common approach to examine beta-diversity is to evaluate directional variation in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distance. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 148 datasets comprising different types of organisms and environments.Location: Global.Time period: 1990 to present.Major taxa studied: From diatoms to mammals.Method: We measured the strength of the decay using ranked Mantel tests (Mantel r) and the rate of distance decay as the slope of an exponential fit using generalized linear models. We used null models to test whether functional similarity decays faster or slower than expected given the taxonomic decay along the spatial and environmental distance. We also unveiled the factors driving the rate of decay across the datasets, including latitude, spatial extent, realm and organismal features.Results: Taxonomic distance decay was stronger than functional distance decay along both spatial and environmental distance. Functional distance decay was random given the taxonomic distance decay. The rate of taxonomic and functional spatial distance decay was fastest in the datasets from mid-latitudes. Overall, datasets covering larger spatial extents showed a lower rate of decay along spatial distance but a higher rate of decay along environmental distance. Marine ecosystems had the slowest rate of decay along environmental distances.Main conclusions: In general, taxonomic distance decay is a useful tool for biogeographical research because it reflects dispersal-related factors in addition to species responses to climatic and environmental variables. Moreover, functional distance decay might be a cost-effective option for investigating community changes in heterogeneous environments.
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| 2. |
- Virta, Leena, et al.
(författare)
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Biodiversity Loss Threatens the Current Functional Similarity of Beta Diversity in Benthic Diatom Communities
- 2021
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 81, s. 293-303
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Tidskriftsartikel (refereegranskat)abstract
- The global biodiversity loss has increased the need to understand the effects of decreasing diversity, but our knowledge on how species loss will affect the functioning of communities and ecosystems is still very limited. Here, the levels of taxonomic and functional beta diversity and the effect of species loss on functional beta diversity were investigated in an estuary that provides a naturally steep environmental gradient. The study was conducted using diatoms that are among the most important microorganisms in all aquatic ecosystems and globally account for 40% of marine primary production. Along the estuary, the taxonomic beta diversity of diatom communities was high (Bray-Curtis taxonomic similarity 0.044) and strongly controlled by the environment, particularly wind exposure, salinity, and temperature. In contrast, the functional beta diversity was low (Bray-Curtis functional similarity 0.658) and much less controlled by the environment. Thus, the diatom communities stayed functionally almost similar despite large changes in species composition and environment. This may indicate that, through high taxonomic diversity and redundancy in functions, microorganisms provide an insurance effect against environmental change. However, when studying the effect of decreasing species richness on functional similarity of communities, simulated species loss to 45% of the current species richness decreased functional similarity significantly. This suggests that decreasing species richness may increase variability and reduce the stability and resilience of communities. These results highlight the importance of high taxonomic biodiversity for the stable functioning of benthic communities.
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| 3. |
- Virta, Leena, et al.
(författare)
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Diversity and distribution across a large environmental and spatial gradient : Evaluating the taxonomic and functional turnover, transitions and environmental drivers of benthic diatom communities
- 2020
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 29:12, s. 2214-2228
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Global biodiversity loss has raised interest in understanding variation in diversity at different scales. In particular, studies conducted across large spatial gradients are crucial, because they can increase perspectives on how ecological patterns change relative to environmental factors and facilitate predictions of possible responses to environmental change. We explored the full extent of a brackish sea to test the hypotheses that: (a) benthic communities are defined by the limited ranges of species, controlled by varying drivers along a large environmental gradient; (b) the responses of taxonomic and functional community composition and turnover to the environmental gradient are different, thus highlighting the need to include both measures in ecological studies; and (c) diversity reaches the minimum at intermediate salinities (Remane curve) owing to the low adaptation of freshwater and marine species.Location: A large environmental and spatial gradient spanning the entire Swedish coastline (c. 2,300 km; salinity 1.2-27.6), the Baltic Sea.Time period: August 2018.Major taxa studied: Benthic diatoms.Methods: We assessed environmental drivers for the communities and calculated the taxonomic and functional alpha and beta diversity along the gradient. We also compared the taxonomic and functional composition and diversity of communities among areas with different salinity.Results: We found support for the hypothesis of limited species ranges, because taxonomic beta diversity, mainly induced by changes in salinity and climate, was high, whereas functional beta diversity remained considerably lower, and the composition and diversity of communities, in addition to environmental drivers controlling the communities, differed between regions with different salinity. The lowest taxonomic diversity was found at intermediate salinities of 5-6.Main conclusions: These findings advance understanding of large-scale patterns of benthic diversity, emphasize the importance of large gradient studies for a better understanding of general ecological patterns and highlight the vulnerability of brackish water ecosystems as ecologically important tipping-point realms.
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| 4. |
- Virta, Leena, et al.
(författare)
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Stable Seasonal and Annual Alpha Diversity of Benthic Diatom Communities Despite Changing Community Composition
- 2020
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The global biodiversity loss has raised interest in the different facets of diversity, and the importance of diversity for ecosystem functions has been recognized. However, our knowledge on seasonal and inter-annual variation in the composition and diversity of communities is still poor. Here, we investigated the seasonal and inter-annual changes in taxonomic and functional community composition and diversity of benthic diatoms in a coastal habitat of the northern Baltic Sea, where seasonal and inter-annual variation of climate is pronounced. We found that the taxonomic and functional alpha diversity remained stable at seasonal and inter-annual level despite strong changes in community composition. However, alpha diversity decreased during an exceptionally warm winter possibly due to disturbances induced by the lack of ice. This may suggest that climate warming and consequently limited ice cover will affect the diversity of benthic communities.
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| 5. |
- Virta, Leena, et al.
(författare)
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The diversity of benthic diatoms affects ecosystem productivity in heterogeneous coastal environments
- 2019
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 100:9
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Tidskriftsartikel (refereegranskat)abstract
- The current decrease in biodiversity affects all ecosystems, and the impacts of diversity on ecosystem functioning need to be resolved. So far, marine studies about diversity-ecosystem productivity-relationships have concentrated on small-scale, controlled experiments, with often limited relevance to natural ecosystems. Here, we provide a real-world study on the effects of microorganismal diversity (measured as the diversity of benthic diatom communities) on ecosystem productivity (using chlorophyll a concentration as a surrogate) in a heterogeneous marine coastal archipelago. We collected 78 sediment cores at 17 sites in the northern Baltic Sea and found exceptionally high diatom diversity (328 observed species). We used structural equation models and quantile regression to explore relationships between diatom diversity and productivity. Previous studies have found contradictory results in the relationship between microorganismal diversity and ecosystem productivity, but we showed a linear and positive basal relationship between diatom diversity and productivity, which indicates that diatom diversity most likely forms the lowest boundary for productivity. Thus, although productivity can be high even when diatom diversity is low, high diatom diversity supports high productivity. The trait composition was more effective than taxonomical composition in showing such a relationship, which could be due to niche complementarity. Our results also indicated that environmental heterogeneity leads to substantial patchiness in the diversity of benthic diatom communities, mainly induced by the variation in sediment organic matter content. Therefore, future changes in precipitation and river runoff and associated changes in the quality and quantity of organic matter in the sea, will also affect diatom communities and, hence, ecosystem productivity. Our study suggests that benthic microorganisms are vital for ecosystem productivity, and together with the substantial heterogeneity of coastal ecosystems, they should be considered when evaluating the potential productivity of coastal areas.
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