PT  - JOURNAL ARTICLE
AU  - Anupama Prakash
AU  - Antónia Monteiro
TI  - &lt;em&gt;Doublesex&lt;/em&gt; mediates the development of sex-specific pheromone organs in &lt;em&gt;Bicyclus&lt;/em&gt; butterflies via multiple mechanisms
AID  - 10.1101/686477
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 686477
4099  - http://biorxiv.org/content/early/2019/06/28/686477.short
4100  - http://biorxiv.org/content/early/2019/06/28/686477.full
AB  - The Bicyclus lineage of satyrid butterflies exhibits male-specific traits, the scent organ complex, used for chemical communication during courtship. This complex consists of tightly packed brush-like scales (hair-pencils) that rub against scent patches to disperse pheromones, but the evolution and molecular basis of the organ’s male-limited development remains unknown. Here, we examine the evolution of the number and location of the scent patches and hair-pencils within 53 species of Bicyclus butterflies, and the involvement of the sex determinant gene doublesex (dsx) in scent organ development in Bicyclus anynana using CRISPR/Cas9. We show that scent patches and hair-pencils arose via multiple, independent gains, in a correlated manner. Further, an initially non-sex-specific Dsx protein expression pattern in developing wing discs becomes male-specific and spatially refined to areas that develop the scent organ complex over the course of development. Functional perturbations of dsx show that this gene is required for male patch development whereas hair-pencils can develop in both sexes without Dsx input. Dsx in females is, instead, required to repress hair-pencils. These findings suggest that the patches and hair-pencils evolve as correlated composite organs that are sex-limited via the spatial regulation of dsx. Divergence in the function of dsx isoforms occurs in both sexes, where the male isoform promotes patch development in males and the female isoform represses hair-pencil development in females, both leading to the development of male-limited traits. Furthermore, evolution in number and location of patches, but not of hair-pencils, appears to be regulated by spatial regulation of dsx.