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Untangling the fungal niche: the trait-based approach.

Crowther TW, Maynard DS, Crowther TR, Peccia J, Smith JR, Bradford MA - Front Microbiol (2014)

Bottom Line: Given that the survival of a fungus in a given environment is contingent on its ability to tolerate antagonistic competitors, measuring variation in combat trait expression along environmental gradients provides a means of elucidating realized, from fundamental niche spaces.We conclude that, using a trait-based understanding of how niche processes structure fungal communities across time and space, we can ultimately link communities with ecosystem functioning.Our trait-based framework highlights fundamental uncertainties that require testing in the fungal system, given their potential to uncover general mechanisms in fungal ecology.

View Article: PubMed Central - PubMed

Affiliation: Yale School of Forestry and Environmental Studies, Yale University New Haven, CT, USA.

ABSTRACT
Fungi are prominent components of most terrestrial ecosystems, both in terms of biomass and ecosystem functioning, but the hyper-diverse nature of most communities has obscured the search for unifying principles governing community organization. In particular, unlike plants and animals, observational studies provide little evidence for the existence of niche processes in structuring fungal communities at broad spatial scales. This limits our capacity to predict how communities, and their functioning, vary across landscapes. We outline how a shift in focus, from taxonomy toward functional traits, might prove to be valuable in the search for general patterns in fungal ecology. We build on theoretical advances in plant and animal ecology to provide an empirical framework for a trait-based approach in fungal community ecology. Drawing upon specific characteristics of the fungal system, we highlight the significance of drought stress and combat in structuring free-living fungal communities. We propose a conceptual model to formalize how trade-offs between stress-tolerance and combative dominance are likely to organize communities across environmental gradients. Given that the survival of a fungus in a given environment is contingent on its ability to tolerate antagonistic competitors, measuring variation in combat trait expression along environmental gradients provides a means of elucidating realized, from fundamental niche spaces. We conclude that, using a trait-based understanding of how niche processes structure fungal communities across time and space, we can ultimately link communities with ecosystem functioning. Our trait-based framework highlights fundamental uncertainties that require testing in the fungal system, given their potential to uncover general mechanisms in fungal ecology.

No MeSH data available.


Related in: MedlinePlus

The effect of reduced water activity (the partial vapor pressure of a substance) and decreased temperature on fungal combative ability. Data are adapted from Tables 3,6 in Magan and Lacey (1984). Fungi that are the most combative under optimal conditions (25°C and water activity [Aw] of 0.98) have a greater reduction in competitive ability under reduced water activity (Aw = 0.90) than under reduced temperature conditions. Index of Dominance (ID) was assessed for each fungus by quantifying the outcomes of all pairwise competitions, with higher numbers indicating more competitive fungi (see Magan and Lacey, 1984 for details). (a) “Low water activity” refers to Aw = 0.90, holding temperature constant at 25°C (6 of the 16 fungi had missing ID values at this water activity level); (b) “Low temperature” refers to 15°C, holding Aw constant at 0.98. Relative ID values were calculated by dividing each fungus' ID by the maximum ID across all species. R2adj and corresponding p-values were obtained by simple linear regression of relative ID vs. proportional change in ID.
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Figure 3: The effect of reduced water activity (the partial vapor pressure of a substance) and decreased temperature on fungal combative ability. Data are adapted from Tables 3,6 in Magan and Lacey (1984). Fungi that are the most combative under optimal conditions (25°C and water activity [Aw] of 0.98) have a greater reduction in competitive ability under reduced water activity (Aw = 0.90) than under reduced temperature conditions. Index of Dominance (ID) was assessed for each fungus by quantifying the outcomes of all pairwise competitions, with higher numbers indicating more competitive fungi (see Magan and Lacey, 1984 for details). (a) “Low water activity” refers to Aw = 0.90, holding temperature constant at 25°C (6 of the 16 fungi had missing ID values at this water activity level); (b) “Low temperature” refers to 15°C, holding Aw constant at 0.98. Relative ID values were calculated by dividing each fungus' ID by the maximum ID across all species. R2adj and corresponding p-values were obtained by simple linear regression of relative ID vs. proportional change in ID.

Mentions: The tendency of drought stress to alter these combative hierarchies (Boddy, 2000) provides strong evidence for a trade-off between drought stress and combative ability. Indeed, Magan and Lacey (1984) estimated an index of dominance (ID: a numerical score for combative ability) for multiple competing fungi in pairwise combinations in agar cultures, showing that both drought and temperature stress can alter the fungal dominance hierarchy. Re-analysis of this initial data reveals that the magnitude of the drought effect correlated strongly with initial combative ability (recorded under optimal conditions); the most antagonistic species experience the greatest competitive losses during drought stress. In contrast, whilst there was some evidence that temperature stress drives a similar relationship, the trade-off is substantially weaker, and the negative effects of heat stress are relatively consistent across all species (Figure 3; Magan and Lacey, 1984). Based on the strength and consistency of the relationship between drought-tolerance and combative ability (Magan and Lacey, 1984; Lennon et al., 2012), we hypothesize that this dominance-tolerance trade-off is likely to be a predominant mechanism structuring free-living fungal communities in predictable ways across time and space.


Untangling the fungal niche: the trait-based approach.

Crowther TW, Maynard DS, Crowther TR, Peccia J, Smith JR, Bradford MA - Front Microbiol (2014)

The effect of reduced water activity (the partial vapor pressure of a substance) and decreased temperature on fungal combative ability. Data are adapted from Tables 3,6 in Magan and Lacey (1984). Fungi that are the most combative under optimal conditions (25°C and water activity [Aw] of 0.98) have a greater reduction in competitive ability under reduced water activity (Aw = 0.90) than under reduced temperature conditions. Index of Dominance (ID) was assessed for each fungus by quantifying the outcomes of all pairwise competitions, with higher numbers indicating more competitive fungi (see Magan and Lacey, 1984 for details). (a) “Low water activity” refers to Aw = 0.90, holding temperature constant at 25°C (6 of the 16 fungi had missing ID values at this water activity level); (b) “Low temperature” refers to 15°C, holding Aw constant at 0.98. Relative ID values were calculated by dividing each fungus' ID by the maximum ID across all species. R2adj and corresponding p-values were obtained by simple linear regression of relative ID vs. proportional change in ID.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215788&req=5

Figure 3: The effect of reduced water activity (the partial vapor pressure of a substance) and decreased temperature on fungal combative ability. Data are adapted from Tables 3,6 in Magan and Lacey (1984). Fungi that are the most combative under optimal conditions (25°C and water activity [Aw] of 0.98) have a greater reduction in competitive ability under reduced water activity (Aw = 0.90) than under reduced temperature conditions. Index of Dominance (ID) was assessed for each fungus by quantifying the outcomes of all pairwise competitions, with higher numbers indicating more competitive fungi (see Magan and Lacey, 1984 for details). (a) “Low water activity” refers to Aw = 0.90, holding temperature constant at 25°C (6 of the 16 fungi had missing ID values at this water activity level); (b) “Low temperature” refers to 15°C, holding Aw constant at 0.98. Relative ID values were calculated by dividing each fungus' ID by the maximum ID across all species. R2adj and corresponding p-values were obtained by simple linear regression of relative ID vs. proportional change in ID.
Mentions: The tendency of drought stress to alter these combative hierarchies (Boddy, 2000) provides strong evidence for a trade-off between drought stress and combative ability. Indeed, Magan and Lacey (1984) estimated an index of dominance (ID: a numerical score for combative ability) for multiple competing fungi in pairwise combinations in agar cultures, showing that both drought and temperature stress can alter the fungal dominance hierarchy. Re-analysis of this initial data reveals that the magnitude of the drought effect correlated strongly with initial combative ability (recorded under optimal conditions); the most antagonistic species experience the greatest competitive losses during drought stress. In contrast, whilst there was some evidence that temperature stress drives a similar relationship, the trade-off is substantially weaker, and the negative effects of heat stress are relatively consistent across all species (Figure 3; Magan and Lacey, 1984). Based on the strength and consistency of the relationship between drought-tolerance and combative ability (Magan and Lacey, 1984; Lennon et al., 2012), we hypothesize that this dominance-tolerance trade-off is likely to be a predominant mechanism structuring free-living fungal communities in predictable ways across time and space.

Bottom Line: Given that the survival of a fungus in a given environment is contingent on its ability to tolerate antagonistic competitors, measuring variation in combat trait expression along environmental gradients provides a means of elucidating realized, from fundamental niche spaces.We conclude that, using a trait-based understanding of how niche processes structure fungal communities across time and space, we can ultimately link communities with ecosystem functioning.Our trait-based framework highlights fundamental uncertainties that require testing in the fungal system, given their potential to uncover general mechanisms in fungal ecology.

View Article: PubMed Central - PubMed

Affiliation: Yale School of Forestry and Environmental Studies, Yale University New Haven, CT, USA.

ABSTRACT
Fungi are prominent components of most terrestrial ecosystems, both in terms of biomass and ecosystem functioning, but the hyper-diverse nature of most communities has obscured the search for unifying principles governing community organization. In particular, unlike plants and animals, observational studies provide little evidence for the existence of niche processes in structuring fungal communities at broad spatial scales. This limits our capacity to predict how communities, and their functioning, vary across landscapes. We outline how a shift in focus, from taxonomy toward functional traits, might prove to be valuable in the search for general patterns in fungal ecology. We build on theoretical advances in plant and animal ecology to provide an empirical framework for a trait-based approach in fungal community ecology. Drawing upon specific characteristics of the fungal system, we highlight the significance of drought stress and combat in structuring free-living fungal communities. We propose a conceptual model to formalize how trade-offs between stress-tolerance and combative dominance are likely to organize communities across environmental gradients. Given that the survival of a fungus in a given environment is contingent on its ability to tolerate antagonistic competitors, measuring variation in combat trait expression along environmental gradients provides a means of elucidating realized, from fundamental niche spaces. We conclude that, using a trait-based understanding of how niche processes structure fungal communities across time and space, we can ultimately link communities with ecosystem functioning. Our trait-based framework highlights fundamental uncertainties that require testing in the fungal system, given their potential to uncover general mechanisms in fungal ecology.

No MeSH data available.


Related in: MedlinePlus