Insects and Plants 3/7/2012. Coevolution. Coevolution. Reciprocal evolution

Transcription

1 and Plants Butterflies and Plants: a study in coevolution By Ehrlich & Raven A classic! Coevolution Reciprocal evolution The hawk moth (Xanthopan morganii) visiting the Madagascar Star Orchid (Angraecum sesquipedale) (Illustration by Emily Damstra for the Smithsonian Institution) Coevolution Reciprocal evolution Evolutionary arms race Diana Marques 1

2 How do plants and insect interact? 1. Phytophagy (herbivory) 2. Pollination and other behaviors affecting plant reproduction 3. Mutualisms involving insects residing in plants Coevolution Reciprocal evolution Evolutionary arms race Feeding Guilds How to exploit the plant? Galls Chewing Sucking Mining Boring Galling Gall Formers The species of insect that created the gall can often be determined by the shape and size of the gall. Spiked pea galls on rose ~ 13,000 insect species (20 families, 7 orders) are known to induce galls. Gall formers alter the development of the plant tissue to form a tumor-like growth, in which the insect gains nutrition and protection from the environment. Spangle Galls on oak Robin's pincushion gall on wild rose 2

3 Galls Galls can develop on any plant part (leaf, stem, root, fruit, flower). Plant defenses All organisms are potentially food for others. Plants don t passively let themselves get eaten! How do they defend themselves? Goldenrod plant with Goldenrod Gall Fly, Eurosta solidaginis Defense e.g. Trichomes 3

4 Phaseolus vulgaris Common bean Defense defenses usually keep herbivores away But, sometimes they attract specialist herbivores! Milkweed beetle Tetraopes tetrophthalmus (Coleoptera: Cerambycidae) Milkweed has cardiac glycosides that monarch butterflies are able to sequester and use to defend themselves Taxol from Pacific Yew, Taxus brevifolia Defense Alkaloids Cardiac glycosides (heart poisons) Tannins Cyanide Terpenoids Lots more Taxol was isolated from bark of Pacific Yew in 1970s. Taxol interferes with cell division by binding to the protein tubulin, a key factor in mitosis. Taxol and related compounds now widely used in treating breast and ovarian cancer. Reference Futuyma 1983 Taxol, a terpenoid. 4

5 vs. Defenses defense - always present defense - synthesized in response to challenge Defense : Talking Plants Wild tobacco and sagebrush Communication using methyl jasmonate How do plants and insect interact? 1. Phytophagy (herbivory) 2. Pollination and other behaviors affecting plant reproduction 3. Mutualisms involving insects residing in plants R. Karban, I.T. Baldwin, K.J. Baxter, G. Laue, G.W. Felton. Oecologia 2000 Pollination and seed dispersal Myrmecochory seed dispersal by ants Elaiosomes NCSU 5

6 How do plants and insect interact? 1. Phytophagy (herbivory) 2. Pollination and other behaviors affecting plant reproduction 3. Mutualisms involving insects residing in plants Plant Rewards to Helpers This is yet another way that plants can defend themselves Food Bodies Domatia Extra Floral Nectaries How can you tell if a plant structure is a domatia or a gall? Acacia have tannins, spines, and ants Dr. Todd Palmer s lab in the Biology Department Acacia drepanolobium Tanzania and Kenya 6

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