Genetic reagents target homologous neurons in multiple Drosophila species
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Homologous descending neurons drive distinct fly songs in a similar social context
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Evolutionary changes downstream of the homologous neurons cause song differences
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Courtship song circuit multifunctionality may facilitate rapid fly song evolution
Summary
It is unclear where in the nervous system evolutionary changes tend to occur. To localize the source of neural evolution that has generated divergent behaviors, we developed a new approach to label and functionally manipulate homologous neurons across Drosophila species. We examined homologous descending neurons that drive courtship song in two species that sing divergent song types and localized relevant evolutionary changes in circuit function downstream of the intrinsic physiology of these descending neurons. This evolutionary change causes different species to produce divergent motor patterns in similar social contexts. Artificial stimulation of these descending neurons drives multiple song types, suggesting that multifunctional properties of song circuits may facilitate rapid evolution of song types.