Sexual roles exchanged by some mites 40 million years ago

2011/05/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Biologia
• Eboluzioa
• Paleontologia
• Arkeologia

They are found in the amber of the Baltic: mite male and female copulando. Researchers from the University of Michigan and the Russian Academy of Sciences have studied the fossil and found that they belong to a species currently missing, Glaesacarus rhombeus. They calculate that they are 40 million years old and have realized their particularity: they had interchange of sexual roles with respect to the current ones.

In fact, among most of the current species of mites, during fertilization, males dominate females. The males fight each other to get a female and, once achieved, they try to have no relation with another. In addition, the males have special organs to stick and hold the female during the copula.

However, the mite male trapped in amber lacks organ. The female, for its part, has in the background a kind of cushion, by which the researchers conclude that it dominated the male.

However, the females of some current species also have structures for the control of males, since some female mites have a copulation tube with penile function. Therefore, they were special but not unique.