Courtship behavior: Resurrecting an undead song.

Area of Science:

• Evolutionary genetics
• Neurobiology
• Animal behavior

Background:

• The fruit fly Drosophila melanogaster uses a complex courtship song for mating.
• Courtship song production involves specific neurons in the ventral nerve cord.
• The sex-determining gene doublesex (dsx) plays a crucial role in sexual differentiation in flies.

Purpose of the Study:

• To investigate the genetic and developmental basis for the loss of an ancestral courtship song component in Drosophila yakuba.
• To understand the role of the dsx gene in the ontogenetic death of neurons in D. yakuba males.

Main Methods:

• Comparative genomics analysis of dsx gene in D. yakuba and D. melanogaster.
• Histological examination of ventral nerve cord development in D. yakuba.
• Analysis of dsx isoform function in cell culture or transgenic models.

Main Results:

• Drosophila yakuba males exhibit ontogenetic death of specific courtship song effector neurons.
• The D. yakuba dsx gene produces a male isoform (dsxM) with potent cell-death-promoting activity.
• This dsxM activity is similar to the cell-death-promoting activity of the female isoform (dsxF) in D. melanogaster, leading to neuron loss in males.

Conclusions:

• The loss of an ancestral courtship song component in D. yakuba is caused by programmed cell death of essential neurons.
• The sex-determining gene dsx in D. yakuba has evolved a male-specific function that induces neuronal apoptosis.
• This represents a significant evolutionary divergence in the regulation of sexual behavior and neural development between closely related fly species.