EVOLUTIONARY RESCUE OF SEXUAL AND ASEXUAL POPULATIONS IN A DETERIORATING ENVIRONMENT
Article first published online: 11 JUN 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 11, pages 3508–3518, November 2012
How to Cite
Lachapelle, J. and Bell, G. (2012), EVOLUTIONARY RESCUE OF SEXUAL AND ASEXUAL POPULATIONS IN A DETERIORATING ENVIRONMENT. Evolution, 66: 3508–3518. doi: 10.1111/j.1558-5646.2012.01697.x
- Issue published online: 25 OCT 2012
- Article first published online: 11 JUN 2012
- Accepted manuscript online: 20 MAY 2012 09:31PM EST
- Received March 29, 2012 Accepted May 8, 2012 Data Archived: doi:10.5061/dryad.6df73
- experimental evolution;
- genetic variation;
- salt stress
The environmental change experienced by many contemporary populations of organisms poses a serious risk to their survival. From the theory of evolutionary rescue, we predict that the combination of sex and genetic diversity should increase the probability of survival by increasing variation and thereby the probability of generating a type that can tolerate the stressful environment. We tested this prediction by comparing experimental populations of Chlamydomonas reinhardtii that differ in sexuality and in the initial amount of genetic diversity. The lines were serially propagated in an environment where the level of stress caused by salt increased over time from fresh water to the limits of marine conditions. In the long term, the combination of high diversity and obligate sexuality was most effective in supporting evolutionary rescue. Most of the adaptation to high-salt environments in the obligate sexual-high diversity lines had occurred by midway through the experiment, indicating that positive genetic correlations of adaptation to lethal stress with adaptation to sublethal stress greatly increased the probability of evolutionary rescue. The evolutionary rescue events observed in this study provide evidence that major shifts in ways of life can arise within short time frames through the action of natural selection in sexual populations.