A Komodo virgin Mary?

[Vomitore]

http://news.yahoo.com/s/nm/20061220/...ain_dragons_dc

[tigerlily]

Wow! That is pretty cool. I sure hope the remaining eggs hatch.

[Laooda]

Sweet! That gave me goose bumps! (Little Jurassic Park- nature finding a way and all)!!

[frankykeno]

How fascinating! Go Flora! Go Flora!

[lillyorchid]

Oh wow that is really cool!

[Mendel's Balls]

http://news.yahoo.com/s/nm/20061220/...ain_dragons_dc

Good find. After reading that article I did a little more exploration. It also gave me an excuse to dust off a paper (actually I opened the PDF) that I've had for some time that reported parthenogenesis in Burmese Pythons.

That paper can be found here

Groot T V M, Bruins D and Breeuwer J A J (2003). Molecular genetic evidence for parthenogenesis in the burmese python, Python molurus bivittatus. Heredity 90:130-135.

In addition, the news article from the original source, Nature, is extremely helpful in understanding the last quote from the yahoo article.

"The genetics of self-fertilization in lizards means that all her hatchings would have to be male."

http://www.nature.com/news/2006/0612.../061218-7.html

If your a more audio learner, you might be interested in this week's Nature Podcast. (See 21 Dec 2006)

Right click and save the mp3 to your desktop, open it with your favorite mp3 player and if you want fast-froward to the herp-core parts then go to 11:35 of the cast. The segment on the Komodo dragon findings is about 7.5 minutes long.

__________________________________________________________________

If you look at the primary research article from Heredity and read it carefully and compare it to the finding related in Nature this week, you'll notice that parthenogenesis isn't just parthenogenesis. In other words, That is the mechanisms and genetic consequences of parenthogenesis in Burmese pythons is different than that of komodo dragons. It also goes to show you that there are a lot of biological mechanisms for self-fertilization and asexual reproduction.

(Get out a biobook and look at meiosis and gametogenesis, also remember for birds and reptiles the female is the heterogametic sex; Females=ZW, Males are ZZ)

The mechanism in Komodo dragons occurs by a secondary polar body fusing with the the mature ovum. The offspring of this cross are always male and are not clones of their mother. They are homozygous at ever loci however(this is why they are all male reptiles-ZZ). This reduces the genetic diversity as mention in the nature article.

In the Burmese report the exact mechanism is unknown as far as I know. But all the offspring are clones and genetically identical to their mother. However, these clones lose none of the genetic diversity (i.e. the heterozygousity of their mother--and This is why they are all female-ZW)

I can see evolutionary/survival advantages to both modes of parthenogenesis.

In Komodos, the population can expand and have members of both sexes present to allow for sexual reproduction.

In burmeses, you see no inbreeding-like effects.

PS>Both studies the one in 2003 and this recent one did a good job in ruling out sperm retention as a possibility.

[xdeus]

The mechanism in Komodo dragons occurs by a secondary polar body fusing with the the mature ovum. The offspring of this cross are always male and are not clones of their mother. They are homozygous at ever loci however(this is why they are all male reptiles-ZZ). This reduces the genetic diversity as mention in the nature article.

In the Burmese report the exact mechanism is unknown as far as I know. But all the offspring are clones and genetically identical to their mother. However, these clones lose none of the genetic diversity (i.e. the heterozygousity of their mother--and This is why they are all female-ZW)

Great info! I'm curious, though, has there been any research to show what initiates the mechanism? Do all females possess this ability, or do you think it's a genetic trait that only select individuals possess? Also, is it believed to be a function of most reptiles, or only those species that may have needed it for their survival?

[Sausage]

I heard about this on the news this morning. Aren't we glad that humans aren't self-fertilizing?

[Mendel's Balls]

Great info! I'm curious, though, has there been any research to show what initiates the mechanism? Do all females possess this ability, or do you think it's a genetic trait that only select individuals possess? Also, is it believed to be a function of most reptiles, or only those species that may have needed it for their survival?

Good questions.
I'm don't think they know what initiates the facultative parthenogenesis in Komodo dragons.

From the Nature news article:

"Most zoos keep only female dragons, bringing in males occasionally for mating. Maybe this isn't enough to convince the females that a mate will be around one day, prompting her to opt for the male-free alternative."

"It makes you take a completely new look at the genetic management of your animals," Gibson says. The team suggests that zoos think about keeping male and female dragons together to avoid triggering parthenogenesis and decreasing genetic diversity."

A whole PhD Thesis could be done on this. And all kind of interesting hypotheses could be tested and explored from the organismal to the molecular level. Maybe males secrete a pheromone that inhibits the parthenogenetic pathway? Maybe there's a chemical in semen that activitely inhibits the parthenogenetic pathway?

Maybe in some species it is so rare and random of a phenomenon we just don't see it unless a female is keep in isolation away from the possibility sexual reproduction? I'd say that this possible explanation for dragons is
unlikely since they seen it in 2 out of 3 komodo in captivity in the UK and both were able then to sexually reproduce. Maybe it something about being in captivity that initiates it?


Also in Burmese....the exact cellular and genetic mechanism remain unknown. The Discussion section of the paper in Heredity discusses three possible mechanisms. 2 of which I really don't understand at this point.

The parthenogenesis seen in pythons does not present a zoo/population management issue. Genetic diversity is maintained by this unknown mechanism. There would be no unmasking of potentially harmful recessive mutations by this mechanism.


I think that many reptilian species have the capacity to do parthenogenesis. Some lizard species, in fact, only reproduce by parthenogenesis. I doubt it is controlled by just one gene. Whether some members of a given population can do it, rather than others---I Dont know.

[Pork Chops N' Corn Bread]

I read this today at school and I was amazed. Lets hope they all hatch out.
also, this could probably be moved to the Monitor section as Komodo are Varanus komodoensis(sp?)