Just saw this very cool paper in PLoS Biology on Wolbachia that appear to have converted from parasites to mutualists. Wolbachia are among my favorite organisms. They are intracellular bacteria that have been found to infect a wide diversity of invertebrate species. In many cases, the Wolbachia have male specific detrimental effects (I like to call the WMDs – Wolbachia of male destruction). In other cases (e.g., in filiarial nematodes), Wolbachia appear to be beneficial.
I had heard about the work in the new paper from one of the authors Michael Turelli, who was one of the main people to convince me to move to Davis. In this study, the authors returned to examine a population of Drosophila simulans that Turelli had studied some 20 years ago. In the previous studies Turelli and colleagues had found a “classic case” of Wolbachia infection spreading in nature. When they returned to study the population and did a suite of experiments, they found that the Wolbachia had acquired fecundity increasing mutations, making them mutualistic.
Though they have not yet figured out what mutations occurred, it seems that a little genome sequencing might help them. Just a little selfish plug there, since I led the first project to sequence a Wolbachia genome and would love to do some more …
For more information, see Weeks AR, Turelli M, Harcombe WR, Reynolds KT, Hoffmann AA (2007) From Parasite to Mutualist: Rapid Evolution of Wolbachia in Natural Populations of Drosophila. PLoS Biol 5(5): e114 doi:10.1371/journal.pbio.0050114.
Weeks, A., Turelli, M., Harcombe, W., Reynolds, K., & Hoffmann, A. (2007). From Parasite to Mutualist: Rapid Evolution of Wolbachia in Natural Populations of Drosophila PLoS Biology, 5 (5) DOI: 10.1371/journal.pbio.0050114
Wu, M., Sun, L., Vamathevan, J., Riegler, M., Deboy, R., Brownlie, J., McGraw, E., Martin, W., Esser, C., Ahmadinejad, N., Wiegand, C., Madupu, R., Beanan, M., Brinkac, L., Daugherty, S., Durkin, A., Kolonay, J., Nelson, W., Mohamoud, Y., Lee, P., Berry, K., Young, M., Utterback, T., Weidman, J., Nierman, W., Paulsen, I., Nelson, K., Tettelin, H., O’Neill, S., & Eisen, J. (2004). Phylogenomics of the Reproductive Parasite Wolbachia pipientis wMel: A Streamlined Genome Overrun by Mobile Genetic Elements PLoS Biology, 2 (3) DOI: 10.1371/journal.pbio.0020069