Archiver > GENEALOGY-DNA > 2010-03 > 1268614737

From: Michael Maddi <>
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
Date: Sun, 14 Mar 2010 17:58:57 -0700 (PDT)

Diana Gale Matthiesen wrote:

Clades are not defined by their plesiomorphies (ancestral traits), but by their synapomorphies (shared derived traits), which in the case of the Y-DNA haplotree is their shared derived SNPs. Which term applies depends on your perspective (location) in the tree, but each new clade is defined by the appearance of a new derived SNP -- it's apomorphy -- not its symplesiomorphies. Here's an example...

L21+ defines a clade we call R-L21 or, as currently labeled in the ISOGG
hierarchy, R-1b1b-2a1a-2f. The clade is defined by L21+, which is a derived
trait, an apomorphy. It is not defined by it's symplesiomorphies (viz., P312+, P310+, M269+, P297+, P25+, M343+, M173+, M207+...etc.) which are shared by other clades. If you create clades based on their symplesiomorphies, such as lumping R-L21 together with R-SRY2627, which would be a valid clade based on that criterion, you end up with clades that are not monophyletic.

My reply:

I certainly don't have the expertise in cladistics that you have, but I just can not let pass what I have quoted from you above.

You claim that the only defining (pardon me, Ken) characteristic of the clade we call R-L21 is the SNP that has been named L21. You write that "It is not defined by it's symplesiomorphies (viz., P312+, P310+, M269+, P297+, P25+, M343+, M173+, M207+...etc.) which are shared by other clades."

So if a SNP shows up at the same location as L21 on the y chromosome and has the same change in nucleotide base as L21, but occurs in a man SNP-tested as in haplogroup J1, does that make that man a member of the R-L21 clade? By your definition above, it would seem to, because we should not inquire into whether the man is positive for the SNPs known to be upstream of L21 in R-L21 men, namely "P312+, P310+, M269+, P297+, P25+, M343+, M173+, M207+...etc.," to quote you again.

Ken had it right in another thread here (see ) today where he answered a question about the benefits of a full genome sequence for establishing a tree for the y chromosome. To quote him: "Full sequencing of just the y chromosome for enough males can essentially
map out the entire human y tree, and each of us males can have a branch
routing worked out back to genetic Adam 70,000 years ago or so. It will not be as complicated as you might imagine. While it may be about 2300
generations long, what will personalize the branch routing will be defined
by only about 50 or less forks in the route taken. I remember memorizing
the 50 state capitols as a kid; my grandsons could conceivably memorize and recite a little story about their 50 steps back to genetic Adam, i.e. the MRCA of all mankind's males."

The point I'm making here is that Ken's understanding of the tree and its branches and twigs means that a clade or subclade or whatever you want to call it actually represents a population descended from a common ancestor. You seem to regard each SNP as a separate event that conveniently allows us to class categories of men together without regard for their relationships to men on other twigs and branches, who are the yDNA equivalent of grandfathers, fathers, uncles, brothers and cousins. In other words, their ancestry and relationship to other men can be mapped out by SNP testing, as the quote from Ken above describes.

If I've misinterpreted what I've quoted from you about R-L21 above and you actually understand R-21 men as related somehow to men in other subclades who are "P312+, P310+, M269+, P297+, P25+, M343+, M173+, M207+...etc," please clarify for me.

Mike Maddi

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