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Loss of functionally unique species may gradually undermine ecosystems


O'Gorman, E J; Yearsley, J M; Crowe, T P; Emmerson, M C; Jacob, U; Petchey, O L (2011). Loss of functionally unique species may gradually undermine ecosystems. Proceedings of the Royal Society B: Biological Sciences, 278(1713):1886-1893.

Abstract

Functionally unique species contribute to the functional diversity of natural systems, often enhancing
ecosystem functioning. An abundance of weakly interacting species increases stability in natural systems,
suggesting that loss of weakly linked species may reduce stability. Any link between the functional uniqueness
of a species and the strength of its interactions in a food web could therefore have simultaneous
effects on ecosystem functioning and stability. Here, we analyse patterns in 213 real food webs and
show that highly unique species consistently tend to have the weakest mean interaction strength per
unit biomass in the system. This relationship is not a simple consequence of the interdependence of
both measures on body size and appears to be driven by the empirical pattern of size structuring in
aquatic systems and the trophic position of each species in the web. Food web resolution also has an
important effect, with aggregation of species into higher taxonomic groups producing a much weaker
relationship. Food webs with fewer unique and less weakly interacting species also show significantly
greater variability in their levels of primary production. Thus, the loss of highly unique, weakly interacting
species may eventually lead to dramatic state changes and unpredictable levels of ecosystem functioning.

Abstract

Functionally unique species contribute to the functional diversity of natural systems, often enhancing
ecosystem functioning. An abundance of weakly interacting species increases stability in natural systems,
suggesting that loss of weakly linked species may reduce stability. Any link between the functional uniqueness
of a species and the strength of its interactions in a food web could therefore have simultaneous
effects on ecosystem functioning and stability. Here, we analyse patterns in 213 real food webs and
show that highly unique species consistently tend to have the weakest mean interaction strength per
unit biomass in the system. This relationship is not a simple consequence of the interdependence of
both measures on body size and appears to be driven by the empirical pattern of size structuring in
aquatic systems and the trophic position of each species in the web. Food web resolution also has an
important effect, with aggregation of species into higher taxonomic groups producing a much weaker
relationship. Food webs with fewer unique and less weakly interacting species also show significantly
greater variability in their levels of primary production. Thus, the loss of highly unique, weakly interacting
species may eventually lead to dramatic state changes and unpredictable levels of ecosystem functioning.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:German
Date:2011
Deposited On:25 Nov 2011 12:48
Last Modified:10 Aug 2017 06:16
Publisher:Royal Society of London
ISSN:0962-8452
Publisher DOI:https://doi.org/10.1098/rspb.2010.2036
PubMed ID:21106593

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