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- Brose, Ulrich, et al.
(författare)
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Predicting the consequences of species lossusing size-structured biodiversity approaches
- 2017
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Ingår i: Biological Reviews. - : Wiley-Blackwell. - 1464-7931 .- 1469-185X. ; 92:2, s. 684-697
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Forskningsöversikt (refereegranskat)abstract
- Understanding the consequences of species loss in complex ecological communities is one of the great challenges in current biodiversity research. For a long time, this topic has been addressed by traditional biodiversity experiments. Most of these approaches treat species as trait-free, taxonomic units characterizing communities only by species number without accounting for species traits. However, extinctions do not occur at random as there is a clear correlation between extinction risk and species traits. In this review, we assume that large species will be most threatened by extinction and use novel allometric and size-spectrum concepts that include body mass as a primary species trait at the levels of populations and individuals, respectively, to re-assess three classic debates on the relationships between biodiversity and (i) food-web structural complexity, (ii) community dynamic stability, and (iii) ecosystem functioning. Contrasting current expectations, size-structured approaches suggest that the loss of large species, that typically exploit most resource species, may lead to future food webs that are less interwoven and more structured by chains of interactions and compartments. The disruption of natural body-mass distributions maintaining food-web stability may trigger avalanches of secondary extinctions and strong trophic cascades with expected knock-on effects on the functionality of the ecosystems. Therefore, we argue that it is crucial to take into account body size as a species trait when analysing the consequences of biodiversity loss for natural ecosystems. Applying size-structured approaches provides an integrative ecological concept that enables a better understanding of each species' unique role across communities and the causes and consequences of biodiversity loss.
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| 2. |
- O'Gorman, Eoin J., et al.
(författare)
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Interaction strength, food web topology and the relative importance of species in food webs.
- 2010
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Ingår i: Journal of Animal Ecology. - : Wiley-Blackwell Publishing Ltd.. - 0021-8790 .- 1365-2656. ; 79:3, s. 682-692
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Tidskriftsartikel (refereegranskat)abstract
- 1. We established complex marine communities, consisting of over 100 species, in large subtidal experimental mesocosms. We measured the strength of direct interactions and the net strength of direct and indirect interactions between the species in those communities, using a combination of theoretical and empirical approaches.2. Theoretical predictions of interaction strength were derived from the interaction coefficient matrix, which was parameterised using allometric predator–prey relationships. Empirical estimates of interaction strength were quantified using the ln-ratio, which measures the change in biomass density of species A in the presence and absence of species B.3. We observed that highly connected species tend to have weak direct effects and net effects in our experimental food webs, whether we calculate interaction strength theoretically or empirically.4. We found a significant correlation between our theoretical predictions and empirical estimates of direct effects and net effects. The net effects correlation was much stronger, indicating that our experimental communities were dominated by a mixture of direct and indirect effects.5. Re-calculation of the theoretical predictions of net effects after randomising predator and prey body masses did not affect the negative relationship with connectance.6. These results suggest that food web topology, which in this system is constrained by body mass, is overwhelmingly important for the magnitude of direct and indirect interactions and hence species importance in the face of biodiversity declines.
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