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The importance of spatial heterogeneity and self-restraint on mutualism stability - a quantitative review.

Wang RW, Dunn DW, Luo J, He JZ, Shi L - Sci Rep (2015)

Bottom Line: However, when the data were split according to four categories of host: 1) cnidarian corals, 2) woody plants, 3) herbaceous plants, and 4) insects, a significantly positive effect in corals was revealed.The trends for the remaining three categories did not significantly differ to zero.Our results suggest that stability in mutualisms requires alternative processes, or mechanisms in addition to, spatial heterogeneity of hosts and/or 'self-restraint' of symbionts.

View Article: PubMed Central - PubMed

Affiliation: Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an, 710072, China.

ABSTRACT
Understanding the factors that enable mutualisms to evolve and to subsequently remain stable over time, is essential to fully understand patterns of global biodiversity and for evidence based conservation policy. Theoretically, spatial heterogeneity of mutualists, through increased likelihood of fidelity between cooperative partners in structured populations, and 'self-restraint' of symbionts, due to selection against high levels of virulence leading to short-term host overexploitation, will result in either a positive correlation between the reproductive success of both mutualists prior to the total exploitation of any host resource or no correlation after any host resource has been fully exploited. A quantitative review by meta-analysis on the results of 96 studies from 35 papers, showed no evidence of a significant fitness correlation between mutualists across a range of systems that captured much taxonomic diversity. However, when the data were split according to four categories of host: 1) cnidarian corals, 2) woody plants, 3) herbaceous plants, and 4) insects, a significantly positive effect in corals was revealed. The trends for the remaining three categories did not significantly differ to zero. Our results suggest that stability in mutualisms requires alternative processes, or mechanisms in addition to, spatial heterogeneity of hosts and/or 'self-restraint' of symbionts.

No MeSH data available.


Funnel plot of the effect size, split by host type: Woody plant (*), Insect (o), Herbaceous plant (∇), and Coral (×).
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f2: Funnel plot of the effect size, split by host type: Woody plant (*), Insect (o), Herbaceous plant (∇), and Coral (×).

Mentions: After examining the potential of publication bias with funnel plots of the effect size by producing a Normal Quantile Plot37, we identified three data points (numbers 53, 54 and 55) with high residual values. These outliers were removed from the analyses. The final data set is based on 93 studies, which when represented by a funnel plot of sample and effect sizes, is approximately symmetrical (Fig. 2). For all four categories, the ratio of squared pooled variance (0.550) to mean study variance (0.057) is 9.584, which suggests that a test for homogeneity of effect size based on a random (or mixed) effects ANOVA is appropriate for these data38. Tests for homogeneity of effect size were based on Q statistics, with larger values indicating greater heterogeneity in effect sizes among comparisons. Total heterogeneity (QT) can be partitioned into within-group heterogeneity (QW) and between-group heterogeneity (QB), which is analogous to the partitioning of variance in an ANOVA with multiple factors.


The importance of spatial heterogeneity and self-restraint on mutualism stability - a quantitative review.

Wang RW, Dunn DW, Luo J, He JZ, Shi L - Sci Rep (2015)

Funnel plot of the effect size, split by host type: Woody plant (*), Insect (o), Herbaceous plant (∇), and Coral (×).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593180&req=5

f2: Funnel plot of the effect size, split by host type: Woody plant (*), Insect (o), Herbaceous plant (∇), and Coral (×).
Mentions: After examining the potential of publication bias with funnel plots of the effect size by producing a Normal Quantile Plot37, we identified three data points (numbers 53, 54 and 55) with high residual values. These outliers were removed from the analyses. The final data set is based on 93 studies, which when represented by a funnel plot of sample and effect sizes, is approximately symmetrical (Fig. 2). For all four categories, the ratio of squared pooled variance (0.550) to mean study variance (0.057) is 9.584, which suggests that a test for homogeneity of effect size based on a random (or mixed) effects ANOVA is appropriate for these data38. Tests for homogeneity of effect size were based on Q statistics, with larger values indicating greater heterogeneity in effect sizes among comparisons. Total heterogeneity (QT) can be partitioned into within-group heterogeneity (QW) and between-group heterogeneity (QB), which is analogous to the partitioning of variance in an ANOVA with multiple factors.

Bottom Line: However, when the data were split according to four categories of host: 1) cnidarian corals, 2) woody plants, 3) herbaceous plants, and 4) insects, a significantly positive effect in corals was revealed.The trends for the remaining three categories did not significantly differ to zero.Our results suggest that stability in mutualisms requires alternative processes, or mechanisms in addition to, spatial heterogeneity of hosts and/or 'self-restraint' of symbionts.

View Article: PubMed Central - PubMed

Affiliation: Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi'an, 710072, China.

ABSTRACT
Understanding the factors that enable mutualisms to evolve and to subsequently remain stable over time, is essential to fully understand patterns of global biodiversity and for evidence based conservation policy. Theoretically, spatial heterogeneity of mutualists, through increased likelihood of fidelity between cooperative partners in structured populations, and 'self-restraint' of symbionts, due to selection against high levels of virulence leading to short-term host overexploitation, will result in either a positive correlation between the reproductive success of both mutualists prior to the total exploitation of any host resource or no correlation after any host resource has been fully exploited. A quantitative review by meta-analysis on the results of 96 studies from 35 papers, showed no evidence of a significant fitness correlation between mutualists across a range of systems that captured much taxonomic diversity. However, when the data were split according to four categories of host: 1) cnidarian corals, 2) woody plants, 3) herbaceous plants, and 4) insects, a significantly positive effect in corals was revealed. The trends for the remaining three categories did not significantly differ to zero. Our results suggest that stability in mutualisms requires alternative processes, or mechanisms in addition to, spatial heterogeneity of hosts and/or 'self-restraint' of symbionts.

No MeSH data available.