Does anyone know if mitochondrial DNA is the same in maternal-(monozygotic) twins

[Michaelangelica]

Does anyone know if mitochondrial DNA is the same in maternal-(monozygotic) twins?

[CraigD]

Among all mammals and many other sexually reproducing organisms, the mitochondria for all offspring of a given mother, regardless of the father, have DNA differing only due to mutations. So not only identical and fraternal twins, but full and half siblings share identical or nearly identical mtDNA.

[Michaelangelica]

Originally Posted by CraigD

Among all mammals and many other sexually reproducing organisms, the mitochondria for all offspring of a given mother, regardless of the father, have DNA differing only due to mutations. So not only identical and fraternal twins, but full and half siblings share identical or nearly identical mtDNA.

Thanks CraigD,.

So the mother passes on the same mitochondrial DNA in her every pregnancy, twins or not?
Sisters born 5 years apart would share the same mitochondrial DNA?
(given no mutations)

So does this mean we would be able to trace a race's genetic history via MDNA?
or do we all basically share "Eve's" MDNA?
Is there a set rate of change?

The father does occasionally pass on a little mitochondrial DNA.
I am not sure how much, or how often, or even why. Do you know?

[Galapagos]

Originally Posted by Michaelangelica

?

These might help:

Mitochondrial Eve - Wikipedia, the free encyclopedia

Paternal mtDNA transmission - Wikipedia, the free encyclopedia

edit- also may be relevant:
Medical News: Ancestry Testing Has Limitations, Genetics Society Warns - in Genetics, Genetic Testing from MedPage Today
How Accurate Is Your Family Tree? -- Couzin 2008 (1113): 4 -- ScienceNOW

[CraigD]

Originally Posted by Michaelangelica

So the mother passes on the same mitochondrial DNA in her every pregnancy, twins or not?

Yes, she does.

Sisters born 5 years apart would share the same mitochondrial DNA?
(given no mutations)

Yes.

So does this mean we would be able to trace a race's genetic history via MDNA? … Is there a set rate of change?

Yes and yes. The rate at which mtDNA mutates is theoretically and empirically understood with good confidence to be a fairly constant, known rate. From this, measurements of variations in mtDNA of humans living now, and some assumptions about ancient travel and mating behavior, we’re able to estimate the age of “mitochondrial Eve” at roughly 140,000 years.

… or do we all basically share "Eve's" MDNA?

Because different lines of maternal descent experienced different mutations, people who don’t share a recent female ancestor have different mtDNA, and different mtDNA than mtEve.

Note that this doesn’t mean mtEve was the first human female, or that no female before her have any present day descendents. The linked wikipedia article has a pretty good debunking of these misconceptions.

Originally Posted by Michaelangelica

The father does occasionally pass on a little mitochondrial DNA.
I am not sure how much, or how often, or even why. Do you know?

According to the wikipedia article, there’s one know case of this in humans, described in the 8/22/2002 NEJM article "Paternal Inheritance of Mitochondrial DNA" (Schwartz and Vissing). The authors speculate that this was because of a mutation in the subject’s father’s mtDNA that allowed it to overcome the usual mechanism that eliminate paternal mtDNA, especially a possible aberrant gene causing it to reproduce many times faster than normal, or several genes that caused it to be unrecognized by the factors that are believed to usually destroy paternal mtDNA. They also speculate that some infertility treatments have the prospect of passing paternal ntDNA to children, but don’t document any cases in humans.

In short, inheriting mtDNA from ones father appears to be very rare in humans.

[Michaelangelica]

Originally Posted by CraigD

In short, inheriting mtDNA from ones father appears to be very rare in humans.

Thanks very much everyone, especially Craig

What got me going on this, was a mention and a footnote in the book 1491.(p. 139)
The author Charles Mann mentions some mtDNA "archaeology".
It seems 96.9% of native Americans/Amerindians share one of four "haplogroups" (people with similar mtDNA).
Three of these four groups are also common in Southern Siberia. (found by Douglas Wallace in 1990)

Estimates of when the original haplogroup migrated to the Americas is 22,414-29,545 years ago ( p. 166).

O, they give the rate of mtDNA change too,- 0.2 to 0.3% every 10,000 years ! (So much info in this book hard to remember it all and I have read it three times now)

The forth haplogroup ("A") left Asia 33,000 to 43,000 years ago (Bonatto and Bolzano)
Research by the archaeologist C. Vance Haynes & Pena (Brazilian geneticist) is still ongoing.
------------------------

In the footnote Mann says this

"I use the hedge word "basically", almost, and "in essence" because sperm actually have 50-100 mitochondria, just enough to power them though their short lives. By contrast, the egg has as many as 100,000 mitochondria. When the sperm joins the egg, the egg eliminates sperm mitochondria. Every now and then, though, a few escape destruction and end up in the embryo's cells

This would be interesting

Search results
From Wikipedia, the free encyclopedia
You searched for Mitochondrial DNA Australian Aboriginal (all pages starting with "Mitochondrial DNA Australian Aboriginal" | all pages that link to "Mitochondrial DNA Australian Aboriginal")
Jump to: navigation, search
No article title matches

as date of Aboriginal arrival in Australia is variously estimated at between 40,000 to 70,000 years ago Most go for 40-50,000. But they were supposed to have settled briefly in S. America too. Here is one article on the subject
http://www.cosmosmagazine.com/news/1...ralian-origins
Tthis is a bit more technical and beyond me
http://journal.shouxi.net/html/qikan...08_345785.html

BTW
I have mentioned it before but how do I get larger type when writing posts?
I am finding the new small type difficult to read and edit