The dominance effect of the adaptive transposable element insertion Bari-Jheh depends on the genetic background

Although adaptive mutations are often considered to be dominant, it has been recently shown that a substantial proportion of adaptive mutations should display heterozygote advantage. In this work, we take advantage of a recently characterized transposable element insertion mediating oxidative stress response in Drosophila melanogaster to test the dominance effect of an adaptive mutation. The comparison of the survival curves of heterozygous and the two corresponding homozygous flies indicated that the dominance effect of Bari-Jheh depends on the genetic background. Both in homozygous and in heterozygous flies, Bari-Jheh was associated with upregulation of Jheh1 (Juvenile Hormone Epoxyde Hydrolase 1) and/or Jheh2 genes. Our results add to the limited number of studies in which the dominance effect of adaptive mutations has been empirically estimated and highlights the complexity of their inheritance.