A study on Heliconius butterflies reveals that visual preferences for red patterns in two species, H. melpomene and H. timareta, evolved through adaptive introgression, where genetic material was exchanged via hybridization. The gene regucalcin1, which is involved in neural expression and courtship behavior, plays a key role in this process. Researchers found that regucalcin1 expression is linked to visual preference across populations, and disrupting it with CRISPR/Cas9 impairs courtship behavior. The study highlights how hybridization contributes to behavioral evolution and shows how visually guided behaviors, important for adaptation and speciation, are encoded in the genome. The findings suggest that regucalcin1 is a critical gene for visual preference, and its expression differences are cis-regulated, meaning they are controlled by regulatory elements within the gene itself. The study also shows that regucalcin1 knockout in H. melpomene leads to reduced courtship behavior, indicating its specific role in male mating behavior. Overall, the research demonstrates the importance of hybridization in generating genetic variation that can be selected for in behavioral evolution.A study on Heliconius butterflies reveals that visual preferences for red patterns in two species, H. melpomene and H. timareta, evolved through adaptive introgression, where genetic material was exchanged via hybridization. The gene regucalcin1, which is involved in neural expression and courtship behavior, plays a key role in this process. Researchers found that regucalcin1 expression is linked to visual preference across populations, and disrupting it with CRISPR/Cas9 impairs courtship behavior. The study highlights how hybridization contributes to behavioral evolution and shows how visually guided behaviors, important for adaptation and speciation, are encoded in the genome. The findings suggest that regucalcin1 is a critical gene for visual preference, and its expression differences are cis-regulated, meaning they are controlled by regulatory elements within the gene itself. The study also shows that regucalcin1 knockout in H. melpomene leads to reduced courtship behavior, indicating its specific role in male mating behavior. Overall, the research demonstrates the importance of hybridization in generating genetic variation that can be selected for in behavioral evolution.