Abstract
One Sentence Summary We identify one nucleotide substitution in a gene regulatory region contributing to evolutionary change of two distinct copulatory organs.
We identify a gene and 3 substitutions causing genital evolution between species
The evolved mutations lie in a pleiotropic enhancer
One mutation decreases genital bristle number and increases leg sex comb tooth number
This mutation disrupts a binding site for Abd-B in genitals and for another factor in legs
SUMMARY Diverse traits often covary between species. The possibility that a single mutation could contribute to the evolution of several characters between species is rarely investigated as relatively few cases are dissected at the nucleotide level. Drosophila santomea has evolved additional sex comb sensory teeth on its legs and has lost two sensory bristles on its genitalia. We found that a single nucleotide substitution in an enhancer of the scute gene contributes to both changes. The mutation alters a binding site for the Hox protein Abdominal-B in the developing genitalia, leading to bristle loss, and for another factor in the developing leg, leading to bristle gain. Our study shows that morphological evolution between species can occur through a single nucleotide change affecting several sexually dimorphic traits.
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