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Female Sharks Can Reproduce Alone
mikesd81 writes "The Washington Post has an article about a team of American and Irish researchers that have discovered that some female sharks can reproduce without having sex, the first time that scientists have found the unusual capacity in such an ancient vertebrate species. Their report concludes that sharks can reproduce asexually through the process known as parthenogenesis (the growth and development of an embryo or seed without fertilization by a male). Scientists started investigating after a female hammerhead shark was mysteriously born at Omaha's Henry Doorly Zoo in a tank that housed 3 female sharks. It was originally thought one had stored sperm from a male shark before fertilizing an egg. However, baby shark's genetic makeup perfectly matched one of the females in the tank, with no sign of a male parent."
the baby should not have been genetically identical to anything in the tank unless its mother was also a parthenogen. parthenogenesis creates a homozygotic offspring that can have any random mix of the two chromosomes the mother carries for each pair. so if the mother has AB, the parthenogenic offspring can have either AA or BB, which is not identical to the mother since the mother has AB. the only way it can be identical is if the mother is also homozygotic and therefore a parthenogen.
No, you shouldn't. Hermaphrodism is the presence of sex organs for both genders. These sharks are all female. They just happen to be able to parthenogenically reproduce.
--AC
This is actually really interesting, and makes a lot of sense. Shark's genetics haven't evolved that much from its ancient relatives so this reproduction method would definitely limit variations. But I am curious as to if this is how the great white reproduces. Very little is known about the great whites breeding habits. One of the prevailing theories centers around whale carcasses.
Actually, 'immaculately conceived', in Catholic dogma, refers to the idea that Mary was conceived without Original Sin. 'Virgin birth' is what you're looking for. But it ruins so many jokes... immaculate contraption, etc.
@yg
The Ripley's Aquarium in Gatlinburg, TN has a really nice aquarium with a tunnel. They have a program called Sleeping with the Sharks that schools and other groups can participate in, allowing them to sleep in the tunnel underneath the sharks.
Dan East
Better known as 318230.
No, it wouldn't eliminate it. Its more accurate to say it would slow evolution. After all you'll still get mutations, and you'll still get selection from the environment. It just lowers the diversity and a big selection pressure (getting chosen as a mate). There was a time when asexual reproduction was the norm (bacteria, single-celled life forms), and you can see for yourself the result of that.
Bueller? Wasn't that War Games?
Right actor, wrong movie?
Thank you for the English lesson, but in Catholic dogma the "Immaculate Conception" refers to the conception of Mary without original sin. This is quite commonly confused by many with the "Virgin Birth" of Jesus. Catholic dogma views Mary's conception as a miraculous event all by its self and necessary in preparation for the later miraculous birth of Jesus.
Hopefully, you will be more likely to believe that the people at catholic.com were able to get it right.
Sexual reproduction speeds up the process among complex organisms, but bacteria evolve very quickly without it.
Sure they do. Google for "Bacterial Conjugation". Of course, they don't have genitalia like we do, but they manage anyway. Pretty much all bacteria that have been studied in any depth have been found to use conjugation to exchange DNA. There's even "bacterial porn" online, videos of the conjugation process.
Actually, most of them only engage in sex occasionally, Mostly they reproduce by cloning (i.e., dividing). When they have several populations of clones intermingling, they produce lots of random mixtures of the different populations' genes in a big orgy of conjugation. Natural selection then decides which of these mixtures deserve to survive. The result is the same sort of pooling of beneficial genes that happens in us multi-cellular organisms during sex.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
See the Komodo Dragon tale The tale explains the concept of parthenogenesis, which is simply put, "virginal birth". There are two interesting types in this : 1. Cloning, where the offspring is genetically identical to the parent 2. Selfing. where a female may produce two sets of chromosomes that mate. One set would behave like a sperm.