Hybrid dysgenesis: Evolution of different I‐R properties in related strains of Drosophila melanogaster

Abstract

In crosses between females from a reactive strain and males from an inducer strain the daughters, designated SF females, are sterile because of a reduced hatching rate of the eggs. In the reciprocal cross the daughters. RSF females, have normal fertility. In intrastrain crosses and crosses involving neutral strains no sterility effects appear. The genome from a moderately reactive strain with long generation intervals was introduced into six different maternal inducer strains by backcrosses for at least 19 generations, 16 lines divided into six groups of two to four parallel lines were kept with short generation intervals. Two lines from different groups were inducer while all others were strongly reactive. Three parallel lines with long generation intervals were reactive but on different levels. Three parallel lines started from RSF females and reactive males and kept with short intervals for 10 generations of endogamous matings were classified as neutral. In order to get some information about the population dynamics of the I‐R system five strains with a common origin and kept apart for 80–100 generations were tested. The results showed that evolutionary processes had occurred. Two strains were inducer, one was reactive and two were classified as neutral. Copyright © 1985, Wiley Blackwell. All rights reserved