| 1. |
- Brännström, Åke, 1975-, et al.
(författare)
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Rigorous conditions for food-web intervality in high-dimensional trophic niche spaces
- 2011
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Ingår i: Journal of Mathematical Biology. - : Springerlink. - 0303-6812 .- 1432-1416. ; 63:3, s. 575-592
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Tidskriftsartikel (refereegranskat)abstract
- Food webs represent trophic (feeding) interactions in ecosystems. Since the late 1970s, it has been recognized that food-webs have a surprisingly close relationship to interval graphs. One interpretation of food-web intervality is that trophic niche space is low-dimensional, meaning that the trophic character of a species can be expressed by a single or at most a few quantitative traits. In a companion paper we demonstrated, by simulating a minimal food-web model, that food webs are also expected to be interval when niche-space is high-dimensional. Here we characterize the fundamental mechanisms underlying this phenomenon by proving a set of rigorous conditions for food-web intervality in high-dimensional niche spaces. Our results apply to a large class of food-web models, including the special case previously studied numerically.
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| 2. |
- Rossberg, Axel G, et al.
(författare)
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Food-web structure in low- and high-dimensional trophic niche spaces
- 2010
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Ingår i: Journal of the Royal Society Interface. - : Royal Society Publishing. - 1742-5689 .- 1742-5662. ; 7:53, s. 1735-1743
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Tidskriftsartikel (refereegranskat)abstract
- A question central to modelling and, ultimately, managing food webs concerns the dimensionality of trophic niche space, that is, the number of independent traits relevant for determining consumer-resource links. Food-web topologies can often be interpreted by assuming resource traits to be specified by points along a line and each consumer's diet to be given by resources contained in an interval on this line. This phenomenon, called intervality, has been known for 30 years and is widely acknowledged to indicate that trophic niche space is close to one-dimensional. We show that the degrees of intervality observed in nature can be reproduced in arbitrary-dimensional trophic niche spaces, provided that the processes of evolutionary diversification and adaptation are taken into account. Contrary to expectations, intervality is least pronounced at intermediate dimensions and steadily improves towards lower- and higher-dimensional trophic niche spaces.
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| 3. |
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| 4. |
- Rossberg, Axel G., et al.
(författare)
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Lets Train More Theoretical Ecologists - Here Is Why
- 2019
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Ingår i: Trends in Ecology & Evolution. - : ELSEVIER SCIENCE LONDON. - 0169-5347 .- 1872-8383. ; 34:9, s. 759-762
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A tangled web of vicious circles, driven by cultural issues, has prevented ecology from growing strong theoretical roots. Now this hinders development of effective conservation policies. To overcome these barriers in view of urgent societal needs, we propose a global network of postgraduate theoretical training programs.
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| 5. |
- Rossberg, Axel, et al.
(författare)
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How trophic interaction strength depends on traits : A conceptual framework for representing multidimensional trophic niche spaces
- 2010
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Ingår i: Theoretical Ecology. - : Springer Netrherlands. - 1874-1738 .- 1874-1746. ; 3:1, s. 13-24
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Tidskriftsartikel (refereegranskat)abstract
- A key problem in community ecology is to understand how individual-level traits give rise to population-level trophic interactions. Here, we propose a synthetic framework based on ecological considerations to address this question systematically. We derive a general functional form for the dependence of trophic interaction coefficients on trophically relevant quantitative traits of consumers and resources. The derived expression encompasses—and thus allows a unified comparison of—several functional forms previously proposed in the literature. Furthermore, we show how a community’s, potentially low-dimens ional, effective trophic niche space is related to its higher-dimensional phenotypic trait space. In this manner, we give ecological meaning to the notion of the “dimensionality of trophic niche space.” Our framework implies a method for directly measuring this dimensionality. We suggest a procedure for estimating the relevant parameters from empirical data and for verifying that such data matches the assumptions underlying our derivation.
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| 6. |
- Schipper, Aafke M., et al.
(författare)
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Contrasting changes in the abundance and diversity of North American bird assemblages from 1971 to 2010
- 2016
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 22:12, s. 3948-3959
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Tidskriftsartikel (refereegranskat)abstract
- Although it is generally recognized that global biodiversity is declining, few studies have examined long-term changes in multiple biodiversity dimensions simultaneously. In this study, we quantified and compared temporal changes in the abundance, taxonomic diversity, functional diversity, and phylogenetic diversity of bird assemblages, using roadside monitoring data of the North American Breeding Bird Survey from 1971 to 2010. We calculated 12 abundance and diversity metrics based on 5-year average abundances of 519 species for each of 768 monitoring routes. We did this for all bird species together as well as for four subgroups based on breeding habitat affinity (grassland, woodland, wetland, and shrubland breeders). The majority of the biodiversity metrics increased or remained constant over the study period, whereas the overall abundance of birds showed a pronounced decrease, primarily driven by declines of the most abundant species. These results highlight how stable or even increasing metrics of taxonomic, functional, or phylogenetic diversity may occur in parallel with substantial losses of individuals. We further found that patterns of change differed among the species subgroups, with both abundance and diversity increasing for woodland birds and decreasing for grassland breeders. The contrasting changes between abundance and diversity and among the breeding habitat groups underscore the relevance of a multifaceted approach to measuring biodiversity change. Our findings further stress the importance of monitoring the overall abundance of individuals in addition to metrics of taxonomic, functional, or phylogenetic diversity, thus confirming the importance of population abundance as an essential biodiversity variable.
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| 7. |
- Tam, Jamie C., et al.
(författare)
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Towards ecosystem-based management : identifying operational food-web indicators for marine ecosystems
- 2017
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 74:7, s. 2040-2052
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Tidskriftsartikel (refereegranskat)abstract
- Modern approaches to Ecosystem-Based Management and sustainable use of marine resources must account for the myriad of pressures (interspecies, human and environmental) affecting marine ecosystems. The network of feeding interactions between co-existing species and populations (food webs) are an important aspect of all marine ecosystems and biodiversity. Here we describe and discuss a process to evaluate the selection of operational food-web indicators for use in evaluating marine ecosystem status. This process brought together experts in food-web ecology, marine ecology, and resource management, to identify available indicators that can be used to inform marine management. Standard evaluation criteria (availability and quality of data, conceptual basis, communicability, relevancy to management) were implemented to identify practical food-web indicators ready for operational use and indicators that hold promise for future use in policy and management. The major attributes of the final suite of operational food-web indicators were structure and functioning. Indicators that represent resilience of the marine ecosystem were less developed. Over 60 potential food-web indicators were evaluated and the final selection of operational food-web indicators includes: the primary production required to sustain a fishery, the productivity of seabirds (or charismatic megafauna), zooplankton indicators, primary productivity, integrated trophic indicators, and the biomass of trophic guilds. More efforts should be made to develop thresholds-based reference points for achieving Good Environmental Status. There is also a need for international collaborations to develop indicators that will facilitate management in marine ecosystems used by multiple countries.
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