Biosciences Graduate Program

Stephen D. Hendrix, BS, PhD


Professor of Biology

Contact Information

Office: 425 BB
Iowa City, IA 52242
Phone: 319-335-065

Web: More About Dr. Hendrix - Related Websites and Resources


BS, Biology, Florida State University
PhD, Botany, University of California-Berkeley

Research Summary

Conservation Biology of Populations The broad research interests in our laboratory center around conservation biology of populations and communities, both plants and insects (herbivores and pollinators) native to prairies. We are concentrating on the effects of habitat fragmentation on the ecology of prairie forbs (non-grass-like flowering plants) and their associated pollinators and herbivores because they are an excellent model system to study fragmentation and because they constitute the bulk of species biodiversity on prairies. Our studies of the species richness of the butterfly community in prairie fragments and preserves show that reductions in plant population size associated with fragmentation can decrease the attractiveness of small populations to pollinators and that as a result, reproduction is decreased, particularly for obligately outcrossing plants. This conclusion is supported by long-term studies of the arrival of pollen to flowers in many populations. We also have evidence that loss of genetic variation in small populations is affecting fitness of offspring in some prairie forbs. Presently, we are analyzing relationships between the richness and abundance of floral rewards in prairie remnants as well as the surrounding landscape and the richness and abundance of pollinators. In this multi-year study we are examining wild bee and butterfly diversity at preserves and railroad remnants in collaboration with Dr. Diane Debinski at Iowa State University. In addition to community level studies of the effects of habitat fragmentation on pollinator abundance, we are also examining how communities of herbivores respond to fragmentation of prairies. Our studies of the herbivores associated with one prairie forb, Amorpha canescens (leadplant), reveal a loss of herbivores in small populations, but abundances of herbivores is infrequently related to population size. These herbivores may be functioning as metapopulations and are an excellent system in which to test important aspects of theoretical models of metapopulation dynamics. For example, we have quantified patterns of dispersal of three specialist phytophagous beetles across the fragmented prairie landscape using mark-recapture methods. Our results indicate that recent history of host plant abundance in response to fragmentation may be as important as dispersal characteristics in determining spatial population structure of these remnant dependent insects. Lastly, our laboratory is also involved in practical studies examining the effects of whitetail deer herbivory on deciduous forest understory plants. This work is designed to determine levels of impact of deer on species richness of forbs and on spatial distribution of vegetation in order for local governmental agencies to make deer management decisions on the basis of sound scientific data.

Date Last Modified: 06/06/2016 - 13:17:48