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Predictable patterns of trait mismatches between interacting plants and insects.

Anderson B, Terblanche JS, Ellis AG - BMC Evol. Biol. (2010)

Bottom Line: This result held at the population level, as well as for phylogenetically adjusted analyses at the species-level and for both pollination and host-parasite interactions, perhaps suggesting a general pattern.Similarly, plant mating system also affected the degree of trait correspondence because selfing reduces the reliance on pollinators and is analogous to pollination generalization.Our analyses suggest that there are predictable "winners" and "losers" of evolutionary arms races and the results of this study highlight the fact that breeding system and the degree of specialization can influence the outcome.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Animal Interactions, Botany and Zoology Department, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa. banderso.bruce@gmail.com

ABSTRACT

Background: There are few predictions about the directionality or extent of morphological trait (mis)matches between interacting organisms. We review and analyse studies on morphological trait complementarity (e.g. floral tube length versus insect mouthpart length) at the population and species level.

Results: Plants have consistently more exaggerated morphological traits than insects at high trait magnitudes and in some cases less exaggerated traits than insects at smaller trait magnitudes. This result held at the population level, as well as for phylogenetically adjusted analyses at the species-level and for both pollination and host-parasite interactions, perhaps suggesting a general pattern. Across communities, the degree of trait mismatch between one specialist plant and its more generalized pollinator was related to the level of pollinator specialization at each site; the observed pattern supports the "life-dinner principle" of selection acting more strongly on species with more at stake in the interaction. Similarly, plant mating system also affected the degree of trait correspondence because selfing reduces the reliance on pollinators and is analogous to pollination generalization.

Conclusions: Our analyses suggest that there are predictable "winners" and "losers" of evolutionary arms races and the results of this study highlight the fact that breeding system and the degree of specialization can influence the outcome.

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Related in: MedlinePlus

Plant-insect trait-matching at the population level. Scatter plot showing population means for insect and plant morphological traits from all the studies in Table 1 (excluding autonomous selfing plants). Solid line: slope of unity (intercept assumed to be the same as the value derived from the RMA regression intercept: 3.61); Stippled line: RMA derived slope through all data (slope: 0.851 ± 0.026; t90 = 5.7242, p < 0.0001).
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Figure 2: Plant-insect trait-matching at the population level. Scatter plot showing population means for insect and plant morphological traits from all the studies in Table 1 (excluding autonomous selfing plants). Solid line: slope of unity (intercept assumed to be the same as the value derived from the RMA regression intercept: 3.61); Stippled line: RMA derived slope through all data (slope: 0.851 ± 0.026; t90 = 5.7242, p < 0.0001).

Mentions: Using OLS, eleven out of twelve relationships had significant positive slopes for plant versus insect traits suggesting close trait matching. Both of the parasitic relationships had slopes which were statistically shallower than one (Table 1). Using RMA, of the ten pollination relationships, eight of them were for plants which were pollinator-dependent and all of these had slopes which were <1 (3/8 significantly so, Table 1). Both antagonistic and mutualistic pollination relationships of non-selfing species consistently had slopes of less than one. In contrast, both of the autonomous selfing pollination relationships had slopes which were >1, but not statistically so (β = 1.278 ± 0.325, t6 = -0.856, p = 0.788 and β = 1.417 ± 0.518, t3 = -0.806, p > 0.2396). Furthermore if all slopes are analyzed together (mean β = 0.7729 ± 0.31916 (SD)) against an expected slope of one using a one sample t-test, then this analysis also suggests that slopes are significantly shallower than one (t11 = 8.3910, p < 0.00001). Excluding autonomous selfers (which probably have putatively relaxed selective pressures on floral traits, see discussion) from this analysis only serves to reinforce the pattern of the slope being less than one (mean β = 0.6581 ± 0.1880 (SD), t9 = 11.0670, p < 0.00001). Similar results were obtained if the axes were reversed (results not shown) or if the slopes were analysed using ordinary least-squares (OLS) regression (Additional file 1). If the data from all population studies are combined as a single RMA regression (excluding autonomous selfers), the slope (β = 0.8514 ± 0.0280) of the relationship is significantly shallower than one (t90 = 5.724, P < 0.0001, Tabe 1, Figure 2). If only antagonistic/parasitic species are grouped together, the RMA slope of the relationship is significantly less than one (β = 0.8104 ± 0.053, t29 = 3.5720, p < 0.001), and when all mutualistic (non-selfing) species are grouped together, (β = 0.8625 ± 0.028, t59 = 4.9585, p < 0.00001). Thus, in general, whether analyzing populations within species (Table 1) or pooling populations across species (Figure 2), imbalances in trait matching with respect to trait magnitude appear to be common and consistent, favouring the plants most when trait magnitudes are large.


Predictable patterns of trait mismatches between interacting plants and insects.

Anderson B, Terblanche JS, Ellis AG - BMC Evol. Biol. (2010)

Plant-insect trait-matching at the population level. Scatter plot showing population means for insect and plant morphological traits from all the studies in Table 1 (excluding autonomous selfing plants). Solid line: slope of unity (intercept assumed to be the same as the value derived from the RMA regression intercept: 3.61); Stippled line: RMA derived slope through all data (slope: 0.851 ± 0.026; t90 = 5.7242, p < 0.0001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927919&req=5

Figure 2: Plant-insect trait-matching at the population level. Scatter plot showing population means for insect and plant morphological traits from all the studies in Table 1 (excluding autonomous selfing plants). Solid line: slope of unity (intercept assumed to be the same as the value derived from the RMA regression intercept: 3.61); Stippled line: RMA derived slope through all data (slope: 0.851 ± 0.026; t90 = 5.7242, p < 0.0001).
Mentions: Using OLS, eleven out of twelve relationships had significant positive slopes for plant versus insect traits suggesting close trait matching. Both of the parasitic relationships had slopes which were statistically shallower than one (Table 1). Using RMA, of the ten pollination relationships, eight of them were for plants which were pollinator-dependent and all of these had slopes which were <1 (3/8 significantly so, Table 1). Both antagonistic and mutualistic pollination relationships of non-selfing species consistently had slopes of less than one. In contrast, both of the autonomous selfing pollination relationships had slopes which were >1, but not statistically so (β = 1.278 ± 0.325, t6 = -0.856, p = 0.788 and β = 1.417 ± 0.518, t3 = -0.806, p > 0.2396). Furthermore if all slopes are analyzed together (mean β = 0.7729 ± 0.31916 (SD)) against an expected slope of one using a one sample t-test, then this analysis also suggests that slopes are significantly shallower than one (t11 = 8.3910, p < 0.00001). Excluding autonomous selfers (which probably have putatively relaxed selective pressures on floral traits, see discussion) from this analysis only serves to reinforce the pattern of the slope being less than one (mean β = 0.6581 ± 0.1880 (SD), t9 = 11.0670, p < 0.00001). Similar results were obtained if the axes were reversed (results not shown) or if the slopes were analysed using ordinary least-squares (OLS) regression (Additional file 1). If the data from all population studies are combined as a single RMA regression (excluding autonomous selfers), the slope (β = 0.8514 ± 0.0280) of the relationship is significantly shallower than one (t90 = 5.724, P < 0.0001, Tabe 1, Figure 2). If only antagonistic/parasitic species are grouped together, the RMA slope of the relationship is significantly less than one (β = 0.8104 ± 0.053, t29 = 3.5720, p < 0.001), and when all mutualistic (non-selfing) species are grouped together, (β = 0.8625 ± 0.028, t59 = 4.9585, p < 0.00001). Thus, in general, whether analyzing populations within species (Table 1) or pooling populations across species (Figure 2), imbalances in trait matching with respect to trait magnitude appear to be common and consistent, favouring the plants most when trait magnitudes are large.

Bottom Line: This result held at the population level, as well as for phylogenetically adjusted analyses at the species-level and for both pollination and host-parasite interactions, perhaps suggesting a general pattern.Similarly, plant mating system also affected the degree of trait correspondence because selfing reduces the reliance on pollinators and is analogous to pollination generalization.Our analyses suggest that there are predictable "winners" and "losers" of evolutionary arms races and the results of this study highlight the fact that breeding system and the degree of specialization can influence the outcome.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Animal Interactions, Botany and Zoology Department, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa. banderso.bruce@gmail.com

ABSTRACT

Background: There are few predictions about the directionality or extent of morphological trait (mis)matches between interacting organisms. We review and analyse studies on morphological trait complementarity (e.g. floral tube length versus insect mouthpart length) at the population and species level.

Results: Plants have consistently more exaggerated morphological traits than insects at high trait magnitudes and in some cases less exaggerated traits than insects at smaller trait magnitudes. This result held at the population level, as well as for phylogenetically adjusted analyses at the species-level and for both pollination and host-parasite interactions, perhaps suggesting a general pattern. Across communities, the degree of trait mismatch between one specialist plant and its more generalized pollinator was related to the level of pollinator specialization at each site; the observed pattern supports the "life-dinner principle" of selection acting more strongly on species with more at stake in the interaction. Similarly, plant mating system also affected the degree of trait correspondence because selfing reduces the reliance on pollinators and is analogous to pollination generalization.

Conclusions: Our analyses suggest that there are predictable "winners" and "losers" of evolutionary arms races and the results of this study highlight the fact that breeding system and the degree of specialization can influence the outcome.

Show MeSH
Related in: MedlinePlus