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This is an old revision of this page, as edited by Zvika (talk | contribs) at 18:51, 21 October 2006 (rv). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

The mouse that was created by Japanese scientists was the result of *combining* two eggs. That is completely different to development of an organism from a single egg. The entire Parthenogenesis section talks about a *single* egg.

It seems to me that if Parthenogenesis is defined as "growth and development of an embryo or seed without fertilization by a male" then the Parthenogenesis section needs two subheadings: one for development from a single egg, and another for development from two eggs.


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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

I too was told by my Biology Professor that Parthenogenesis was possible in mammals, albeit very rare. He even told us that it was possible in humans and had been documented. He told us of women who were freaked out that their daughters looked just like them, and other women who went religious because of their pregnancy. This is coming from my biology professor and I'm not sure if he was telling the truth or not. He seemed to specialize in studying swamp life more than basic genetics. SargeAbernathy 02:29, 25 April 2006 (UTC)[reply]


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?


-- 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 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

Parthenogenesis in snakes is noted in quite a few live-bearing species. Most notable are the rat snakes, with a particularly interesting article recently (2-3 mos ago) regarding a scaleless rat snake that reproduced via parthenogenesis. Will ref article once I relocate it. Other snakes with records of parthenogenic births are listed in "Snakes of the Southeast" by Chad Minter.

As for turkeys, and other birds, parthenogenesis has been noted. The following is a link to a research paper on the chemistry affecting parthenogenesis in unfertilized Turkey eggs. It is worth noting that while many birds occasionally have parthenogenic hatchings, Turkeys are considered to be the most likely to have such hatchings.

http://oregonstate.edu/Dept/animal-sciences/poultry/

Within the mammals, no natural parthenogenesis can occur.

Fictional mammalian parthenogenesis

  1. In the future, please sign your comments.
  2. Please read WP:VAND, Anakin Skywalker is alleged to be born without a father according to the Darth Vader article.

I would appreciate an apology for your comment on my talk page. Karmafist 04:48, 10 November 2005 (UTC)[reply]

Sorry I forgot to sign. But please leave the silly nonsense out of a scientific article. I have no idea what the ficitional backstory is for Darth Vader, but no one interested in biology cares about some fictional fantasy (which probably isn't parthenogenesis anyway). I did think there was some mention of the father in the very forgetable "episode one", but maybe I remember wrong.
And no... don't add Jesus, Saint Anne, Golem, or whatever other myth/fiction either. Lulu of the Lotus-Eaters 04:56, 10 November 2005 (UTC)[reply]
Hmmm... more things that don't belong in this article. From Virgin birth:
Dolly the sheep is probably superfluous too, but a moderately plausible case for a link could be made. Lulu of the Lotus-Eaters 05:28, 10 November 2005 (UTC)[reply]
Parthenogenesis is an extremely important element of mythology world-wide. Until such time as someone has written a separate article on it, I think it's entirely appropriate for this article to have a section on "Parthenogenesis in mythology and popular culture". Angr (t • c) 22:01, 15 May 2006 (UTC)[reply]

Parthenogenesis in Humans

Reference links to the study of Virgin Births in Humanity:

http://ourworld.compuserve.com/homepages/dp5/sex2.htm http://www.all.org/abac/aq0202.htm

It seems that the idea is of it being a natural oddity has been passed around, but never any clear documented case. SargeAbernathy 02:36, 25 April 2006 (UTC)[reply]

picture

Let me quote from the article about Kaguya, the mouse pictured in this article:

This is not a cloned animal because cells from two individuals are used. This cannot be called asexual reproduction, or parthenogenesis, for the same reason.

Why is this picture in the article for parthenogenesis, if it is not an example of parthenogenesis? I see someone else mentioned this above, but that post was not signed. I think that a different picture, one that actually represents the topic at hand, would be more appropriate. romarin[talk to her ] 15:06, 9 June 2006 (UTC)[reply]

I agree. Yank the picture. Having a picture of something that is specifically not parthenogenesis and says it's not parthenogenesis on the page for parthenogenesis is a bit like having a picture of a turkey on the page for a chicken and saying 'This is a turkey, not a chicken.'

However, if an image is really wanted here, speaking of, how about a turkey? As far as I know they are the only known warm-blooded animal known to undergo the process. 69.181.120.218 09:08, 16 August 2006 (UTC)[reply]

Genetic variation

Unless I am missing something central, the second paragraph

Parthenogenesis has nothing to do with artificial animal cloning, a process where the new organism is identical to the cell donor. Cloning does not require eggs. Parthenogenesis is truly a reproductive process which creates a new individual or individuals from the naturally varied genetic material contained in the eggs of the mother. A litter of animals resulting from parthenogenesis may contain all unique siblings without any twins or multiple numbers from the same genetic material, but they would all be female.

must be incorrect. Isn't it obvious that the genome of an embryo produced by a the mother without involvement of any other individual must be identical to the mother's own genome? Where would any other genes come from?

A second part of the same edit (on Aug 4 by 63.232.2.106):

Parthenogenetic populations must be all-female because there is no contribution from a male. The offspring may be capable of sexual reproduction, however, if that exists in the species.

also seems logically impossible. If the population must be all-female, how would there be any males to reproduce sexually with? Mglg 20:48, 16 August 2006 (UTC)[reply]


I think I know how this happens, but it's not obvious. In sexual reproduction, the body produces the gametes (sexual reproductive cells, i.e. ovum and spermatozoon) by meiosis, where the cells produced have exactly half the genes than a normal cell. A normal cell has always two copies of every gen, and one copy of this gen is chosen at random at the time of the meiosis. In this way, gametes have all genes, but a random copy of every gene. This is called recombination, and is one of the reasons siblings are not identical amongst themselves in sexual reproduction.

An example: say the father has to sets of genes, A and B, and the mother also two sets, C and D. So the possibilities in generating a spermatozoon are choosing a gene from pool A or one from pool B. In the mother it's the same, a gene from pool C or from pool D can be chosen. So the sons and daughters can have any of all the combinations of genes: AC, AD, BC or BD.

So let's examine parthenogenesis. The mechanism of parthenogenesis is not explained in the article (and I am not a biologist myself), but let's say the gametes are generated in the same way by the mother, an ovum and a spermatozoon. They each have half the genes of a normal cell, and a random copy of every gen. But in this case, both gametes are generated by the same body, and therefore have a random copy of the same pool of genes. So if the sets of genes are in this case A or B, and both spermatozoon and ovum have to "choose" from the same pool, the combinations are AA, AB, BA or BB (AB and BA are really the same, the order is not important).

So the daughter, born by parthenogenesis, has a random recombination of the same genes as the mother, but they are not identical.

The advantage of sexual reproduction can be seen here: genes propagate much faster, and the variability of a population is much higher.

La Vida es un Carnaval 09:26, 3 September 2006 (UTC)[reply]

Citing sources with ref tags

I would like to rearrange the citations here using <ref> tags, so that it will be easier for me to add inline citations. Anybody have an objection to this? --Zvika 19:38, 9 October 2006 (UTC)[reply]

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