Ecological integration of alien species into a tree-parasitic fungus network
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The diversification of species and their interactions during the course of evolution has produced ecological networks with a complex topology. This topology influences the current functioning of ecosystems. It is therefore important to investigate whether the species introduced recently by human activities have merged seamlessly into recipient ecological networks by developing interactions quantitatively and qualitatively similar to those of native species, or whether their establishment has altered the topology of the networks. We tackled this issue in the case of a well resolved interaction network between 51 forest tree taxa and 154 pathogenic fungal species. We found that alien and native species with similar phylogenetic histories and life-history strategies had similar types and numbers of interactions. Our results also suggest that the clustered architecture of the network has not been altered by the integration of alien species. It therefore seems that a few centuries have been sufficient for the network to assimilate the newly introduced species. This rapid integration was unexpected for a plant-pathogen network, because selection acts continually on plants, favouring the emergence of defences against new pathogens and impeding the development of new interactions. However, it was recently shown that perturbation of the structure of ecological networks might be overlooked if species interactions are not quantified. The tree-parasitic fungus network considered in this study is binary. We might therefore end up with different results by using quantitative data.
KeywordsAlien species Host-parasite interactions Trees Fungi Ecological networks Random graphs
We thank the Département Santé des Forêts (DSF) for allowing us to use their database and the French research consortium Interactions Biotiques dans les communautés (GDR ComEvol) for funding. We also thank Julie Sappa (Alex Edelman & Associates) for language revision.
- Bertheau C, Brockerhoff EG, Roux-Morabito G, Lieutier F, Jactel H (2010). Novel insect-tree associations resulting from accidental and intentional biological ‘invasions’: a meta-analysis of effects on insect fitness. Ecol Lett (in press)Google Scholar
- Desprez-Loustau ML (2009) The alien fungi of Europe. In: Nentwig W, Hulme P, Pysek P, Vila M (eds) Handbook of alien species in Europe. Springer, Berlin, p 400Google Scholar
- Mielke PW, Berry KJ (2001) Permutation methods: a distance function approach. Springer, New YorkGoogle Scholar
- Oksanen J, Kindt R, Legendre P et al (2006) Vegan: community ecology package version 1.8-3. R package URL http://www.R-project.org
- Picard F, Miele V, Daudin JJ, et al (2009) Deciphering the connectivity structure of biological networks using MixNet. BMC BioinformaticsGoogle Scholar
- SAS/STAT (2000) SAS Institute Inc., SAS OnlineDoc, version 8. SAS Institute Inc, CaryGoogle Scholar
- Vitousek PM, Dantonio CM, Loope LL et al (1996) Biological invasions as global environmental change. Am Sci 84:468–478Google Scholar