Anonim

Animals born of parthenogenesis may be fertile. Not only: this reproductive strategy is more common than one might think, so much so that it represents, for some species, a real alternative to sexual reproduction.

For the first time, a female shark born "without dad" has been observed giving life to offspring with virginal reproduction (virgin birth, that is without the help of a male). A discovery that shakes the conviction that individuals born by parthenogenesis were to be considered a "dead branch" of evolution, destined to perish earlier than others and without reproductive possibilities.

Without father, without husband. The double reproduction without fertilization was observed on a female white-spotted bamboo shark (Chiloscyllium plagiosum) kept in captivity. Genetic analysis had established that his offspring was born without a father, with the development of embryos autonomously - through a sort of autoclonation of the maternal DNA - from egg cells not fertilized by a male.

One of the daughters gave birth in turn to parthenogenesis, showing that this type of reproduction is not an error of evolution, as is often believed. The research was conducted by Nicolas Straube of the Bavarian State Collection for Zoology in Munich (Germany).

Not so rare. A second study published almost simultaneously shows that parthenogenesis is widespread in 20 different species of snakes. So far it has occasionally been observed in the rattlesnakes (a subfamily of venomous vipers), in sharks, in sawfish (even in the wild and not only in captivity) and in some birds, but it was thought to be a rare expedient. The two new discoveries change the cards on the table.