FITNESS RECOVERY AND COMPENSATORY EVOLUTION IN NATURAL MUTANT LINES OF C. ELEGANS
Article first published online: 11 APR 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 8, pages 2335–2344, August 2011
How to Cite
Estes, S., Phillips, P. C. and Denver, D. R. (2011), FITNESS RECOVERY AND COMPENSATORY EVOLUTION IN NATURAL MUTANT LINES OF C. ELEGANS. Evolution, 65: 2335–2344. doi: 10.1111/j.1558-5646.2011.01276.x
- Issue published online: 26 JUL 2011
- Article first published online: 11 APR 2011
- Accepted manuscript online: 7 MAR 2011 11:22AM EST
- Received August 27, 2010, Accepted February 14, 2011
- experimental evolution;
- mutation accumulation;
Deleterious mutation accumulation plays a central role in evolutionary genetics, conservation biology, human health, and evolutionary medicine (e.g., methods of viral attenuation for live vaccines). It is therefore important to understand whether and how quickly populations with accumulated deleterious mutational loads can recover fitness through adaptive evolution. We used laboratory experimental evolution with four long-term mutation–accumulation (MA) lines of Caenorhabditis elegans nematodes to study the dynamics of such fitness evolution. We previously showed that when homozygous mutant populations are evolved in large population sizes, they can rapidly achieve wild-type fitness through the accumulation of new beneficial or compensatory epistatic mutations. Here, we expand this approach to demonstrate that when replicate lineages are initiated from the same mutant genotype, phenotypic evolution is only sometimes repeatable. MA genotypes that recovered ancestral fitness in the previous experiment did not always do so here. Further, the pattern of adaptive evolution in independently evolved replicates was contingent upon the MA genotype and varied among fitness-related traits. Our findings suggest that new beneficial mutations can drive rapid fitness evolution, but that the adaptive process is rendered somewhat unpredictable by its susceptibility to chance events and sensitivity to the evolutionary history of the starting population.