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Cycads: their evolution, toxins, herbivores and insect pollinators
Dietrich Schneider1, Michael Wink, Frank Sporer
1Max-Planck-Institut, Seewiesen/Starnberg, Germany.
Die Naturwissenschaften
|September 10, 2002
Summary
Ancient cycads and insects may have formed mutualistic relationships before flowering plants evolved. Modern cycad pollinators and herbivores can sequester plant toxins, suggesting early co-evolutionary interactions.
Area of Science:
- Paleobiology
- Evolutionary Biology
- Botany
Background:
- Gymnosperms, like cycads, were wind-pollinated, while insect pollination emerged with angiosperms in the Lower Cretaceous.
- Cycads, primitive seed-plants, were abundant during the Mesozoic era.
- Modern cycads show pollination by beetles and thrips, suggesting ancient insect-plant interactions.
Purpose of the Study:
- To explore the possibility of early mutualistic interactions between insects and cycads in the Triassic period.
- To investigate the role of plant defensive compounds in insect-cycad relationships.
- To analyze toxin uptake and storage in cycad pollinators and herbivores.
Main Methods:
- Palaeobiological evidence review.
- Analysis of modern cycad pollination systems (beetles, thrips).
- Investigation of toxin sequestration in specific insect species (weevil, butterfly).
Main Results:
- Speculation of Triassic-era insect-cycad mutualism predating angiosperms.
- Identification of toxic azoglucosides and amino acids in cycads as key interaction factors.
- New data on cycasin uptake and storage by the pollinator *Rhopalotria mollis* and herbivore *Eumaeus atala*.
Conclusions:
- Insect-cycad interactions, including pollination and herbivory, are influenced by plant toxins.
- The study provides evidence for the sequestration of cycad toxins by associated insects.
- Ancient mutualistic relationships between cycads and insects are plausible, driven by co-evolutionary processes.