r e s e a r c h.. p r o g r a m . o v e r v i e w

We are interested in solving problems in ecological and evolutionary genetics. We use a system that involves Drosophila that rely on decaying plant tissue for larval and adult nutrition. The drosophilids feed on the decaying tissue as well as the microorganisms (mainly yeasts) that are involved in the decay process. The yeasts depend on the drosophilds for transportation to new host plants, so that the system (Host Plant-Yeast-Drosophila) is suitable for studying coevolution. Studies on Drosophila have focused on population genetics, molecular evolution and ecological genetics. Our interest in the plant is centered around the chemistry of the tissue and its influence on the development of the yeasts and drosophilids. In general the evolution of the plant characteristics such as chemical deterrents is tracked by the saprophytes (drosophilids and yeasts) and not caused by them.

Investigations on the yeasts have included taxonomic descriptions, systematics, physiology, genetics and community ecology. Our studies on the community ecology of the yeasts incorporate several potentially important determinant factors such as 1) the host-specific dispersal of the drosophilids, 2) the presence of toxic host chemicals; chemicals that would prevent occupation by the yeasts, 3) competitive interference by yeasts in the form of 'Killer toxins' that inhibit and kill other yeasts attempting to colonize a habitat and 4) benefits (nutritional and otherwise) to the vector that is needed to get to the next host-plant. We have found all of these factors to be important in determining the yeast community membership. Systems that we have studied include host tissues of cactus (stems or fruits), mushrooms, flowers (morning glory in Hawaii and Hibiscus in Australia), and other fruit habitats such as citrus and wild grapes.

Collaborative studies on ancient microorganisms entrapped in glacial ice from Greenland and Antarctica are being conducted with three other groups (Scott Rogers and John Castello, ESF-SUNY; Jack Fell, U. of Miami). We are interested in isolating live organisms that have been frozen since they were deposited over time from snow fall at both poles. We have thus far been successful in obtaining viruses, bacteria and fungi from ice that is from 100s to 100,000s of years old. Live cultures have been obtained and PCR-methods have been successfully used to detect ancient microbes.

Undergraduate students: Please click here for information about research opportunities in my lab.