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Archiver > GENEALOGY-DNA > 2003-12 > 1070756624


From: "Louis" <>
Subject: Re: [DNA] Query on Haplogroups
Date: Sat, 6 Dec 2003 16:23:44 -0800
References: <18a.22fc0142.2d037df0@aol.com>


Ann and others:

Ann, a very nice explanation of "Identical by Descent" (IBD) versus
"Identical by State" (IBS). I usually call "Identical by State" by the
term "Convergent Evolution".

However, this raises more questions for me, even though they may have simple
answers. But I want to make sure I am understanding this correctly. So
here are my questions

Let's take my situation: I SNP tested positive for Y Haplogroup G, and
has 12 markers STR tested (from Family Tree DNA). Now, comparing my
results to othere people who have had BOTH SNP and STR test for their given
sample, I find the following: I am a 3 step difference from an O1 male,
in terms of my STRs. And I am a 4 step difference from another G male, in
terms of STRs.

1) Can I say with 100% confidense that my closeness to the O1 male is due to
Identical by State" (IBS) or Convergent Evolution, rather than Identical by
Descent (IBD)?

2) In other words, when comparing different Haplogroups, at what point can
you be sure something is IBS vs. IBD? Do the lines get more blurry when
comparing sub-Haplogroups, such as R1b3 vs. R1b4, since they are much more
closely related?

Thank you,
Louis Loccisano


----- Original Message -----
From: <>
To: <>
Sent: Saturday, December 06, 2003 10:46 AM
Subject: Re: [DNA] Query on Haplogroups


> In a message dated 12/06/03 8:44:46 AM Pacific Standard Time,
> writes:
>
> > <<The more recent the
> > SNP, the more likely you are to find the same haplotype in different
> > haplogroups.>>
> > Ann Turner - GENEALOGY-DNA List Administrator
> >
> > Question: If genetic DNA change only occurs in one person and is then
> > transmitted through inheritance to others (as DNA scientists seem to
say)
> > should not all haplotypes be in the same haplogroup?
> > The reality is (as far as I understand) that most haplotypes are mostly
in
> > the same haplogroup but there are numerous exceptions as the above
> > sentence suggests.
>
> A SNP (Single Nucleotide Polymorphism) is a one-time event (or Unique
Event
> Polymorphism) that defines the beginning of a new haplogroup. All the
> descendants of the person with the SNP will pass it on to the next
generations.
>
> The person who has the SNP also has a haplotype, as defined by the Short
> Tandem Repeats that the genealogical companies test. This haplotype is the
> starting point for 100% of the descendants in the new group. STRs mutate
more
> frequently, and the number of repeats can go up or down. The longer ago a
SNP
> occurred, the greater the variety of haplotypes in the haplogroup.
>
> But the founding father of the new haplogroup probably had brothers and
> cousins of various degrees who had the same haplotype. Their descendants
don't have
> the new SNP, so they stay in the old haplogroup, but they are starting
with
> the same haplotype. Their descendants start accumulating variations in the
> haplotypes, too. The longer ago a SNP occurred, the more likely that the
> haplotypes have been diverging along different random pathways. The more
recent the
> SNP, the more likely you are to find that some people have preserved the
original
> haplotype. If the haplotype has been preserved, then all those people are
> "Identical by Descent" (IBD).
>
> But people can also be "Identical by State" (IBS). That can happen when
they
> start out with different haplotypes, but the mutations just happen to be
in
> directions that make them more similar. Say for example, two people living
a few
> hundred years ago had these haplotypes:
>
> 11-11-11-11-12-13-11-11
> 11-11-11-11-13-12-11-11
>
> Their common ancestor probably lived several hundred years or more
earlier.
> If a descendant of person #1 has a mutation in the fifth marker that
changes it
> to a 13, and a descendant of person #2 has a mutation that changes the
sixth
> marker to a 13, then both people end up
>
> 11-11-11-11-13-13-11-11
>
> That's called convergence. They are IBS, and it's just accidental that
they
> end up with the same haplotype. That's not a practical concern over a
> genealogical time frame, however, since the mutations are rare to begin
with, and the
> mutations would have to fall on exactly the right markers.
>
> Ann Turner - GENEALOGY-DNA List Administrator
> Search or Browse the archives, Subscribe or Unsubscribe at
> http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
>
>
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