Heterochromatin readjusting chiasma distribution in two species of the genus arcyptera: The effect among individuals and populations

Abstract

Chiasma variation has been studied in two selected chromosomes from two species of the genus Arcyptera according to the heterochromatin distribution per bivalent. The differences in chiasma distribution found between each karyomorph revealed an underlying tendency for chiasmata to occupy characteristic positions in the bivalents depending on the heterochromatin distribution. It seems that the heterozygosity of the bivalent more than the presence of heterochromatic segments is readjusting a standard pattern of chiasma distribution. The findings of this survey are discussed in relation to the significance and role of genetical recombination in natural populations depending on the frequency of karyomorphs per populations and the pattern of chiasma distribution per individual. © 1986 The Genetical Society of Great Britain.