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. Author manuscript; available in PMC: 2010 Jun 17.
Published in final edited form as: Trends Genet. 2008 May 29;24(7):317–319. doi: 10.1016/j.tig.2008.04.003

Figure 1.

Figure 1

Genetic causes of abdominal pigmentation evolution. The two closely related species, Drosophila yakuba and Drosophila santomea, shown schematically at the top, display different levels of abdominal pigmentation. This difference results from changes in at least four quantitative trait loci (QTLs) that all occurred on the lineage leading to D. santomea [9]. Two QTLs reside on the X chromosome (QTL X1 and QTL X2), one on chromosome II (QTL 2) and one on chromosome III (QTL 3). The order of evolved QTLs is shown for illustration purposes only. The true order of QTL evolution is unknown. Jeong et al. [8] investigated the genetic changes underlying QTL X2. They found that changes in an abdomen-specific cis-regulatory element of the tan gene, shown below, had evolved in D. santomea. They identified three classes of alleles carrying different mutations that all incapacitate the cis-regulatory element. The cis-regulatory enhancer sequences are represented as horizontal lines at the bottom. Point mutations that alter function are shown as asterisks above the D. santomea sequences. Deletions are shown as gaps in the sequence.