PIG: The jigsaw experiment

Cornell’s Plant-Insect Group, affectionately known as PIG, has been meeting for weekly discussions every semester for at least 12 years.  In the old days, Paul Feeny and Dick Root would join us for inspiring discussions, merging the past with the future.  These days, the Ithaca group, digitally connected with folks in Geneva, NY, is frequently a gaggle of over 30 attending students, faculty, postdocs, and staff. This semester we are trying the jigsaw experiment with the first few weeks of the semester.

In each session we pick a single important topic in PIG research.  The topic of the first session was the interaction between herbivory and pollination.  We were divided into 5 groups, with each group reading only of the one of the following articles.  Each group prepared a single slide with some history, the key results, and conceptual issues of the paper. Synthesis comes from putting the pieces together: if the jigsaw works well, each groups has questions for others, and holes in knowledge get filled.  OK, it wasn’t a totally transformative experience on our first try, but, we’re working on it!

One thing that stuck out to me was how diverse the approaches were … from studying multiple populations of a single species in space and time with a focus on the fitness effects of herbivory and pollination (Herrera et al.), to the effects of herbivory on the plasticmphenotype and attractiveness of plants (Strauss et al).  Roles for nectar chemistry were studied using a genetically modified species (Kessler et al.) to tens of closely related species in a phylogenetic framework (Adler et al.). Many pollinators are themselves herbivores (or at least their offspring are), and Kephart et al. reviewed cases of pollinating seed parasites less extreme than yuccas and figs.

Flowers are more important for pollinators in outcrossing species, they seem to be subject to the spectrum of poor to good pollination across the board, and nectar chemistry mediates diverse interactions, from positive to negative.  We still don’t have resolution as for the extent to which nectar chemistry is passively linked to shoot chemistry, with the plant evolving around this constraint – vs. a more adaptive distribution of compounds in the plant.  Do we have a theory of herbivore-pollinator interactions?  I don’t think so, but perhaps we don’t need one.  These interactions appear common, they are sometimes adaptive, and they occur by diverse mechanisms. Some herbivore-pollinator interactions are predictable by the plant’s reproductive mode.  We await other generalities or predictions about when and where interactions between pollinators and herbivores are most important.

Next week: growth –defense trade-offs


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