Predicting the ecological impacts of an alien invader: Experimental approaches reveal the trophic consequences of competition

Authors: Britton, J.R., Gutmann Roberts, C., Amat Trigo, F., Nolan, E.T. and De Santis, V.

Journal: Journal of Animal Ecology

Volume: 88

Issue: 7

Pages: 1066-1078

eISSN: 1365-2656

ISSN: 0021-8790

DOI: 10.1111/1365-2656.12996

Abstract:

Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. Whilst increased interspecific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity. The consequences of increased interspecific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms. Comparative functional responses revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from interspecific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species pairs by indirect effects. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

https://eprints.bournemouth.ac.uk/31836/

Source: Scopus

Predicting the ecological impacts of an alien invader: Experimental approaches reveal the trophic consequences of competition.

Authors: Britton, J.R., Gutmann Roberts, C., Amat Trigo, F., Nolan, E.T. and De Santis, V.

Journal: J Anim Ecol

Volume: 88

Issue: 7

Pages: 1066-1078

eISSN: 1365-2656

DOI: 10.1111/1365-2656.12996

Abstract:

Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. Whilst increased interspecific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity. The consequences of increased interspecific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms. Comparative functional responses revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from interspecific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species pairs by indirect effects. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

https://eprints.bournemouth.ac.uk/31836/

Source: PubMed

Predicting the ecological impacts of an alien invader: Experimental approaches reveal the trophic consequences of competition

Authors: Britton, J.R., Roberts, C.G., Amat Trigo, F., Nolan, E.T. and De Santis, V.

Journal: JOURNAL OF ANIMAL ECOLOGY

Volume: 88

Issue: 7

Pages: 1066-1078

eISSN: 1365-2656

ISSN: 0021-8790

DOI: 10.1111/1365-2656.12996

https://eprints.bournemouth.ac.uk/31836/

Source: Web of Science (Lite)

Predicting the ecological impacts of an alien invader: experimental approaches reveal the trophic consequences of competition

Authors: Britton, J.R., Gutmann Roberts, C., Amat Trigo, F., De Santis, V. and Nolan, E.

Journal: Journal of Animal Ecology

Publisher: Wiley-Blackwell

ISSN: 0021-8790

Abstract:

1. Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. While increased inter-specific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity.

2. The consequences of increased inter-specific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms.

3. CFRs revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant.

4. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from inter-specific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species-pairs by indirect effects.

5. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

https://eprints.bournemouth.ac.uk/31836/

Source: Manual

Predicting the ecological impacts of an alien invader: Experimental approaches reveal the trophic consequences of competition.

Authors: Britton, J.R., Gutmann Roberts, C., Amat Trigo, F., Nolan, E.T. and De Santis, V.

Journal: The Journal of animal ecology

Volume: 88

Issue: 7

Pages: 1066-1078

eISSN: 1365-2656

ISSN: 0021-8790

DOI: 10.1111/1365-2656.12996

Abstract:

Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. Whilst increased interspecific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity. The consequences of increased interspecific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms. Comparative functional responses revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from interspecific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species pairs by indirect effects. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

https://eprints.bournemouth.ac.uk/31836/

Source: Europe PubMed Central

Predicting the ecological impacts of an alien invader: experimental approaches reveal the trophic consequences of competition

Authors: Britton, J.R., Gutmann Roberts, C., Amat-Trigo, F. and de Santis, V.

Journal: Journal of Animal Ecology

Volume: 88

Issue: 7

Pages: 1066-1078

ISSN: 0021-8790

Abstract:

1. Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. While increased inter-specific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity. 2. The consequences of increased inter-specific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms. 3. CFRs revealed that compared to B. barbus, L. idus had significantly higher attack and consumption rates; cohabitation trials revealed B. barbus growth rates were depressed in sympatry with L. idus. For L. idus and S. cephalus, differences in their functional response parameters and growth rates were not significant. 4. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from inter-specific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species-pairs by indirect effects. 5. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

https://eprints.bournemouth.ac.uk/31836/

Source: BURO EPrints