GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2009-07 > 1248312709


From: "Ken Nordtvedt" <>
Subject: Re: [DNA] Coalescence vs. MRCA vs. founder
Date: Wed, 22 Jul 2009 19:31:49 -0600
References: <COL109-W558AEC9973B6AAC7A0381BDE1B0@phx.gbl><016801ca0b1d$3fce6b10$6400a8c0@Ken1><SNT115-W26FC461DFDC3D8589123B9CC180@phx.gbl>


There is no way at all to estimate age back to happening of an snp. You can
just estimate age of a node that must be further back in time and another
node that must be closer to the present. The snp happened sometime between
those events; that's all you can determine. SNP events are not age
estimated!

intraclade self variance estimates the average age back to the MRCA of each
pair of haplotypes in your sample population. Draw any tree: you see that
age is younger than age to the overall MRCA. For instance; if I and my 3rd
cousin are both in the sample population, our ancestral lines most likely
converge close to the present compared to the whole sample population's
MRCA.

MRCA of a sample population is most recent ancestor to ALL the sample
population. Any haplotype pair must have its pair MRCA equal to or more
recent than the MRCA for the entire sample population.

MRCA of a clade is same thing as "founder" of the clade.

Ken
----- Original Message -----
From: "Steven Bird" <>
To: <>
Sent: Wednesday, July 22, 2009 7:16 PM
Subject: [DNA] Coalescence vs. MRCA vs. founder


>
> Ken wrote:
>
> Coalescence age is younger than age to the MRCA.
>
>
>
>
> I reply:
>
>
>
> What?? MRCA means "most recent common ancestor." MRCA would be exactly
> the same thing as coalescence, would it not? I'm guessing that you may
> mean "founder" of the clade, that is, the first individual exhibiting the
> SNP in question? Not trying to be flip, just seeking some clarity.
>
>
>
> Steve
>
>
>
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