Comparison of b chromosome effects on secale cereale and secale vavilovii

Abstract

B chromosomes of S. cereale have been introduced into S. vavilovii, which lacks them in nature, to compare their effects on fitness. In both species, viability was unaffected, while fertility progressively decreased when the number of B chromosomes increased from two to four. These effects depend on the B chromosome number of the individuals, and not on the frequency of B chromosomes in the population. From the similarity of B chromosome effects on S. cereale and S. vavilovii it is argued that the maintenance of B chromosome polymorphisms mainly depends on B chromosomes themselves, and not on a coadaptation between B chromosomes and the cereale genome. © 1985 The Genetical Society of Great Britain.