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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

Hypothetical outcomes of trait-matching studies. Figure 1A. Geographic variability in the strengths of directional selection may weaken a regression (i.e. increase variability) by increasing the frequency and magnitude of trait mismatches (where a trait mismatch is indicated by a double headed arrow). However, this may not affect the slope of the relationship which indicates the predictability of the direction of the trait mismatches in relation to trait magnitude. Figure 1B. The slope of the trait regression relationship may reveal one of three possible scenarios: Slope 1, where insect and plant traits are not matched, slope 2, where trait matching scales with trait magnitude to produce a slope of 1 and slopes 3a and b where there is a consistent and predictable mismatch of traits where the mismatch is contingent on trait magnitude. For example, in slope 3a the plants have predictably longer traits than the insects and the mismatch between the taxa should become greater with trait magnitude.
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Figure 1: Hypothetical outcomes of trait-matching studies. Figure 1A. Geographic variability in the strengths of directional selection may weaken a regression (i.e. increase variability) by increasing the frequency and magnitude of trait mismatches (where a trait mismatch is indicated by a double headed arrow). However, this may not affect the slope of the relationship which indicates the predictability of the direction of the trait mismatches in relation to trait magnitude. Figure 1B. The slope of the trait regression relationship may reveal one of three possible scenarios: Slope 1, where insect and plant traits are not matched, slope 2, where trait matching scales with trait magnitude to produce a slope of 1 and slopes 3a and b where there is a consistent and predictable mismatch of traits where the mismatch is contingent on trait magnitude. For example, in slope 3a the plants have predictably longer traits than the insects and the mismatch between the taxa should become greater with trait magnitude.

Mentions: Therefore, one possible, though perhaps simplistic expectation from these interactions is perfect matching between the morphological traits of interacting species pairs, but in reality mismatches are commonplace. For example, even Darwin's famous hawkmoth, which is frequently cited as textbook example of close trait-matching [e.g. [19]], has a proboscis which is considerably shorter than the nectar spur of Angraecum sesquipedale. In addition, Nilsson [3] observed that several studies report corolla tubes which were longer than the tongues of their pollinators. Although trait mismatches may seem counter-intuitive, the geographic mosaic theory of coevolution predicts that they should be common [20-22]. One potential reason for trait mismatches is that geographic differences in community structure can alter the strength of selection imposed by one species upon another, and vice versa, resulting in putatively balanced armaments in some populations but imbalanced armaments in others. Although geographic variation in the strength of directional selection may result in trait mismatches, which might weaken the correlation between co-varying traits across populations, this mechanism need not result in predictable mismatches in a particular direction across coevolving species pairs (Figure 1A). Trait mismatches in a geographic mosaic need not influence the form of the relationship between interacting phenotypes, an important component of trait matching which is less frequently reported and less well-understood than the significance of the relationship itself.


Predictable patterns of trait mismatches between interacting plants and insects.

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

Hypothetical outcomes of trait-matching studies. Figure 1A. Geographic variability in the strengths of directional selection may weaken a regression (i.e. increase variability) by increasing the frequency and magnitude of trait mismatches (where a trait mismatch is indicated by a double headed arrow). However, this may not affect the slope of the relationship which indicates the predictability of the direction of the trait mismatches in relation to trait magnitude. Figure 1B. The slope of the trait regression relationship may reveal one of three possible scenarios: Slope 1, where insect and plant traits are not matched, slope 2, where trait matching scales with trait magnitude to produce a slope of 1 and slopes 3a and b where there is a consistent and predictable mismatch of traits where the mismatch is contingent on trait magnitude. For example, in slope 3a the plants have predictably longer traits than the insects and the mismatch between the taxa should become greater with trait magnitude.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Hypothetical outcomes of trait-matching studies. Figure 1A. Geographic variability in the strengths of directional selection may weaken a regression (i.e. increase variability) by increasing the frequency and magnitude of trait mismatches (where a trait mismatch is indicated by a double headed arrow). However, this may not affect the slope of the relationship which indicates the predictability of the direction of the trait mismatches in relation to trait magnitude. Figure 1B. The slope of the trait regression relationship may reveal one of three possible scenarios: Slope 1, where insect and plant traits are not matched, slope 2, where trait matching scales with trait magnitude to produce a slope of 1 and slopes 3a and b where there is a consistent and predictable mismatch of traits where the mismatch is contingent on trait magnitude. For example, in slope 3a the plants have predictably longer traits than the insects and the mismatch between the taxa should become greater with trait magnitude.
Mentions: Therefore, one possible, though perhaps simplistic expectation from these interactions is perfect matching between the morphological traits of interacting species pairs, but in reality mismatches are commonplace. For example, even Darwin's famous hawkmoth, which is frequently cited as textbook example of close trait-matching [e.g. [19]], has a proboscis which is considerably shorter than the nectar spur of Angraecum sesquipedale. In addition, Nilsson [3] observed that several studies report corolla tubes which were longer than the tongues of their pollinators. Although trait mismatches may seem counter-intuitive, the geographic mosaic theory of coevolution predicts that they should be common [20-22]. One potential reason for trait mismatches is that geographic differences in community structure can alter the strength of selection imposed by one species upon another, and vice versa, resulting in putatively balanced armaments in some populations but imbalanced armaments in others. Although geographic variation in the strength of directional selection may result in trait mismatches, which might weaken the correlation between co-varying traits across populations, this mechanism need not result in predictable mismatches in a particular direction across coevolving species pairs (Figure 1A). Trait mismatches in a geographic mosaic need not influence the form of the relationship between interacting phenotypes, an important component of trait matching which is less frequently reported and less well-understood than the significance of the relationship itself.

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