Reading #5

Increase in toxicity of an invasive weed after reassociation with its coevolved herbivore

Zangerl and Berenbaum, PNAS 102: 15529-15532

Reading Questions:

1. What hypothesis do the authors set out to test? What novel approach do they use?

2. What are the important defensive compounds of the wild parsnip?

3. How do the authors know that these phytochemicals are stable in herbarium specimens for hundreds of years? What evidence is shown or discussed to show this?

4. How is the presence of parsnip webworm, rather than other herbivorous insects demonstrated, on old herbarium specimens?

5. What, if anything, do you conclude about the metabolic cost of secondary plant metabolites based on this study?

6. (bonus). Have you ever been to a herbarium? Where is the closest one?