Captive shark had 'virgin birth'
The bonnethead is a species in the hammerhead group
Female hammerhead sharks can reproduce without having sex, scientists confirm.
The evidence comes from a shark at Henry Doorly Zoo in Nebraska which gave birth to a pup in 2001 despite having had no contact with a male.
Genetic tests by a team from Belfast, Nebraska and Florida prove conclusively the young animal possessed no paternal DNA, Biology Letters journal reports.
The type of reproduction exhibited had been seen before in bony fish but never in cartilaginous fish such as sharks.
Parthenogenesis, as this type of reproduction is known, occurs when an egg cell is triggered to develop as an embryo without the addition of any genetic material from a male sperm cell.
See how parthenogenesis takes place
The puzzle over the hammerhead birth was reported widely in 2001, but it is only with the emergence of new DNA profiling techniques that scientists have now been able to show irrefutably what happened.
The investigation of the birth was conducted by the research team from Queen's University Belfast, Nova Southeastern University in Florida, and Henry Doorly Zoo itself.
The scientists say the discovery raises important issues about shark conservation.
In the wild, these animals have come under extreme pressure through overfishing and many species have experienced sharp declines.
If dwindling shark groups resort to parthenogenesis to reproduce because females have difficulty finding mates, this is likely to weaken populations still further, the researchers warn.
The reason is that asexual reproduction reduces genetic diversity and this makes it harder for organisms to adapt - to changed environmental conditions or the emergence of a new disease, for example.
With normal sex, the mixing of maternal and paternal DNA introduces genetic novelty which can give animals new traits that might be advantageous in their new circumstances.
Sex marks
Dr Paulo Prodohl, a co-author on the Biology Letters paper from Queen's School of Biological Sciences, said: "Vertebrates in general have evolved away from parthenogenesis to boost genetic diversity and enhance evolutionary potential.
"The concern for sharks is that not only could we be reducing their numbers but we could be making them less fit as well."
"Our findings will now have to be taken into consideration for any conservation management strategy, especially for overexploited species."
The birth of the hammerhead (of the bonnethead species, Sphyrna tiburo) at Henry Doorly was as tragic as it was puzzling.
The new pup was soon killed by a stingray before keepers could remove it from its tank.
At the time, some theorised that a male tiger shark kept at the zoo could have been the father - but the institution's three bonnethead females had none of the bite marks that are usually inflicted on their gender during shark sex.
Some even suggested that one of the females could have had sex in the wild and stored the sperm in her body - but the three-year period in captivity made this explanation highly unlikely.
The new tests on the dead pup's tissues now show the newborn's DNA only matched up with one of the females - and there was none of any male origin.
Although extremely rare in vertebrates, parthenogenesis (out of the Greek for "virgin birth") occurs in a number of lower animals. Insects such as bees and ants use it to produce their drones, for example.
Christ returns as a shark (Shark has virgin Birth)
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Christ returns as a shark (Shark has virgin Birth)
http://news.bbc.co.uk/1/hi/sci/tech/6681793.stm
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Libertarian philosophy can be boiled down to the phrase, "Work Will Make You Free."
In Libertarianism, there is no Government, so the Bosses are free to exploit the Workers.
In Communism, there is no Government, so the Workers are free to exploit the Bosses.
So in Libertarianism, man exploits man, but in Communism, its the other way around!
If all you want to do is have some harmless, mindless fun, go H3RE INST3ADZ0RZ!!
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Other than the fact that the hammerhead shark is likely to go extinct because of the lack of genetic diversity that will result from this its pretty cool, although a worrying development for the future of us males.
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I'm not clear however if this is a feature of a single genetic anomaly or of the species as a whole.
Worship the Virgin Jaws
I'm not clear however if this is a feature of a single genetic anomaly or of the species as a whole.
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If they can't even find males, they're doomed either way. Though I do see reproducing asexually will keep at least a female population for the low quantity males to mate with in case the mothers die off.
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Unlikely. This asexual reproduction is likely not anything new for the species, so they probablely had the ability for quite a while now and are still doing fine. This asexual reproduction, also, doesn't mean that sexual production is out of the question, it just means that in times of mating need, the females can extend their genetic lineage longer and thus actually benefit the species as a whole.Darth Tanner wrote:Other than the fact that the hammerhead shark is likely to go extinct because of the lack of genetic diversity that will result from this its pretty cool, although a worrying development for the future of us males.
Considering the benefits of the feature from an evolutionary perceptive, and my belief that it's actual a devolutionary effect (sharks likely evolved from sexually reproducing ancestors), I can only imagine that the feature is widespread in the shark population, if not universal.I'm not clear however if this is a feature of a single genetic anomaly or of the species as a whole.
As big as the ocean is, I can understand parthogenesis as a survival feature, when there may not be males available for hundreds of miles.
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I think I need to point out here that Shark Jesus was a girl.
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Parthogenesis definitely makes sense as a survival technique in the ocean, where there may not be another member of your species around for miles. If there were no males in the enclosure, it makes sense that the shark would use it to continue it's line.
Congratulations, you just contributed nothing to the discussion. Here's your spam award.Darth Mortis wrote:I, for one, welcome our new aquatic overlord.
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Epic fail.Darth Mortis wrote:I, for one, welcome our new aquatic overlord.
This is fairly interesting. Obviously, if this were the only means of reproduction available, it would be ultimately pernicious to the survival of the species. But as a secondary means of reproduction, where it won't be an actual replacement for sexual reproduction, it can be advantageous. One thing to keep in mind is that it only serves to protect female genetic material. A male that can't find a mate is SOL either way.
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Only if they fight in 12 feet of snow. Its neutral ground for our saviors to duke it out in.Kuja wrote:You realize, of course, that there is only one way this can end.Admiral Valdemar wrote:I remember when only copepods were doing this. Now every bloody species wants to have a go.
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But.. but.. cloning is UNNATURAL!
Still this is pretty damn cool and I must make a note to convert to Shark Christianity sometime soon...the question is do we get to keep the loaves at least? I understand the messiah will definitely want the fish but then with some of the stuff you find in shark stomachs she might want the bread to which seems kinda grabby..
Still this is pretty damn cool and I must make a note to convert to Shark Christianity sometime soon...the question is do we get to keep the loaves at least? I understand the messiah will definitely want the fish but then with some of the stuff you find in shark stomachs she might want the bread to which seems kinda grabby..
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Are you shitting me? Do you have any idea how long sharks have existed without any major design alteration? They aren't specialized for a single type of prey (at least many aren't): they're simply highly adapted for a life spent constantly in motion (they can't pump water through their gills, which is why they must swim to breath).Big Orange wrote:Sharks seem to be rather thoroughbred anyway and far too biologically specialized - thoroughbred and and over specialized species have a nasty habit of going bye bye out in the wild...