Artificial selection on the sex ratio in Drosophila pseudoobscura

Open Access
Publisher Website
Google Scholar
Abstract
Experiments were undertaken to detect genetic variation for the sex ratio in D. pseudoobscura that is independent of the “sex-ratio” (SR) meiotic drive system. Females inseminated in a natural population produce broods that are heterogeneous with respect to sex ratio. Lines selected for high percentage of male progeny responded in one of two independent artificial selection experiments; the realized heritability was 0.101. Interline crosses between the selected high (percent males) line, low line, and an unselected standard stock reveal a significant male effect, nonsignificant female effect, and marginally significant interaction. Selection gains were rapidly lost when selection was relaxed. Males carrying the SR X-chromosome on a genetic background selected for high percentage of males show no modification of SR meiotic drive. It is suggested that populations are polymorphic for autosomal or X-linked variants that modify the segregation of sex chromosomes and are maintained in a polymorphic state by a balance between segregation and zygotic selection.