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Strong invaders are strong defenders: implications for the resistance of invaded communities
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Swedish University of Agriculture Sciences, Department of Forest Vegetation Ecology.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
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2016 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 19, no 4, 487-494 p.Article in journal (Refereed) Published
Abstract [en]

Many ecosystems receive a steady stream of non-native species. How biotic resistance develops over time in these ecosystems will depend on how established invaders contribute to subsequent resistance. If invasion success and defence capacity (i.e. contribution to resistance) are correlated, then community resistance should increase as species accumulate. If successful invaders also cause most impact (through replacing native species with low defence capacity) then the effect will be even stronger. If successful invaders instead have weak defence capacity or even facilitative attributes, then resistance should decrease with time, as proposed by the invasional meltdown hypothesis. We analysed 1157 introductions of freshwater fish in Swedish lakes and found that species' invasion success was positively correlated with their defence capacity and impact, suggesting that these communities will develop stronger resistance over time. These insights can be used to identify scenarios where invading species are expected to cause large impact.

Place, publisher, year, edition, pages
2016. Vol. 19, no 4, 487-494 p.
Keyword [en]
biotic resistance, freshwater fish, introductions, interaction hierarchies, strong invaders, strong defenders, invasions
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-110248DOI: 10.1111/ele.12586ISI: 000372654800015OAI: oai:DiVA.org:umu-110248DiVA: diva2:861755
Note

Originally included in thesis in manuscript form.

Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2016-06-02Bibliographically approved
In thesis
1. Biotic resistance in freshwater fish communities
Open this publication in new window or tab >>Biotic resistance in freshwater fish communities
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Invasions of non-native species cause problems in ecosystems worldwide, and despite the extensive effort that has been put into research about invasions, we still lack a good understanding for why some, but not other, communities resist these invasions. In this doctoral thesis I test hypotheses on biotic resistance using a large dataset of more than 1000 both failed and successful introductions of freshwater fish into Swedish lakes. We have found that the classic species richness hypothesis is a poor descriptor of introduction success because it fails to acknowledge that resident species contribute to the resistance in different ways. We developed a new measure of biotic resistance, the weighted species richness, which takes into account that the resident species contributes to the resistance with different strength and sign. Further, we correlated performance traits of species in their role as an invader and as a resident species to predict how the biotic resistance of these communities would develop over time. We found a positive correlation between performance traits: Some species have high introduction success, they make a large contribution to the resistance, and they cause extinctions when introduced but do not go extinct themselves when other species establishes, whereas other species are weak performers in these respects. Thus, the biotic resistance of these communities should grow stronger as non-native species accumulates. These results give us clues about what type of communities that should be most sensitive to further invasions, i.e., communities harboring species weak performers. 

My results show that the biotic resistance of communities is an important factor in determining invasibility of a community. They also show that methods for quantifying resistance must take into account how interactions are structured in nature. What determine the biotic resistance of a community is the type of interactions that the resident species have with the invader and not the species richness of the community.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2015. 26 p.
Keyword
biotic resistance, freshwater fish, introductions, invasions, invasion success, invasibility, invasiveness, species richness, saturation, species identity, weighted species richness
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-110251 (URN)978-91-7601-326-7 (ISBN)
Public defence
2015-11-12, Naturvetarhuset, N320, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2015-10-22 Created: 2015-10-19 Last updated: 2015-11-13Bibliographically approved

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Henriksson, AnnaTrygg, JohanDiehl, SebastianEnglund, Göran
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Department of Ecology and Environmental SciencesDepartment of Chemistry
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