Experimental evidence of competitive release in sympatric carnivores

Trewby, Iain D; Wilson, Gavin; Delahay, Richard J.; Walker, Neil J.; Young, Richard P.; Davison, John; Cheeseman, C. L.; Robertson, Pete; Gorman, M. L.; McDonald, Robbie A.

doi:10.1098/rsbl.2007.0516

Cited by 78 publications

(58 citation statements)

References 20 publications

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“…In addition, a growing body of field studies indicates that the phenomenon of mesopredator release is widespread among mammalian carnivore assemblages (e.g. Palomares et al 1995;Crooks & Soulé 1999;Trewby et al 2008) and appears to be particularly applicable to coexisting canids of differing body sizes such as dingoes and red foxes (Kamler et al 2003;Berger & Gese 2007). Given increasing support for the MRH and data on dingo -fox interactions (Newsome et al 2001;Letnic 2007;Johnson & Van Der Wal 2009; this study), we have no reason to believe that the outcomes of interactions between dingoes and foxes, and the prey of foxes, should not accord with the MRH.…”

Section: Discussion (A) the Effects Of Dingo Exclusionmentioning

confidence: 99%

Keystone effects of an alien top-predator stem extinctions of native mammals

et al. 2009

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Alien predators can have catastrophic effects on ecosystems and are thought to be much more harmful to biodiversity than their native counterparts. However, trophic cascade theory and the mesopredator release hypothesis predict that the removal of top predators will result in the reorganization of trophic webs and loss of biodiversity. Using field data collected throughout arid Australia, we provide evidence that removal of an alien top-predator, the dingo, has cascading effects through lower trophic levels. Dingo removal was linked to increased activity of herbivores and an invasive mesopredator, the red fox (Vulpes vulpes), and to the loss of grass cover and native species of small mammals. Using species distribution data, we predict that reintroducing or maintaining dingo populations would produce a net benefit for the conservation of threatened native mammals across greater than 2.42 Â 10 6 km 2 of Australia. Our study provides evidence that an alien top predator can assume a keystone role and be beneficial for biodiversity conservation, and also that mammalian carnivores more generally can generate strong trophic cascades in terrestrial ecosystems.

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Section: Discussion (A) the Effects Of Dingo Exclusionmentioning

confidence: 99%

Keystone effects of an alien top-predator stem extinctions of native mammals

et al. 2009

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“…Competitive interactions can be complex and shifts in their dynamics have resulted in unpredictable and sometimes profound impacts on lower trophic levels [3,4]. Compelling examples are emerging describing the deleterious impacts that subordinate predators, or mesopredators, inflict on prey species after being released from competition with a dominant predator [5][6][7][8][9][10]. Some instances of mesopredator release have yielded counterintuitive outcomes; for example, the removal of cats from an island resulted in a decline rather than an increase in the resident seabird colony because rats were released from regulation by cats, resulting in an increase in rat numbers and egg predation rates [4].…”

Section: Introductionmentioning

confidence: 99%

Could controlling mammalian carnivores lead to mesopredator release of carnivorous reptiles?

Sutherland¹,

Glen²,

Tores³

2010

Proc. R. Soc. B.

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Emerging evidence increasingly illustrates the importance of a holistic, rather than taxon-specific, approach to the study of ecological communities. Considerable resources are expended to manage both introduced and native mammalian carnivores to improve conservation outcomes; however, management can result in unforeseen and sometimes catastrophic outcomes. Varanid lizards are likely to be apex-or mesopredators, but being reptiles are rarely considered by managers and researchers when investigating the impacts of mammalian carnivore management. Instances of mesopredator release have been described for Varanus gouldii as a result of fox and cat management in Australia, with cascading effects on faunal community structure. A meta-analysis showing extensive dietary niche overlap between varanids, foxes and cats plus a review of experimental and circumstantial evidence suggests mesopredator release of V. gouldii and about five other medium to large species of varanid lizard is likely in other regions. This highlights the need for managers to adopt a whole-of-community approach when attempting to manage predators for sustained fauna conservation, and that additional research is required to elucidate whether mesopredator release of varanids is a widespread consequence of carnivore management, altering the intended faunal responses.

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“…Many plant communities are organized as transitive competitive hierarchies, in which superior competitors achieve the greatest abundance in the field (reviewed in Keddy 1990). Experimental studies of vertebrate (Heske et al 1994; Griffis and Jaeger 1998;Trewby et al 2008) and invertebrate (Race 1982;Kohler 1992;Andersen and Patel 1994) communities provide evidence for competitive release following the exclusion of a dominant, abundant species.…”

Section: Introductionmentioning

confidence: 99%

Predicting community structure of ground-foraging ant assemblages with Markov models of behavioral dominance

Wittman

Gotelli

2010

Oecologia

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Although interference competition is a conspicuous component of many animal communities, it is still uncertain whether the competitive ability of a species determines its relative abundance and patterns of association with other species. We used replicated arena tests to quantify behavioral dominance of eight common species of co-occurring ground-foraging ants in the Siskiyou Mountains of southern Oregon. We found that behavior recorded in laboratory assays was an accurate representation of a colony's ability to monopolize resources in the field. We used interaction frequencies from the behavioral tests to estimate transition probabilities in a simple Markov chain model to predict patterns of relative abundance in a metacommunity that is dominated by behavioral interactions. We also tested whether behavioral interactions between each pair of species could be used to predict patterns of species co-occurrence. We found that the Markov model did not accurately predict patterns of observed relative abundance on either the local or the regional scale. However, we did detect a significant negative correlation at the local scale in which behaviorally dominant species occupied relatively few baits. Pairwise behavioral data also did not predict species co-occurrence in any site. Although interference competition is a conspicuous process in ant communities, our results suggest that it may not contribute much to patterns of relative abundance and species co-occurrence in the system studied here. However, the negative correlation between behavioral dominance and bait occupancy at the local scale suggests that competition-colonization trade-offs may be important in resource acquisition and persistence of behaviorally subordinate species.

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Experimental evidence of competitive release in sympatric carnivores

Cited by 78 publications

References 20 publications

Keystone effects of an alien top-predator stem extinctions of native mammals

Keystone effects of an alien top-predator stem extinctions of native mammals

Could controlling mammalian carnivores lead to mesopredator release of carnivorous reptiles?

Predicting community structure of ground-foraging ant assemblages with Markov models of behavioral dominance

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