Posted on 02/08/2008 10:57:55 AM PST by forkinsocket
Imprisoned in a tank hundreds of miles from a mate, Ibolya the female shark resorted to desperate measures. To the astonishment of her keepers, she spontaneously produced a perfectly healthy pup.
The virgin birth is making biologists think again about one of the oldest and - in evolutionary terms - most successful creatures.
"When I saw the baby shark lying on the bottom of the tank I thought it was a joke," said Attilia Varga, the director of the Nyiregyahaza Centre in Hungary. "I was amazed when I realised it was a real shark."
Ibolya, a white-tipped reef shark, has been with the aquarium for seven years. In that time, she has never shared water with a male.
The pup has been a hit with visitors - but has left keepers looking for a bigger tank. They also plan to find a male so Ibolya can breed conventionally next time.
Virgin birth - parthenogenesis - happens when an egg begins to divide without being fertilised. Common in insects, it is rare in vertebrates such as fish, birds and reptiles.
Scientists believe that sharks use it as an emergency survival mechanism. Normally animals rely on genetic diversity - the interplay of genes from two parents - to evolve. However, reproduction without sex is a useful stopgap.
Sharks are one of Nature's great survivors, appearing in the oceans 400million years ago - before the dinosaurs. Normally their eggs are fertilised inside the female.
In the white tip and most other species, the female gives birth to live young.
—wonder if they followed a star in the east??
Fun parthenogenesis fact: Since it is by definition the division of an egg without the action of sperm, all parthenogenic offspring are female.
I would like to introduce my parthenogenic sister. Her name is Bud.
And one at mine who got pregnant from the basketball team...
Yep. In science there are the dogma pushers and then the free thinkers.
The dogma pushers try to become walking, talking encyclopedias, I guess so they feel like they know everything.
The free thinkers try and approach problems at different angles and spend a lot of time, well, thinking.
The Dogma pushers outnumber the free thinkers greatly and often seem the most on the ball, but really are poor researchers.
A free thinker would not even bat an eye at this, but would smile or laugh in delight.
A dogma pusher would react with shock and frown in anger.
>>Are they absolutely sure they haven’t seen any attorneys near the tank?<<
BU-DUM CHING!
“Besides, discovery is a part of science. New discoveries improve science, and not the other way round.”
As long as scientists discover, and not invent. As long as they discover and not teach hypotheses as facts.
—wonder if they followed a starfish in the east??
But that doesn’t stop most of them from presenting their next theory as 100% indisputable fact.
Quite true. They have a certain kinship with people who present their particular interpretation of a given Bible passage as a 100% indisputable fact.
No, but Bill “Sleeps with Sharks” Clinton visted a few months ago.
That goes to everyone, and especially the detractors; not just scientists. And that too, even more so.
there are frogs and fish that do that
Tramp.
This reminds me of a story about it raining 6 inches of beer at some university. They did find 6 inches of beer in the rain gauge, so, should it be assumed it rained 6 inches of beer?
Well, just as some trickster poured beer in the rain gauge, maybe some smart aleck put a new born shark in the tank. Seems more likely to me than the other explanation.
it was a starfish the wise tuna followed
I'm amazed that many would have been happy if science had never questioned that 'fact' of a Geocentric Universe.
While this has been noted before, it hasn’t been widely reported, http://www.slate.com/id/2168092/ but I did find this:
Brave Old World
What Dad didn’t tell you about the birds and bees.
By William Saletan
Posted Saturday, June 9, 2007, at 6:19 AM ET
“An egg that fertilizes itself makes two identical sets of chromosomes, including sex chromosomes. In birds, snakes, and most lizards, two identical sex chromosomes make a male. That allows parthenogenesis to function as a DNA survival mechanism, since an isolated female—close your ears, kids—can produce a son and mate with him. But in sharks or mammals, this wouldn’t work, since two identical sex chromosomes—XX—make a female.
Or so we thought. Three weeks ago, Biology Letters delivered the second surprise: “Virgin birth in a hammerhead shark.” A perfectly formed baby shark had appeared in a tank in Nebraska. Tests proved she, too, was a parthenogen.
Why hadn’t we found parthenogenesis in these animals before? Because we hadn’t looked. Several sharks have mysteriously reproduced in captivity in recent years. Scientists now think parthenogenesis is responsible. Of the two sexually mature female Komodo dragons in Europe, both are now known to have reproduced this way. Every parthenogenic dragon is male, which may explain in part why males heavily outnumber females. In snakes, the array of known parthenogenic species continues to grow.
For explaining everyday life—babies, puppies, puberty—the mommy-daddy story of procreation works fine. But at life’s edges, conventional biology, like conventional physics, breaks down. As you approach the speed of light, time slows and distances shrink. And as you approach extinction, genes find new ways to pass themselves on. Scientists call it “reproductive plasticity.” A Komodo dragon manufactures a mate. A shark’s got to do what a shark’s got to do.”
Cue Jeff Goldblum /Jurrasic Park Reference
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