Divergent phenotypic plasticity of a convergent Mendelian trait in Drosophila

Abstract

In Drosophila, comparisons of the thermal plasticity of pigmentation across serially homologous abdominal segments have been conducted in two species, namely Drosophila melanogaster and D. kikkawai. Pigmentation variation has different genetic architecture in the two species, being oligogenic in the former and monogenic in the later. Here, we analyze the thermal plasticity of abdominal pigmentation in a third species, D. erecta, which is phylogenetically close to D. melanogaster but like D. kikkawai has a monogenic basis for pigmentation variation. However, the underlying locus differs between D. erecta and D. kikkawai, being the X-linked melanin-synthesis gene tan in the former and the autosomal transcription factor pdm3 in the later. We found that in spite of a low overall plasticity in monogenic species compared to D. melanogaster, the two monogenic species showed divergent plasticity patterns in respect to the response to temperature and to the degree of dominance in heterozygotes. Those results provide new insights on the dependence of the degree of plasticity on the genetic architecture as well as on the extent of phenotypic convergence.