Previously unobservable events occurring between insemination and fertilization are the subject of a groundbreaking new article in Science magazine…By genetically altering fruit flies so that the heads of their sperm were fluorescent green or red, John Belote and his colleagues were able to observe in striking detail what happens to live sperm inside the female. The findings may have huge implications for the fields of reproductive biology, sexual selection and speciation.
According to Scott Pitnick, many advances in reproductive and evolutionary biology have been constrained by the inability to discriminate competing sperm of different males and by the challenges of observing live sperm inside the female reproductive tract. The solution? Glow-in-the-dark sperm. “Our first goal with these flies was to tackle the mechanisms underlying sperm competition,” says Pitnick. “Whenever a female mates with more than one male—and female promiscuity is more the rule than the exception in nature—there are conflicts between the sexes over paternity, as well as competition between rival ejaculates to fertilize eggs. Such postcopulatory sexual selection is a powerful force for evolutionary change…”
Pitnick says his team has created similar glowing sperm populations for other species, including ones that hybridize, so he can observe what happens when sperm and the female are evolutionarily mismatched. “I suspect we have just scratched the surface of using this material,” he says.
It boggles the mind. Might also fit into our never-ending quest for entertainment.