Male Recombination in Dysgenic Hybrids of Drosophila Melanogaster: Chromosome Breakage or Mitotic Crossing-Over?

Abstract

Recombinant second chromosomes from dysgenic male hybrids of D. melanogaster have been made homozygous using a Curly balancer chromosome technique. Most of the chromosome homozygotes produced have apparently normal viability. The incidence of newly produced lethals, while as high as 5-10%, is not significantly higher than in non-recombinant chromosomes. Thus male recombination and mutation appear to occur independently of each other, rather than in the same gametes as would be expected if both were simultaneously produced by chromosome breakage and reunion. Furthermore, a summary of recombination clusters over a large series of experiments suggests that reciprocal and non-reciprocal clusters occur with approximately equal frequency. This is in agreement with predictions from a four-strand mitotic recombination model.