View Program - 63rd Annual Drosophila Research Conference

In polyandrous internally fertilizing species, a multiply-mated female can exert preference on which stored sperm she uses to fertilize her eggs. The female’s ability to assess sperm quality and compatibility is essential for her reproductive success, and represents an important aspect of postcopulatory sexual selection. In Drosophila melanogaster, previous studies demonstrated that the female nervous system plays an active role in influencing progeny paternity proportion, and suggested a role for octopaminergic/tyraminergic Tdc2 neurons in this process. Here, we report that inhibiting Tdc2 neuronal activity causes females to produce a higher-than-normal proportion of first-male progeny. This difference is not due to differences in sperm storage or release, but attributable to the suppression of preference for second-male sperm that normally occurs in control females. We further show that a subset of Tdc2 neurons innervating the female reproductive tract was largely responsible for the progeny proportion phenotype that was observed when Tdc2 neurons were inhibited globally. On the contrary, over-activation of Tdc2 neurons does not further affect sperm storage and release or progeny proportion. These results suggest that octopaminergic/tyraminergic signaling allows a multiply-mated female to exert sperm preference, and identify a new role for the female nervous system in postcopulatory sexual selection.

Octopaminergic/tyraminergic Tdc2 neurons regulate sperm preference in female Drosophila melanogaster