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Architecture of an antagonistic tree/fungus network: the asymmetric influence of past evolutionary history.

Vacher C, Piou D, Desprez-Loustau ML - PLoS ONE (2008)

Bottom Line: Unlike compartmentalization, nestedness did not reflect any consistent phylogenetic signal.Overall, our analyses emphasized how the current complexity of ecological networks results from the diversification of the species and their interactions over evolutionary times.They confirmed that the current architecture of ecological networks is not only dependent on recent ecological processes.

View Article: PubMed Central - PubMed

Affiliation: INRA [corrected] UMR1202 Biodiversité Gènes et Communautés, Villenave d'Ornon, France. cvacher@bordeaux.inra.fr

ABSTRACT

Background: Compartmentalization and nestedness are common patterns in ecological networks. The aim of this study was to elucidate some of the processes shaping these patterns in a well resolved network of host/pathogen interactions.

Methodology/principal findings: Based on a long-term (1972-2005) survey of forest health at the regional scale (all French forests; 15 million ha), we uncovered an almost fully connected network of 51 tree taxa and 157 parasitic fungal species. Our analyses revealed that the compartmentalization of the network maps out the ancient evolutionary history of seed plants, but not the ancient evolutionary history of fungal species. The very early divergence of the major fungal phyla may account for this asymmetric influence of past evolutionary history. Unlike compartmentalization, nestedness did not reflect any consistent phylogenetic signal. Instead, it seemed to reflect the ecological features of the current species, such as the relative abundance of tree species and the life-history strategies of fungal pathogens. We discussed how the evolution of host range in fungal species may account for the observed nested patterns.

Conclusion/significance: Overall, our analyses emphasized how the current complexity of ecological networks results from the diversification of the species and their interactions over evolutionary times. They confirmed that the current architecture of ecological networks is not only dependent on recent ecological processes.

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Related in: MedlinePlus

Comparison of the major pathogenic types (C: canker agents, OP: obligate biotroph parasites, RDF: root decay fungi, SDF: stem decay fungi, SF: strict foliar necrotroph parasites).Bars indicate standard errors of the means. (A) For the number of interactions per species. (B) For the number of tree groups linked together. Two tree taxa belong to the same group if they belong to the same network compartment. (C) For the rank in the network's largest connected component after rearrangement for nestedness.
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pone-0001740-g004: Comparison of the major pathogenic types (C: canker agents, OP: obligate biotroph parasites, RDF: root decay fungi, SDF: stem decay fungi, SF: strict foliar necrotroph parasites).Bars indicate standard errors of the means. (A) For the number of interactions per species. (B) For the number of tree groups linked together. Two tree taxa belong to the same group if they belong to the same network compartment. (C) For the rank in the network's largest connected component after rearrangement for nestedness.

Mentions: Life-history strategy had a significant effect on the total number of interactions per fungal species (Kruskal-Wallis rank sum tests; χ2 = 11.5, df = 4, p-value = 0.021) and the number of tree groups linked together by fungal species (Kruskal-Wallis rank sum tests; χ2 = 21.5, df = 4, p-value<0.001). Root decay fungi had the largest host range: they had the highest mean number of host taxa (Fig. 4A) and linked together the largest number of network compartments (Fig. 4B).


Architecture of an antagonistic tree/fungus network: the asymmetric influence of past evolutionary history.

Vacher C, Piou D, Desprez-Loustau ML - PLoS ONE (2008)

Comparison of the major pathogenic types (C: canker agents, OP: obligate biotroph parasites, RDF: root decay fungi, SDF: stem decay fungi, SF: strict foliar necrotroph parasites).Bars indicate standard errors of the means. (A) For the number of interactions per species. (B) For the number of tree groups linked together. Two tree taxa belong to the same group if they belong to the same network compartment. (C) For the rank in the network's largest connected component after rearrangement for nestedness.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2254192&req=5

pone-0001740-g004: Comparison of the major pathogenic types (C: canker agents, OP: obligate biotroph parasites, RDF: root decay fungi, SDF: stem decay fungi, SF: strict foliar necrotroph parasites).Bars indicate standard errors of the means. (A) For the number of interactions per species. (B) For the number of tree groups linked together. Two tree taxa belong to the same group if they belong to the same network compartment. (C) For the rank in the network's largest connected component after rearrangement for nestedness.
Mentions: Life-history strategy had a significant effect on the total number of interactions per fungal species (Kruskal-Wallis rank sum tests; χ2 = 11.5, df = 4, p-value = 0.021) and the number of tree groups linked together by fungal species (Kruskal-Wallis rank sum tests; χ2 = 21.5, df = 4, p-value<0.001). Root decay fungi had the largest host range: they had the highest mean number of host taxa (Fig. 4A) and linked together the largest number of network compartments (Fig. 4B).

Bottom Line: Unlike compartmentalization, nestedness did not reflect any consistent phylogenetic signal.Overall, our analyses emphasized how the current complexity of ecological networks results from the diversification of the species and their interactions over evolutionary times.They confirmed that the current architecture of ecological networks is not only dependent on recent ecological processes.

View Article: PubMed Central - PubMed

Affiliation: INRA [corrected] UMR1202 Biodiversité Gènes et Communautés, Villenave d'Ornon, France. cvacher@bordeaux.inra.fr

ABSTRACT

Background: Compartmentalization and nestedness are common patterns in ecological networks. The aim of this study was to elucidate some of the processes shaping these patterns in a well resolved network of host/pathogen interactions.

Methodology/principal findings: Based on a long-term (1972-2005) survey of forest health at the regional scale (all French forests; 15 million ha), we uncovered an almost fully connected network of 51 tree taxa and 157 parasitic fungal species. Our analyses revealed that the compartmentalization of the network maps out the ancient evolutionary history of seed plants, but not the ancient evolutionary history of fungal species. The very early divergence of the major fungal phyla may account for this asymmetric influence of past evolutionary history. Unlike compartmentalization, nestedness did not reflect any consistent phylogenetic signal. Instead, it seemed to reflect the ecological features of the current species, such as the relative abundance of tree species and the life-history strategies of fungal pathogens. We discussed how the evolution of host range in fungal species may account for the observed nested patterns.

Conclusion/significance: Overall, our analyses emphasized how the current complexity of ecological networks results from the diversification of the species and their interactions over evolutionary times. They confirmed that the current architecture of ecological networks is not only dependent on recent ecological processes.

Show MeSH
Related in: MedlinePlus