The evolution of Bab paralog expression and abdominal pigmentation among Sophophora fruit fly species. Issue 6 (November 2013)

• Record Type: Journal Article
• Authors: Salomone, Joseph R.; Rogers, William A.; Rebeiz, Mark; Williams, Thomas M.
• Is Part Of: Evolution & development. Volume 15:Issue 6(2013)
• Page Start: 442
• Page End: 457
• Publication Date: 2013-11
• Subjects: Evolution (Biology) -- Periodicals; Developmental biology -- Periodicals; 576.82
• DOI: 10.1111/ede.12053
• Languages: English
• ISSNs: 1520-541X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>SUMMARY</title> <sec id="ede12053-sec-0001" sec-type="section"> <p>The evolution of gene networks lies at the heart of understanding trait divergence. Intrinsic to development is the dimension of time: a network must be altered during the correct phase of development to generate the appropriate phenotype. One model of developmental network evolution is the origination of dimorphic (male‐specific) abdomen pigmentation in the fruit fly subgenus <italic>Sophophora</italic>. In <italic>Drosophila</italic> (<italic>D</italic>.) <italic>melanogaster</italic>, dimorphic pigmentation is controlled by the dimorphic expression of the paralogous Bab1 and Bab2 transcription factors that repress pigmentation. These expression patterns are thought to have evolved from a monomorphic ancestral state. Here we show that the spatial domain and contrast in dimorphic Bab expression increases during the latter half of pupal development, and this late pupal expression is necessary and sufficient to suppress pigmentation. Late pupal Bab expression was monomorphic for species from basal clades exhibiting monomorphic pigmentation, though dimorphic expression was observed in <italic>D. pseudoobscura</italic> that represents an intermediate‐branching monomorphic clade. Among species from the dimorphic <italic>Sophophora</italic> clades, Bab expression was dimorphic, but a poor correlation was found between the domains of expression and male pigmentation. Lastly, while Bab paralog co‐expression was generally observed, an instance of paralog‐specific expression was found, indicating more complex regulatory mechanisms and mutational effects have shaped the evolution of the <italic>bab</italic> locus. These results highlight the importance of the time and place of Bab expression for pigmentation development and evolution, and suggest that dimorphism evolved early in <italic>Sophophora</italic>, but diversity in male pigmentation was not further shaped by alterations in Bab expression.</p> </sec> </abstract>