PREZYGOTIC ISOLATION BETWEEN SACCHAROMYCES CEREVISIAE AND SACCHAROMYCES PARADOXUS THROUGH DIFFERENCES IN MATING SPEED AND GERMINATION TIMING
Article first published online: 23 DEC 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 66, Issue 4, pages 1196–1209, April 2012
How to Cite
Murphy, H. A. and Zeyl, C. W. (2012), PREZYGOTIC ISOLATION BETWEEN SACCHAROMYCES CEREVISIAE AND SACCHAROMYCES PARADOXUS THROUGH DIFFERENCES IN MATING SPEED AND GERMINATION TIMING. Evolution, 66: 1196–1209. doi: 10.1111/j.1558-5646.2011.01516.x
- Issue published online: 6 APR 2012
- Article first published online: 23 DEC 2011
- Accepted manuscript online: 22 NOV 2011 12:36AM EST
- Received September 10, 2009, Accepted November 4, 2011, Data Archived: Dryad doi:10.5061/dryad.708bb5kr
- Allochronic isolation;
- mating speed;
- reproductive isolation;
- spore germination;
- wild yeast
Although prezygotic isolation between sympatric populations of closely related animal and plant species is well documented, far less is known about such evolutionary phenomena in sexual microbial species, as most are difficult to culture and manipulate. Using the molecular and genetic tools available for the unicellular fungus Saccharomyces cerevisiae, and applying them to S. paradoxus, we tested the behavior of individual cells from sympatric woodland populations of both species for evidence of prezygotic isolation. First, we confirmed previous observations that vegetative cells of both species mate preferentially with S. cerevisiae. Next, we found evidence for mate discrimination in spores, the stage in which outcrossing opportunities are most likely to occur. There were significant differences in germination timing between the species: under the same conditions, S. paradoxus spores do not begin germinating until almost all S. cerevisiae spores have finished. When germination time was staggered, neither species discriminated against the other, suggesting that germination timing is responsible for the observed mate discrimination. Our results indicate that the mechanisms of allochronic isolation that are well known in plants and animals can also operate in sexual microbes.