Tim Karr recently moved from the University of Chicago to the Department of Biology and Biochemistry at the University of Bath (new email T.L.Karr@bath.ac.uk).

Tim is interested in the evolution of sperm-egg interactions in Drosophila, particularly the role that sperm length variation plays in generating reproductive isolation. A related area of investigation involves mechanistic studies by which an endocellular symbiont, Wolbachia, causes reproductive failure in Drosophila.

Tim and Bill collaborated in a study that was published in 1996. We keep planning to contine our scientific collaboration, particually on warm summer afternoon's or cold winter eveinings.

Ballard JWO, Hatzidakis J, Karr TL, Kreitman M. 1996. Reduced variation in Drosophila simulans mitochondrial DNA. Genetics 144: 1519-1528.

We investigated the evolutionary dynamics of infection of a Drosophila simulans population by a maternally inherited insect bacterial parasite, Wolbachia, by analyzing nucleotide variability in three regions of the mitochondrial genome in four infected and 35 uninfected lines. Mitochondrial variability is significantly reduced compared to a noncoding region of a nuclear-encoded gene in both uninfected and pooled samples of flies, indicating a sweep of genetic variation. The selective sweep of mitochondrial DNA may have been generated by the fixation of an advantageous mitochondrial gene mutation in the mitochondrial genome. Alternatively, the dramatic reduction in mitochondrial diversity may be related to Wolbachia.

Tim Karr: T.L.Karr@bath.ac.uk