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Phylogenetic and trait-based assembly of arbuscular mycorrhizal fungal communities.

Maherali H, Klironomos JN - PLoS ONE (2012)

Bottom Line: The ability of AM fungal species to colonize soil did not influence co-existence.These results suggest that competition between closely related and functionally similar species for space on plant roots influences community assembly.Our results therefore also suggest that competition for niche space between closely related fungi is not the sole influence of mycorrhizal community structure in field situations, but may be of greater relative importance than other ecological mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada. maherali@uoguelph.ca

ABSTRACT
Both competition and environmental filtering are expected to influence the community structure of microbes, but there are few tests of the relative importance of these processes because trait data on these organisms is often difficult to obtain. Using phylogenetic and functional trait information, we tested whether arbuscular mycorrhizal (AM) fungal community composition in an old field was influenced by competitive exclusion and/or environmental filtering. Communities at the site were dominated by species from the most speciose family of AM fungi, the Glomeraceae, though species from two other lineages, the Acaulosporaceae and Gigasporaceae were also found. Despite the dominance of species from a single family, AM fungal species most frequently co-existed when they were distantly related and when they differed in the ability to colonize root space on host plants. The ability of AM fungal species to colonize soil did not influence co-existence. These results suggest that competition between closely related and functionally similar species for space on plant roots influences community assembly. Nevertheless, in a substantial minority of cases communities were phylogenetically clustered, indicating that closely related species could also co-occur, as would be expected if i) the environment restricted community membership to single functional type or ii) competition among functionally similar species was weak. Our results therefore also suggest that competition for niche space between closely related fungi is not the sole influence of mycorrhizal community structure in field situations, but may be of greater relative importance than other ecological mechanisms.

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A phylogeny of AM fungi found in the 50 m×50 m sampling grid, along with trait values for Root Colonization and Hyphal Length mapped to each taxon.Both traits were phylogenetically conserved.
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pone-0036695-g003: A phylogeny of AM fungi found in the 50 m×50 m sampling grid, along with trait values for Root Colonization and Hyphal Length mapped to each taxon.Both traits were phylogenetically conserved.

Mentions: AM fungal functional traits were conserved. We detected a significant tree wide phylogenetic signal for the extent of root colonization (contrast variance = 0.497, P = 0.002) and hyphal colonization of soil (contrast variance = 163.2, P = 0.004). The bulk of extant trait variation was accounted for by deep divergences in the phylogeny (Figure 3). For root colonization, the divergence between the Glomerales and Diversisporales had the largest contribution index (CI) accounting for 83% of extant trait variation (Node A, P = 0.001). For hyphal length colonization of soil, the divergence between Gigasporaceae and Acaulosporaceae within the Diversisporales had the largest CI, accounting for 84% of extant trait variation (Node B, P = 0.001).


Phylogenetic and trait-based assembly of arbuscular mycorrhizal fungal communities.

Maherali H, Klironomos JN - PLoS ONE (2012)

A phylogeny of AM fungi found in the 50 m×50 m sampling grid, along with trait values for Root Colonization and Hyphal Length mapped to each taxon.Both traits were phylogenetically conserved.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351463&req=5

pone-0036695-g003: A phylogeny of AM fungi found in the 50 m×50 m sampling grid, along with trait values for Root Colonization and Hyphal Length mapped to each taxon.Both traits were phylogenetically conserved.
Mentions: AM fungal functional traits were conserved. We detected a significant tree wide phylogenetic signal for the extent of root colonization (contrast variance = 0.497, P = 0.002) and hyphal colonization of soil (contrast variance = 163.2, P = 0.004). The bulk of extant trait variation was accounted for by deep divergences in the phylogeny (Figure 3). For root colonization, the divergence between the Glomerales and Diversisporales had the largest contribution index (CI) accounting for 83% of extant trait variation (Node A, P = 0.001). For hyphal length colonization of soil, the divergence between Gigasporaceae and Acaulosporaceae within the Diversisporales had the largest CI, accounting for 84% of extant trait variation (Node B, P = 0.001).

Bottom Line: The ability of AM fungal species to colonize soil did not influence co-existence.These results suggest that competition between closely related and functionally similar species for space on plant roots influences community assembly.Our results therefore also suggest that competition for niche space between closely related fungi is not the sole influence of mycorrhizal community structure in field situations, but may be of greater relative importance than other ecological mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada. maherali@uoguelph.ca

ABSTRACT
Both competition and environmental filtering are expected to influence the community structure of microbes, but there are few tests of the relative importance of these processes because trait data on these organisms is often difficult to obtain. Using phylogenetic and functional trait information, we tested whether arbuscular mycorrhizal (AM) fungal community composition in an old field was influenced by competitive exclusion and/or environmental filtering. Communities at the site were dominated by species from the most speciose family of AM fungi, the Glomeraceae, though species from two other lineages, the Acaulosporaceae and Gigasporaceae were also found. Despite the dominance of species from a single family, AM fungal species most frequently co-existed when they were distantly related and when they differed in the ability to colonize root space on host plants. The ability of AM fungal species to colonize soil did not influence co-existence. These results suggest that competition between closely related and functionally similar species for space on plant roots influences community assembly. Nevertheless, in a substantial minority of cases communities were phylogenetically clustered, indicating that closely related species could also co-occur, as would be expected if i) the environment restricted community membership to single functional type or ii) competition among functionally similar species was weak. Our results therefore also suggest that competition for niche space between closely related fungi is not the sole influence of mycorrhizal community structure in field situations, but may be of greater relative importance than other ecological mechanisms.

Show MeSH