Abstract
AbstractDirect observation is central to our understanding of the process of adaptation, but evolution is rarely documented in a large, multicellular organism for more than a few generations. Here, we observe genetic and phenotypic evolution across a century-scale competition experiment, barley composite cross II (CCII). CCII was founded in 1929 with tens of thousands of unique genotypes and has been adapted to local conditions in Davis, CA, USA for 58 generations. We find that natural selection has massively reduced genetic diversity leading to a single clonal lineage constituting most of the population by generation F50. Selection favored alleles originating from similar climates to that of Davis, and targeted genes regulating reproductive development, including some of the most well-characterized barley diversification loci,Vrs1,HvCEN, andPpd-H1. We chronicle the dynamic evolution of reproductive timing in the population and uncover how parallel molecular pathways are targeted by stabilizing selection to optimize this trait. Our findings point to selection as the predominant force shaping genomic variation in one of the world’s oldest ongoing biological experiments.One-Sentence SummaryWholesale genetic restructuring of an experimental population is a consequence of rapid environmental adaptation.
Publisher
Cold Spring Harbor Laboratory
Reference65 articles.
1. H. V. Harlan , M. L. Martini , A Composite Hybrid Mixture. Agron. J. 21, 487 (1929).
2. D. Zohary , M. Hopf , E. Weiss , Domestication of Plants in the Old World: The Origin and Spread of Domesticated Plants in Southwest Asia, Europe, and the Mediterranean Basin ( OUP Oxford, 2012).
3. R. W. Allard , A. L. Kahler , “Patterns of molecular variation in plant populations” in Proceedings of the Sixth Berkeley Symposium on Mathematical Statistics and Probability, Volume 5: Darwinian, Neo-Darwinian, and non-Darwinian Evolution (The Regents of the University of California, 1972; http://projecteuclid.org/euclid.bsmsp/1200514600).
4. Genetic evidence for a second domestication of barley (Hordeum vulgare) east of the Fertile Crescent
5. Targeted resequencing reveals genomic signatures of barley domestication;New Phytol,2018