Talk:Parthenogenesis
From Academic Kids
My genetics course said that parthenogenesis in mammals is impossible, or at least extremely difficult. Obviously, there are examples of experiments on this main page, but I suspect they had problems with this: parthenogenesis is difficult for mammals because mammals posses a unique genetic characteristic: X-linked innactivation. The general idea is that mammals, more so than other vertebrates, are likely to have a female inseminated by more than one male at a time, and to actually have embryos within the same womb from different fathers. This led to the natural selection directed process whereby certain genes from the male chromosomes are methylated, turning them off, etc. and this tends to give that male's embryo's an advantage over the others. Meanwhile, the other embryos are doing the same thing; this leads to a tug of war, essentially, while at the same time the mother's genes in the embryo are methylated in a way that will favor the survival off all of the embryos. --->At any rate, the practical result is that if two DNA strands from only the mother were to combine (the parthenogenesis process as it normally occurs in certain lizards), the resulting mammal embryos would lack essential X-linked inactivations. X-linked innactivation mistakes, when they occur naturally in humans because of non-disjunction, etc., cause crippling genetic disorders in humans, i.e. "Laughing Puppet Syndrome" and others. I would imagine that any live parthenogenesis mammal births would suffer from devastating genetic syndromes. More research for the wiki article needs to go into that---Ricimer, April 12, 2005
Unless someone has a source to back up the claim that snakes can reproduce by parthenogenesis, it should be removed (as I have done) and stay removed.
Parthenogenesis is well noted in some species of lizards and salamanders (such as the Jefferson's Salamander and various Blue Salamander hybrids) for which there are no males. I'm unaware of anything remotely like that in snakes, unless you want to count false pregnancies (where a female snake which has not been impregnated lay unfertilized eggs, or in the case of ovoviviporous [spelled wrong, trust me] snakes, weird jelly-bean-like nuggets).
I know enough about reptiles and amphibians that I'm comfortable making those edits, but I'm not so sure about Turkeys... Anyone have some evidence they wanna post?
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I've just done some research and parthenogenesis has occured in some snakes, but it is by no means a common occurence (as it is with whiptails and some salamanders) and is not very well understood. As far as I could find are four known occurences (one timber rattlesnake which produced one litter, one wandering garter snake which consistently produces litters for ten years, a brahminy blind snake, and one other snake).
Sharks
It would be nice to have some information about Sharks on this page. Here's a general article (http://news.nationalgeographic.com/news/2002/09/0925_020925_virginshark.html) on putative parthenogenesis in Sharks. --Viriditas 10:13, 7 Sep 2004 (UTC)
The exact process, difference in parts involved and biochemistry, etc, still needs expansion and explanation. --Tchalvak
