Female Mosquitofish Can Regulate Who They Wish To Mate With

The female mosquitofish can alter her genitals to keep unwanted males from mating with her.

Male Mosquito fish (Gambusia affinis. Via NOZO/Wikipedia

In the human world, no means no, or at least it should. In the fish world, the female mosquitofish have been able to develop different sized and shaped genital openings when predators are nearby, and, get this, when they want to block male mosquitofish from different populations from trying to mate with them.

Female mosquitofish can alter the size and shape of their genitals to keep certain males from mating with them. Photo by C. Anderson

“Genital openings are much smaller in females that live with the threat of predators and are larger and more oval shaped in females living without the threat of predation,” said Brian Langerhans, assistant professor of biological sciences at North Carolina State University and the corresponding author of a paper published in the journal Evolution that describes the research.

“Our lab previously showed that male mosquitofish have more bony and elongated genitalia when living among predators. When predators lurk nearby, male fish must attempt to copulate more frequently – and more hurriedly – with females. So females have evolved a way to make copulation more difficult for unwanted males.”

This evolutionary aspect of the female mosquitofish is what the researchers call the lock and key theory whereby certain males that the females don’t want to copulate with are unable to because the female essentially has different genitalia that the unwanted male cannot penetrate. This avoids such things as “hybridization with maladapted populations or other species.” The scientists say that the genitalia of the female mosquitofish evolves to reduce hybridization.

Article Categories:
Fish · Freshwater Fish