Evolutionary Ecology of Mycophagous Drosophila

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Drosophila have played a central role in the study of genetics, development, and evolution. Dr. Jaenike's research focuses on mushroom feeding species of Drosophila which are ideally suited to studies of the ecology and behavior of these insects. A primary concern of the proposed research will be with ecological interactions between these Drosophila and a species of nematode that parasitizes them. Because as many as 50% of these flies are parasitized at any time and because infected flies are seriously debilitated in terms of fertility, these nematodes have a substantial impact on populations of Drosophila. A series of field and laboratory studies will be used to investigate how nematodes affect survival, mating success, and competitive interactions of their Drosophila hosts. How ecological factors, such as ambient temperature, mushroom species, and Drosophila population densities, affect frequencies of parasites will also be examined. This research will provide basic information on the ecology of host-parasite interactions. In additions, because nematodes have the potential to be important agents for biological control of insects, this work could shed light on how best to carry out such control programs. Dr. Jaenike also has plans to study chromosomes which he has discovered to affect sex ratio in a species of Drosophila. Because "sex ratio" males sire only daughters, these chromosomes are expected in theory to increase in frequency and eventually cause population extinction. In reality, they do not do so. Dr. Jaenike will study ecological factors, including competitive ability and susceptibility to nematode parasitism, that may prevent the spread of these chromosomes. This research will provide insight on how selection at one level (chromosomes within individuals) is counteracted by selection at another level (individuals within populations).