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- Angeler, David, et al.
(författare)
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A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels
- 2015
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 5, s. 1235-1248
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Tidskriftsartikel (refereegranskat)abstract
- The hypotheses that beta diversity should increase with decreasing latitude and increase with spatial extent of a region have rarely been tested based on a comparative analysis of multiple datasets, and no such study has focused on stream insects. We first assessed how well variability in beta diversity of stream insect metacommunities is predicted by insect group, latitude, spatial extent, altitudinal range, and dataset properties across multiple drainage basins throughout the world. Second, we assessed the relative roles of environmental and spatial factors in driving variation in assemblage composition within each drainage basin. Our analyses were based on a dataset of 95 stream insect metacommunities from 31 drainage basins distributed around the world. We used dissimilarity-based indices to quantify beta diversity for each metacommunity and, subsequently, regressed beta diversity on insect group, latitude, spatial extent, altitudinal range, and dataset properties (e.g., number of sites and percentage of presences). Within each metacommunity, we used a combination of spatial eigenfunction analyses and partial redundancy analysis to partition variation in assemblage structure into environmental, shared, spatial, and unexplained fractions. We found that dataset properties were more important predictors of beta diversity than ecological and geographical factors across multiple drainage basins. In the within-basin analyses, environmental and spatial variables were generally poor predictors of variation in assemblage composition. Our results revealed deviation from general biodiversity patterns because beta diversity did not show the expected decreasing trend with latitude. Our results also call for reconsideration of just how predictable stream assemblages are along ecological gradients, with implications for environmental assessment and conservation decisions. Our findings may also be applicable to other dynamic systems where predictability is low.
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| 2. |
- Göthe, Emma, et al.
(författare)
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Impacts of habitat degradation and stream spatial location on biodiversity in a disturbed riverine landscape
- 2015
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Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 24, s. 1423-1441
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Tidskriftsartikel (refereegranskat)abstract
- The ongoing degradation of freshwater habitat quality and subsequent losses of biodiversity is alarming. One key to successful freshwater management is to understand how different scale-dependent diversity components (i.e. gamma-, alpha- and beta-diversity) change along present-day anthropogenic impact gradients. We used macrophyte, fish and macroinvertebrate data from Danish lowland streams to investigate whether (1) high connectivity in reaches situated in lower parts of the stream network (downstream sites) generates high alpha-diversity, while dispersal limitation and high habitat heterogeneity across the more isolated upper reaches (headwater sites) generate high beta-diversity, (2) gamma-, alpha- and beta- diversity decrease with increasing hydromorphological impact and (3) high connectivity in downstream reaches buffers against impacts on biodiversity. Results showed that alpha-diversity was higher in downstream sites, while headwaters did not exhibit greater beta-diversity. We observed a significant but relatively small decline in alpha-diversity with increasing hydromorphological impact, while beta-diversity changed more unpredictably along the gradient. There was no clear mitigating effect in downstream reaches as the reduction in diversity from low to high impacted sites was similar between upper and lower reaches. We suggest that the results, which generally contradicted our predictions, partly reflect the intense historic and present land use in the region leading to an isolation of available source communities and a diminished regional species pool. The importance of having a landscape perspective in conservation management in highly impacted regions is emphasised because it is a prerequisite for recolonisation and population stability over time.
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