Exotic species richness and native species endemism increase the impact of exotic species on islands

Walsh, Jessica C., Venter, Oscar, Watson, James E.M., Fuller, Richard A., Blackburn, Tim M. and Possingham, Hugh P. (2012) Exotic species richness and native species endemism increase the impact of exotic species on islands. Global Ecology and Biogeography, 21 8: 841-850. doi:10.1111/j.1466-8238.2011.00724.x

Author Walsh, Jessica C.
Venter, Oscar
Watson, James E.M.
Fuller, Richard A.
Blackburn, Tim M.
Possingham, Hugh P.
Title Exotic species richness and native species endemism increase the impact of exotic species on islands
Journal name Global Ecology and Biogeography   Check publisher's open access policy
ISSN 1466-822X
Publication date 2012
Year available 2011
Sub-type Article (original research)
DOI 10.1111/j.1466-8238.2011.00724.x
Open Access Status
Volume 21
Issue 8
Start page 841
End page 850
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Collection year 2012
Language eng
Formatted abstract
Aim: Exotic species pose one of the most significant threats to biodiversity, especially on islands. The impacts of exotic species vary in severity among islands, yet little is known about what makes some islands more susceptible than others. Here we determine which characteristics of an island influence how severely exotic species affect its native biota.

: We studied 65 islands and archipelagos from around the world, ranging from latitude 65°N to 54°S.

Methods: We compiled a global database of 10 island characteristics for 65 islands and determined the relative importance of each characteristic in predicting the impact of exotic species using multivariate modelling and hierarchical partitioning. We defined the impact of exotic species as the number of bird, amphibian and mammal (BAM) species listed by the International Union for Conservation of Nature (IUCN) as threatened by exotics, relative to the total number of BAM species on that island.

: We found that the impact of exotic species is more severe on islands with more exotic species and a greater proportion of native species that are endemic. Unexpectedly, the level of anthropogenic disturbance did not influence an island's susceptibility to the impacts of exotic species.

Main conclusions: By coupling our results with studies on the introduction and establishment of exotic species, we conclude that colonization pressure, or invasion opportunities, influences all stages of the invasion process. However, species endemism, the other important factor determining the impact of exotic species, is not known to contribute to introduction and establishment success on islands. This demonstrates that different factors correlate with the initial stages of the invasion process and the subsequent impacts of those invaders, highlighting the importance of studying the impacts of exotic species directly. Our study helps identify islands that are at risk of impact by exotics and where investment should focus on preventing further invasions.
Keyword Anthropogenic disturbance
Colonization pressure
Exotic species
Extinction probability
IUCN Red List
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online: 11 November 2011.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 21 Mar 2012, 19:27:01 EST by Dr Richard Fuller on behalf of School of Biological Sciences