Julie Koester
When is a new species born? The ocean appears to be a well mixed habitat, yet new, cryptic species of phytoplankton are identified each year. I am interested in how populations of organisms in the ocean differentiate from one another such that they are reproductively isolated. I am currently investigating the role that polyploidy plays in speciation of diatoms and the opportunities that polyploidy provides for gene differentiation. Polyploid species tend to have larger cell sizes than their diploid relatives, therefore altering the physiology of each cell. Ultimately, I would like to tie genetic differences back to observable physiological differences between sister species with different genome sizes.
Left to right 1-3: 1) Two gametic valves and one large valve from a sexual clone of Ditylum brightwellii from the Gulf of Maine, 2-3) Ditylum brightwellii: a large clone from Puget Sound and small clone from New Zealand.
Publications
- Koester, J.A., Brawley, S.H.B., Karp-Boss, L. and Mann, D. 2007. Sexual reproduction in the marine centric diatom Ditylum brightwellii (Bacillariophyta). European Journal of Phycology. 42(4):351-366