Proof of "virgin birth"?

[davo]

Researchers from the USA and UK have confirmed that the hammerhead shark (Sphyrna tiburo) is capable of undergoing asexual reproduction.

Publishing their results in the latest issue of the journal Biology Letters, Demian Chapman, Mahmood Shivji, Ed Louis, Julie Sommer, Hugh Fletcher and Paulo Prodohl conducted genetic tests on three captive female sharks that were held in the Henry Doorly Zoo in Omaha, Nebraska.

One of the sharks gave birth to a normally developed, live female pup in the absence of any males in the aquarium for an extended period of time on 14 December 2001, and found convincing evidence that one of the three females gave birth parthenogenetically to the pup.

The researchers examined four microsatellite genotypes in all the individuals involved, and found a complete allelic match between the pup and one of the three females in the aquarium at the four loci.

The absence of any paternal genetic contribution was confirmed by amplified fragment length polymorphism (AFLP) fingerprinting.

According to the authors: "All three-candidate mothers had been held in the absence of males for 3 years, since they were wild caught in the Florida Keys as immature animals less than 1 year old.

"At least 2 years away from the age of first maturity, it is improbable that they were capable of sexual activity and sperm storage prior to capture...Moreover, the duration of sperm storage by adult female S. tiburo in the wild is relatively brief (five months...).

"None of the candidate mothers showed any sign of even rudimentary external male copulatory organs (claspers) that are typical of rare cases of intersexuality in sharks...eliminating the possibility of self-fertilization. These factors led us to consider the possibility of asexual reproduction."

Earlier this week, reported that a lone female Blacktip reef shark held at the Virginia Aquarium and Marine Science Center had also given birth to a pup in the absence of a male of the same species.

Tests are still ongoing to determine whether this was also an example of parthenogenesis, or whether the shark hybridised with another species present in its aquarium.

For more information, see the paper: Chapman, DD, MS Shivji, E Louis, J Sommer, H Fletcher and PA Prodöhl (2007) Virgin birth in a hammerhead shark. Biology Letters 3, 425–427.

Thoughts? Matt?

 

[krj-1168]

Hmmm -- Very Interesting.

But I'm pretty sure that Matt - has been aware of this "proof" for quite awhile, even thru it was only recently published. Since he's in the Business - he's usually aware of the new scientific findings from public aquariums, before the general public is.

 

[Zoodiver]

Yeah, all of these newly reported "virgin births" have been proven wrong. The issue is not that they are solitary females pupping, but that EVERY one of them have been in with a male. Nobody wants to admit that fact. Sharks are known to hold into sperm and delay embrionic development until a time best suited for survival of the species.... several years is common for most speices.

To put this in a real world set up.... you have a tank with 10 sharks. They breed. There is no need for more pups with that many animals in the area. Then, you transfer a female out to make room. She's holding viable sperm. A year or two passed and the isolated female comes to the conclusion that there are no other animals to reproduce with. Now is the time that she will pup to continue the speices. Suddenly, the news goes nuts b/c a female not in with a male just gave birth (or laid eggs if that case may be).

The real study should be on how long they can hold sperm....not this random virgin birth.

 

[davo]

well something for you to do in your spare time...

 

[hamato_yoshii]

Yeah, all of these newly reported "virgin births" have been proven wrong. The issue is not that they are solitary females pupping, but that EVERY one of them have been in with a male. Nobody wants to admit that fact. Sharks are known to hold into sperm and delay embrionic development until a time best suited for survival of the species.... several years is common for most speices.

To put this in a real world set up.... you have a tank with 10 sharks. They breed. There is no need for more pups with that many animals in the area. Then, you transfer a female out to make room. She's holding viable sperm. A year or two passed and the isolated female comes to the conclusion that there are no other animals to reproduce with. Now is the time that she will pup to continue the speices. Suddenly, the news goes nuts b/c a female not in with a male just gave birth (or laid eggs if that case may be).

The real study should be on how long they can hold sperm....not this random virgin birth.

Thanks for the real info.
I just cant imagine people making experiments look the way they want them as opposed to just stating the facts.

 

[davo]

well... it's more like covering up certain facts to get a different end result. Unfortunately happens all the time. Not sure why you'd do it though just to get your work belittled and discredited.

 

[hamato_yoshii]

well... it's more like covering up certain facts to get a different end result. Unfortunately happens all the time. Not sure why you'd do it though just to get your work belittled and discredited.

Thats because people feel the need to push their beliefs past what the facts show. It does happen all the time, it's just nice to see when the hypocrisy is pointed out.

 

[water_baby83]

Oh you'd be surprised at how often it takes place, especially in the scientific community where there is a never-ending competativeness to discover new and exciting information. This is not new or exciting, and as Matt stated earlier - they have been proven faulty. I could go into it further, but that would simply bore most of you, LOL. Simple fact is - There was a male influence in every case.

Thanks for the real info.
I just cant imagine people making experiments look the way they want them as opposed to just stating the facts.

​

 

[hamato_yoshii]

I know it takes place all the time, and I know it happens in regards to bigger more influential topics , like I said though, its nice when it gets pointed out though so hopefully people may be less inclined to just beleive everything they read.

 

[krj-1168]

Yeah - unfortunately when your dealing with the sciences - you often encounter - what could be called "Speculated Theories" - where even well-respected scientists may take facts and twist them to fit a speculation that they have. And unfortunately or fortunately(depending on your view)- it's something that happens in every scientific community - from Astrophysics to Zoology.

And usually - these "Speculated Theories" are ultimately proven false.

A couple of famous Note Worthy cases of this - in other fields include.

- From Paleontology - The T.rex Scavenger Debate.

- From Astrophysics - the Hawkin Paradox.

Still "Speculated theories" often fire up/anger other scientists in to finding facts to disprove these theories. or at very least causes other scientists to start thinking out side the normal "box" of established ideas. Which is the long run is actually a good thing.