A multilocus study of an experimental barley population

Abstract

Morphological marker loci and enzyme loci were studied in the experimental barley population Composite Cross II. This population was started in 1929 by crossing 28 varieties of barley and pooling equal numbers of the F2 seed. Subsequently, the population has been grown at Davis, Calif., without conscious selection. Large directional changes occurred in allelic frequencies for four of the five enzyme loci studied. A decline in genie diversity occurred at all the morphological marker loci, and three of these loci became monomorphic after 45 generations. The esterase loci were significantly associated with each other, but other loci did not form as significant associations. Multilocus associations fluctuated in intensity over generations, being weaker in the intermediate generations studied than in the early or late generations. These patterns must be largely due to natural selection, but whether selection acts directly on these loci cannot be resolved. Copyright © 1982, Wiley Blackwell. All rights reserved