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Size matters. Bigger genitals mean more mating success for male mosquito fish, a relative of the guppy. But the development of longer male organs prompts females to evolve bigger brains to help them escape overeager mates.
Mating among mosquito fish is far from romantic. The male makes no effort to court partners, instead sneaking up and attempting to copulate by force up to a thousand times a day. It uses a modified anal fin, the gonopodium, to deliver sperm into the female.
In this sort of mating system, the relationship between males and females can resemble that between predators and prey, which commonly involve an evolutionary arms race where adaptations on one side are closely matched by changes on the other. For example, big-brained predators tend to prey on big-brained prey, as the two try to outsmart each other.
Séverine Buechel and colleagues at Stockholm University in Sweden wondered if a similar arms race was going on between male and female mosquito fish. Do females evolve bigger brains to defend against sneaky males, and do males evolve bigger brains in response?
To test this, the team looked at what happened to brain size when males were bred to have longer gonopodia. Male mosquito fish have long gonopodia compared with related species in which coercion is not the dominant mating strategy, and males with longer gonopodia tend to be more successful at mating.
The researchers found that breeding more well-endowed males led to bigger-brained females. But there was no arms race: male brains didn’t get bigger at the same time.
Read more here. (New Scientist)
Mating among mosquito fish is far from romantic. The male makes no effort to court partners, instead sneaking up and attempting to copulate by force up to a thousand times a day. It uses a modified anal fin, the gonopodium, to deliver sperm into the female.
In this sort of mating system, the relationship between males and females can resemble that between predators and prey, which commonly involve an evolutionary arms race where adaptations on one side are closely matched by changes on the other. For example, big-brained predators tend to prey on big-brained prey, as the two try to outsmart each other.
Séverine Buechel and colleagues at Stockholm University in Sweden wondered if a similar arms race was going on between male and female mosquito fish. Do females evolve bigger brains to defend against sneaky males, and do males evolve bigger brains in response?
To test this, the team looked at what happened to brain size when males were bred to have longer gonopodia. Male mosquito fish have long gonopodia compared with related species in which coercion is not the dominant mating strategy, and males with longer gonopodia tend to be more successful at mating.
The researchers found that breeding more well-endowed males led to bigger-brained females. But there was no arms race: male brains didn’t get bigger at the same time.
Read more here. (New Scientist)
