Choosiness will lead to the best offspring. Being too choosy, however, could in the end result in no offspring at all. Female fruit flies have a solution to this dilemma.
Across most animal species, females invest more resources into offspring production than males and thus prefer to mate with high-quality males that will sire high-quality offspring. However, this high choosiness can become problematic if high-quality males become rare, as females might be too choosy to mate with the available males and thus die without reproducing. How can females resolve this issue? Female fruit flies (Drosophila melanogaster, a widely used model organism for genetic studies) have the answer.
A study now shows that in fruit flies, virgin females select their first mating partner unselectively and then become choosier regarding male attractiveness after the first mating. This plasticity in choosiness allows females to reduce the risk of not reproducing by mating with the first male they encounter; high offspring quality is maintained as most eggs are fertilized by the last male a female mated with.
The mechanisms that regulate this shift in choosiness are linked to the release of a hormone after the first mating. This hormone directly binds to the female olfactory system and specifically desensitizes one class of olfactory neurons that detects a male pheromone. As a result of this post-mating desensitization, only males that produce large quantities of pheromones can activate these neurons and are accepted for mating by the female.
This research result has been published in Nature Ecology & Evolution on 21 June 2021.