Five
Drosophila melanogaster strains showing high interspecific crossability with
D. simulans males, derived from the previous screening of a set of autosomal
plwB transposants, were selected and the effect of the
plwB insertion under the same genetic background (
white strain) on the interspecific crossability was examined. This phenotype was recessive in the two strains but semidominant in the other three strains. Trans-heterozygotes, however, showed high interspecific crossability compared with the parental homozygotes, suggesting some epistatic interactions between them. In three strains, the effect of the
plwB insertion region in different backgrounds (
w1118 strain) on the crossability was also tested. Homozygotes of a strain (#687) showed high interspecific crossability comparable to the
w background, while homozygotes of both #68 and #783 strains showed lower crossability than
w1118. Although #783 heterozygotes showed intermediate values between #783 homozygotes and
w1118, #68 heterozygotes showed a significantly higher insemination rate than
w1118 and the #68 homozygotes. These results suggest that the region around the
plwB insertion sites of #68 and #783 affects the interspecific crossability either positively or negatively depending on the genetic background. In all the stocks, positive correlation between interspecific crossability and the intraspecific mating speed was detected.
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