Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1996

Asher D. Cutter
Tufts University
Medford, Massachusetts
Conrad C. Labandeira, Ph.D.
Supervising Scientist
Department of Paleobiology
"The extensive facilities and resources of the Smithsonian are exceeded in quality and value only by the care, dedication, and genuine concern by the scientists and staff for my educational development."

Evaluation of Insect Herbivory of the Flora from the Middle Eocene Green River Formation (48Ma) in Eastern Utah

ABSTRACT
Plants and insects have likely interacted since the early stages of insect evolution, and the complexity and variety of their interactions is suspected to have increased to the current high level of diversity through time in response to escalation. While considerable study has dealt with the diversity of plant-insect interactions of modern ecosystems, little research has focused on data from fossil records. Therefore, understanding of pre-modern plant-insect interactions and the mechanism by which the diversity of present-day interactions came about is limited. By evaluating fossil floras for herbivory and classifying the herbivory according to insect functional feeding groups, a non-taxon dependent categorization based on insect mouthpart morphology and feeding behavior, as well as quantitatively describing the herbivory exhibited in fossil plants according to the intensity and extent of damage comparisons, may be made between various temporally distinct fossil and modern floras. This project evaluates the Middle Eocene Green River flora by assessing the percentage of damaged leaf area removed by insect herbivores (herbivory intensity), proportion of damaged leaves (extent of herbivory), and type of damage (functional feeding groups), and compares it with Early Permian and Late Cretaceous floras. Herbivory in the Eocene flora is described, quantitatively evaluated, and the partitioning of leaf damage according to functional feeding groups is compared between this Eocene flora and a Cretaceous flora. The data support neither the ecological saturation hypothesis nor the expanding resources hypothesis with regard to the evolution of aspects of ecological function over time. Similarly, escalation of plant-insect interactions in the context of herbivory is not supported by these fossil records. Given the present paucity of estimates of ancient plant-insect interactions, especially herbivory, it is evident that a more complete evaluation of such interactions should be made through geologic time for selected, environmentally determined vegetation communities for hypotheses regarding evolution to be adequately tested.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9531331.

Letter of Gratitude