'Armed race' in the genital organs of ducks

An interesting ' race ' in the evolution of the genitalia in male and female ducks has just been discovered by scientists. This study eliminates the notion that female creatures are always passive members in the relationship between two varieties.

Evolution to dominate competition

Up to 97% of poultry species have no parts that function similarly to human penis. Ducks are species in the remaining 3%, there is a penis to maintain the race.

In non-penile birds, they mate in the way that biologists call 'touch through cloacal kiss', ie quick contact through a hole in both males. and the - this hole has both a secretory function and a means to release eggs and sperm.

The genitals of male and female ducks have evolved together to overcome each other in a form of ' arms race ' to gain birth control. (Photo: Richard-seaman)

Unlike many other poultry species, male ducks have penises that vary in length, depending on the species, from just about 1.27 cm short to 38 cm! Moreover, their penis is also very diverse in appearance, from smooth to thorny and grooved.

Scientists reason that male duck penis has evolved to become longer to dominate the competition in bringing female duck's egg to sperm faster and more likely to conceive.

Patricia Brennan, an expert on behavioral ecology of two universities: Yale in the US and Sheffield in the UK, said: 'After studying the genitalia of male ducks, I was immediately attracted to the idea. think how the female reproductive part of the duck must be constructed to hold the male duck's bizarre penis.

Brennan and her colleagues unexpectedly found that the female duck's pussy was also "picky" no less than the male duck's penis. Their pussy is full of dead ends and other coping tools, and these structures seem to be designed to remove the penis from the mating they don't like.

Like locks and keys

In most poultry species, the vulva or the ovary is just a simple tube, however, in some ducks, the vulva has bags on either side of the vaginal wall. These bags are fake "dead ends " or "entrances" for the penis.

Brennan explained: 'If the penis enters these bags, they are blocked, unable to reach the egg nozzle to release sperm'.

The female duck's eggshell also contains many cramped structures with a clockwise twist. In this regard, the ornithologist Richard Prum, partner of Mrs. Brenna, said: 'It is interesting, because the male duck's penis is also spiral-shaped, but in the opposite direction . counterclockwise, counterclockwise. . Therefore, the pussy and penis in the duck are like a set of locks and keys. '

The team investigated 14 different species of ducks and geese. The results showed that over time evolution, the number of vesicles and twisted structures in the reproductive organs of female ducks increased while the male duck's penis also grew longer.

Brennan said: 'I was able to predict how the male genitalia's structure should be compatible with the female reproductive apparatus, and vice versa.'

This study shows that the genitals of both male and female ducks have evolved to remedy each other in a form of 'arms race' to gain birth control.

Depending on the species, the duck's penis is very different in length, from just about 1.27 cm short to 38 cm long!(Photo: LiveScience)

Prum said: "Although most ducks follow the 'monogamous' regime, the 'forced' children by males are common in many ducks. organisms are strongly related to the frequency of forced intercourse in that species " .

Therefore, according to Ms Brennan: 'In order to react to the' rape 'of male ducks, female ducks are able to use their own physical and behavioral conditions to decide which male duck can be paternalism'.

That means that the male duck's penis has evolved in order to overcome the increasingly subtle self-protection of the female duck's genital organ, and vice versa, the reproductive apparatus of the female duck even progresses. more to counteract the " attack " of male ducks.

She said: 'Some birds have large bodies and live in a' monogamous' regime, such as geese and swans, have a small penis, while others have small bodies and live long lives. If you are pregnant, you have a large and complex genital organ. '

Active selection mechanism of female organisms

Evolutionary cases as detected in ducks are part of the interaction in the reproductive process of all animals, including humans.(Photo: Richard-seaman)

According to the team, when the female duck is satisfied with the " flirt " with the male, it will show a cooperative attitude by facilitating the male's penis to overcome its own protective barrier. out. If the female is determined not to accept the male, it will not let the penis get out of the vagina.

Robert Montgomerie, an evolutionary biology expert at Queen's University in Kingston, Canada, commented: 'These findings help eliminate the notion that female creatures are always passive members of the term. relationship between 2 varieties'.

According to him, this study helps us always remember that we must have equal interest for both sexes in the reproductive process. Meanwhile, the learner, Kevin Johnson, believes that research should be extended to other animals to detect similar evolutionary cases.

As for her research, Brennan said: 'What really interests me is the secret mechanism of the children's choice. Imagine an evolutionary environment in which males have a longer penis, while females create more barriers in the genitals to protect themselves. That is an 'arms race' about evolution '.

'We think that such evolutionary cases are spreading and are part of the interaction in the reproductive process of all animals, including humans.'

This study was published in PloS One (Public Library of Science) on May 2, 2007.

Minh Quang