Discovered in Portugal fish that steals eggs to clone himself


This is the first case of natural androgenesis in vertebrates and was discovered by Portuguese in the Ocreza River, in the Serra da Gardunha. This fish steals the eggs of the females and manages to clone itself through them. What remains for researchers is to find out how it does it.

It was scientists at the University of Lisbon who discovered a fish that steals eggs from females in order to be able to clone through a process called androgenesis. This is the first time that a case of androgenesis (a process in which a new living being develops exclusively from the genetic material of the progenitor male) is detected in nature among vertebrates. This fish, of the species Squalius alburnoides (the common name is bordalo), was found in the river Ocreza, that is born in the Mountain of the Gardunha and it empties in the river Tagus. This study was published in the Royal Society Open Science.

Androgenesis is a rare phenomenon of asexual reproduction, this process has already been achieved in a laboratory environment, but has never been observed among vertebrates spontaneously in nature. According to the explanations given by the scientists in their report, “the male of this fish produces sperm whose sex cells contain twice the normal genetic material. Then the male steals the eggs of female fish, which for some reason does not contain parent genetic material, and deposits the sperm inside. The egg develops and gives rise to a fish that is genetically equal to the parent”.

However, this explanation raises other questions, the point is that scientists do not know why eggs do not have the genetic material of the female inside. They believe the male can destroy him. There is also the hypothesis that this is a case of a “natural accident” in which the egg developed without genetic information and the fish, as a parasite, took advantage of it to clone. None of these theories has been confirmed by the scientific community, but it is certain that this case, being isolated or somewhat recurrent in the reproductive life of Squalius alburnoides, is “the first empirical proof of spontaneous androgenesis occurring naturally among vertebrates”. To date, this form of reproduction has only been identified in mollusks and arthropods.

All the results were obtained when a scientific team randomly collected 261 individuals of the species Squalius alburnoides, which is in the process of extinction due to habitat loss, in the Portuguese river. By studying the genetic pattern of fish, the researchers found that the genetic material stored in the nuclei of the cells of one fish was exactly the same as the one that had been collected from the nuclei of the cells of another fish in the sample. The only chromosomes of this fish were the patterns. However, mitochondrial DNA (which is stored in the mitochondria, the “energy production center” of cells) was not the same as the parent’s DNA, because this genetic information can only be given by the female.

Squalius alburnoides, usually 15 centimeters long, can be found in the Portuguese and Spanish rivers. It is a hybrid species because it was born from the cross between two species that generally cannot have offspring because they have incompatible genes.