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Evolution of mutualism between globeflowers and their pollinating flies
Jean-Baptiste Ferdy1, Laurence Després, Bernard Godelle
1CC 63, Laboratoire Génome, populations, interactions, Université Montpellier II, F-34095, Montpellier, Cedex 05, France. ferdy@univ.montp2.fr
Journal of Theoretical Biology
|August 31, 2002
Summary
Plant-pollinator seed-eater mutualisms, like globeflower and globeflower flies, can evolve stable interactions. Flower shape influences fly oviposition strategies, potentially leading to reduced seed destruction and co-evolution.
Area of Science:
- Ecology
- Evolutionary Biology
- Theoretical Biology
Background:
- Plant-pollinator mutualisms where insects consume seeds while pollinating present complex ecological dynamics.
- The globeflower (Trollius europaeus) and its pollinating flies (Chiastocheta spp.) represent a unique system with multiple fly species coexisting and exhibiting varied oviposition behaviors.
Purpose of the Study:
- To investigate how globeflower morphology, specifically corolla shape, influences the evolution of oviposition strategies in its pollinating flies.
- To explore the potential for co-evolution and the establishment of stable mutualistic relationships.
Main Methods:
- An adaptive dynamics model was developed to simulate the evolutionary interactions between globeflower traits and fly oviposition behaviors.
- Key traits examined included flower age at oviposition, clutch size, avoidance of parasitized flowers, and corolla shape (closed vs. open).
Main Results:
- Evolutionary branching was observed, leading to divergence in fly oviposition timing (early vs. late) due to larval competition.
- A closed corolla shape was found to protect early-ovipositing fly eggs, increasing larval competition and selecting for smaller clutch sizes in these flies.
- A closed corolla shape was positively selected for in globeflowers, reducing overall parasitism and promoting stable mutualism.
Conclusions:
- Flower morphology, particularly a closed corolla, can drive the evolution of mutualistic behaviors in seed-pollinator interactions.
- The findings support the hypothesis of sympatric speciation in flies within their host plant and suggest a pathway to stable plant-pollinator mutualism.