Florida fish that breed still virgins – BBC

Jonathan Webb BBC

• June 2, 2015

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A group of conservationists realized by chance, doing routine monitoring of the number of individuals of the species.

Seven sawfish in Florida have become the first animals born to a virgin mother from a species so far sexually reproduced in the wild .

The discovery suggests that these births can be a natural response to the decrease in their number instead of an abnormality usually seen in captivity.

A group conservationists ran into the discovery while studying the genetic diversity of endangered species.

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These researchers say that this type of response can be more common than previously thought.

The results of his observations were published in the journal Current Biology.

Will happening in other species?

There are many species, especially among invertebrates , which naturally reproduce themselves. For example, occurs in some types of lizards, which are all female.

But for an animal that normally reproduce by mating a virgin birth is a rarity .

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And yet, some animals in captivity have virgin births

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One of the specimens studied. Its size and appearance is normal despite its unusual design.

This astonishing list of arrivals to the world includes sharks, snakes, Komodo dragons and turkeys ; all species which usually have a sexual reproduction.

And in 2012, a group of US researchers reported two pregnant snakes, wild-caught, they were brewing offspring (inside the eggs) that seemed to have no father.

But the fish saw a strange-looking beast that can grow up to four meters long, it is the first species (reproduced by mating) virgin whose offspring have been found free (and healthy) in their natural habitat.

Andrew Fields a doctoral student at the University of Stony Brook in New York and lead author of the study, says that the results were completely unexpected . The finding came for a population count of sawfish in the estuaries of Southwest Florida.

“We were following up on DNA fingerprinting saws fish found in this area in order to see if it were played between members of the same family because of the small size of its population, “says Fields

.” What genetic fingerprinting said was even more surprising: females were breeding without mating . “

Although this adaptation help delay its extinction, sawfish may not survive without the help of man.

Of the 190 specimens Fields and his colleagues counted, seven had a DNA indicated that only had one parent . Especially, these historic seven fish had identical copies of at least 14 of the 16 genes that scientists reviewed.

If they had arisen from normal forms of sexual reproduction, the team calculated that the likelihood that the animals were “homozygous” in all of these genes would be of 100,000 million

So it seemed that the seven sawfish females-all five sisters were played by “parthenogenesis”. a process by which an egg unfertilized develops into an embryo.

The researchers believe that this occurs in vertebrates when the egg absorbs an identical sister cell.

Because the resulting offspring have much less genetic diversity than usual, it is thought that their chances of survival are very low reality.

But the seven fish in the study were one year old, a normal size and were apparently well.

evolutionary strategy

The occasional parthenogenesis may be more routinely in wild populations than we thought, “said Kevin Feldheim, co-author of the study.

The researchers suggest that might be an evolutionary strategy of last resort that takes place when a population passes through a demographic blip end , as facing the sawfish, whose numbers have fallen less than 5% of those who were a century before.

But for this to make sense, the individuals themselves and infants must be fertile , so they can help the species to recover.

It is too early to know if this is the case of the seven sawfish.

The sawfish can grow up to four meters long.

Dr. David Jacoby, a marine biologist and expert on animal behavior ZSL’s Institute of Zoology, told the BBC that Florida’s findings were “interesting and revolutionary” , particularly as regards whether virgin births are a natural fit

“It’s like parthenogenesis with invertebrates. corals, crustaceans … things like that. There are examples of this occurs in vertebrates-birds, reptiles, some Sharks- but all of them in captivity, “he says.

” The fact that the finding is in nature and in species with critical levels population, definitely raises the question of whether it is a strategy that has been developed “to adjust.

But Jacoby notes, as did the same researchers, although this remarkable capacity may delay the disappearance of fish sierra, is unlikely to stop completely .

“It seems that this type of adaptation will be a way to restore the population levels,” he says. “There is a valve Exhaust “.

You may have done a natural miracle, but sawfish estuaries of Florida still needs human help to prevent their extinction.