biostudies-literatureUnknownOuadah YNIDA NIH HHSWe have identified a <i>Drosophila</i> species which exhibits spontaneous and robust intermale sexual behavior. <i>D. santomea</i> males distinguish conspecific sexes but court both vigorously and seldom attack. Elevated intermale courtship stems from at least three evolutionarily derived pheromonal changes. In males, the sexually monomorphic cuticular pheromone 7-tricosene promotes rather than inhibits courtship and the courtship-inhibiting olfactory pheromone cVA is reduced 84-92% compared to close relatives. The third switch is in <i>D. santomea</i> females, where cVA suppresses rather than promotes sexual receptivity. Female cVA aversion and male cVA reduction may have co-evolved to maintain efficient intraspecific mating but prevent hybridization with the sympatric sibling species D<ibioRxiv : the preprint server for biology2025.10.14.682417https://www.ebi.ac.uk/biostudies/studies/S-EPMC12632756biostudies-literatureEvolutionary basis of intermale sexual behavior by multiple pheromone switches in &lt;i&gt;Drosophila&lt;/i&gt;.PMC12632756R37 DA031389Smihula HNaragon THOuadah YBehrman ELDing YParker JAnderson DJKhallaf MAStern DLfalseEvolutionary basis of intermale sexual behavior by multiple pheromone switches in &lt;i&gt;Drosophila&lt;/i&gt;.We have identified a <i>Drosophila</i> species which exhibits spontaneous and robust intermale sexual behavior. <i>D. santomea</i> males distinguish conspecific sexes but court both vigorously and seldom attack. Elevated intermale courtship stems from at least three evolutionarily derived pheromonal changes. In males, the sexually monomorphic cuticular pheromone 7-tricosene promotes rather than inhibits courtship and the courtship-inhibiting olfactory pheromone cVA is reduced 84-92% compared to close relatives. The third switch is in <i>D. santomea</i> females, where cVA suppresses rather than promotes sexual receptivity. Female cVA aversion and male cVA reduction may have co-evolved to maintain efficient intraspecific mating but prevent hybridization with the sympatric sibling species D<i2025-01-01T00:00:00Z2025 Nov2026-06-12T03:16:28.07Z2026-06-12T03:07:55.464ZS-EPMC126327564127946110.1101/2025.10.14.682417