Limits...
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.

Show MeSH
The frequency of AM fungal species across the 50 m×50 m sampled grid and a species rarefaction curve (inset).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3351463&req=5

pone-0036695-g001: The frequency of AM fungal species across the 50 m×50 m sampled grid and a species rarefaction curve (inset).

Mentions: There were sporulating AM fungal species in 2532 of the 2601 sampling grid points and species richness in these communities ranged from 1 to 8 taxa. There were 2151 communities for which mean nearest phylogenetic taxon distance (MNTD) could be calculated (i.e., where richness was ≥2). A total of 15 species spanning 3 families were identified (Figure 1, 2), 57% were Glomeraceae, 24% were Acaulosporaceae and 19% were Gigasporaceae. Our sampling protocol was sufficient to reach saturation for number of species existing at the site (Figure 1, inset). Ten of 14 species for which Morisita’s index (Iδ) could be calculated had values >1, indicating a clumped distribution pattern (Figure 2). The four most abundant species (Figure 1), however, had values that were ∼1 or <1, indicating either a random or even distribution pattern, respectively.


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

Maherali H, Klironomos JN - PLoS ONE (2012)

The frequency of AM fungal species across the 50 m×50 m sampled grid and a species rarefaction curve (inset).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0036695-g001: The frequency of AM fungal species across the 50 m×50 m sampled grid and a species rarefaction curve (inset).
Mentions: There were sporulating AM fungal species in 2532 of the 2601 sampling grid points and species richness in these communities ranged from 1 to 8 taxa. There were 2151 communities for which mean nearest phylogenetic taxon distance (MNTD) could be calculated (i.e., where richness was ≥2). A total of 15 species spanning 3 families were identified (Figure 1, 2), 57% were Glomeraceae, 24% were Acaulosporaceae and 19% were Gigasporaceae. Our sampling protocol was sufficient to reach saturation for number of species existing at the site (Figure 1, inset). Ten of 14 species for which Morisita’s index (Iδ) could be calculated had values >1, indicating a clumped distribution pattern (Figure 2). The four most abundant species (Figure 1), however, had values that were ∼1 or <1, indicating either a random or even distribution pattern, respectively.

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