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Convergence

Some men have very common yDNA haplotypes, as reflected by STR markers. They may have hundreds to thousands of "close matches", even at 67 markers and hundreds at 111. They have too many matches to be able to follow up on them properly.

This page is for those who suffer convergence.

What is Convergence?

Convergence describes a phenomenon in which organisms of different phylogenies (ancestries) evolve toward common forms. This is seen in in the outward forms of many different plants and animals, including humans, and may be due to evolutionary forces.


Euphorbia obesa

Astrophytum asterias
The plants above look very much alike though only distantly related.
Marine animals with similar body types and anatomy.

Evidence is growing that convergence also occurs with ySTR haplotypes. We are seeing men reported with close matches who -- based on their SNPs -- can not be related within two thousand or more years. One expert has termed these "coincidental matches".

Some have suggested that the phenomenon we see is at least partly due to lack of divergence. That is, a few very ancient haplotypes (from before surnames were adopted) have not mutated to different forms. We'll also include this possibility in "convergence".

Definition

For this discussion, we'll operationally define convergence as sufficient similarity between haplotypes of different paternal origins as to be displayed on a FTDNA match list, meaning

Some may invoke ySNPs in the definition. While a conflict in ySNPs (meaning men can not share the same patriline within genealogic time) is the "acid test" for convergence, it does not necessarily reflect all convergence.

Is it real? Does it actually happen?

Yes. The phenomenon has been seen but not thoroughly investigated.

Strong evidence comes from the Clan Irwin project where exact matches exist between 30 participants at 37 markers and 12 at 67 markers. Yet, the genealogies show no common ancestors for at least eight generations. There is only miniscule probability (p << 0.0001) that an ancestral haplotype could remain unchanged to yield exact matches so many DNA transmissions later. It is more likely that they mutated toward common forms from different sources.

Within the Taylor Family Genes project we also see highly similar haplotypes between men of different subclades, usually of
R-M269. Because the subclades separated thousands of years ago, we know they can not share the same paternal ancestor within genealogic time and the matches.

How common is convergence??

A single instance of convergence is enough to establish its existence but says little about prevalence. We try to answer this question (though perhaps crudely) using data from Taylor Family Genes. The graph to the right and the table below show the distribution of project members by number of FTDNA-listed out-of project & other-surnamee matches at 37 markers.


 

.
"Extra-project" Matches @ 37 markers
Statistic Value  
Median 3     
Mean 18.27  
Max 390     
St. Dev'n. 42.233
n 524     
Histogram
Category Number Percent
0 105 20.0%
1-5 212 40.5%
6-10 51 9.7%
11-20 50 9.5%
21-50 56 10.7%
51-100 27 5.2%
100+ 23 4.4%
The above data (all haplogroups) were taken from ongoing recording of matches, by in-project matches (including non-participants with project surname) versus extra-project matches (non-participant and other surname). Participants assessed to be of non-Taylor paternity (non-Taylor surname plus no in-project matches) have been excluded.

Possible signs of convergence are seen in ~80% of project members' haplotypes. However, convergence is high (>20 extra-project matches) for only 20% and very high (>50) for only 10%.

Convergence is more commonly seen at lower resolutions than higher and at greater genetic distances than lesser.  Common haplotypes (see our study) may be the result of convergence.

How do I tell if this applies to me?

The number of matches on your match list at 37 or more markers is the first hint. More than 50 is a good clue; few men have that many genetic cousins who've tested DNA. If you have an unusually high number of matches, you may see a recommendation above your match list to upgrade to more markers; this may be a good idea.

Another clue is the variety of surnames. If the names are all different and there's no apparent pattern to them, this could be you. (Though, if one surname dominates the list, this could signal an NPE.)

Do you have a WAMH or Niall badge on your results? Do you come close to matching either 12-marker haplotype? These haplotypes within R1b are extremely common and men who have them or come close tend to have many matches.

The last, most important, clue is SNP results and haplogroups or subclades. If these conflict, the match does not indicate a common ancestor within genealogic time. For example,,

See also match validity below.

Why?

The reasons for this phenomenon are not well-understood, but may include:

What to do?

The best strategy is to eliminate coincidental, irrelevant matches from consideration without -- at the same time -- eliminating relevant and meaningful matches.

SNP Testing

Testing, to identify matches of a different subclade, is the recommended strategy. Unfortunately, both parties to the match will need to test SNPs as far downstream as possible for this method to work.

Several SNP testing options exist but we regard few of them as completely satisfactory. They are either too expensive or incomplete. Exceptions are recent offerings by FTDNA of "SNP Packs" or "Backbone Panels"; they are fairly complete, testing 100+ SNPs per bundle, and reasonably affordable, in the neighborhood of $100 or $1 per SNP. See our page on them.

Test more STR markers

It has been a common strategy for men with many matches to test up to 111 markers and ignore matches at lower levels. This does reduce the match list and, to some extent, focuses the list more closely.

The problem here is that it also eliminates possibly significant and meaningful matches at lower levels (e.g., at 37 markers). If your match partner hasn't tested above 37, you won't see the match at 67 or 111.

Is a ySTR match valid?

More than two-thirds of Taylor Family Genes project members are in subclades of R1b1a2a1a (R-M269, R-P310, see note below) About 10% of these have many coincidental matches, which do not indicate common paternal ancestry within genealogic time.

This is mostly a matter of elimination. To see if a STR match is invalid, check to see if tested SNPs conflict. Different "terminal SNPs" are not necessarily conflicting; one may may downstream of (included within) the other. 

  1. Check SNPs of each member of the close-matching pair. Both must have tested positive for SNPs listed in a  column of the table below; if not, this tool can not be used.
  2. If one member has an SNP in the pink column and the other has a SNP in the green column, the match is invalid.
  3. If both have SNPs in the same column, both must be in same subclade, for the match to be valid, e.g.,
    1. L20 and L21 or M228.2 are not inconsistent. L21 is in a subclade of L20 and M228.2 is in s subclade of L21.
    2. M126 and M160 are in conflict; they are in different subclades, ..1b3a and ..1b3b

A match is not necessarily valid if this tool fails to identify it as invalid. However, the chances are reduced.

YCC (FTDNA) Subclades of R1b1a2 a1a
FTDNA
SNP
YCC
Tree
  FTDNA
SNP
YCC
Tree
U106 ..1a* P312 ..1b*
U198 ..1a1 M65 ..1b1
P107 ..1a2 M153 ..1b2
L1 ..1a3 U152 ..1b3
L48 ..1a4 M126 ..1b3a
 L47 ..1a4a M160 ..1b3b
 L44/L163..1a4a21 L2 ..1b3c
 L46 ..1a4a1a L20 ..1b3c1
  L164..1a4a1a1 M228.2 ..1b3c1a
 L148..1a4a4b L196 ..1b3c2
L188..1a4a4c L4 ..1b3d
L6..1a5 L21 ..1b4
P89.2..1a6 M27 ..1b4a
L217..1a7 M222 ..1b4b
L257..1a8 P66 ..1b4c
L325..1a9 L96 ..1b4d
L144/L196 ..1b4e
  L159.2 ..1b4f
L193 ..1b4g
L226 ..1b4h
P314.2 ..1b4i
L176.2 ..1b5
SRY2627 ..1b5a
L165 ..1b5b
* Note: Be aware of recent changes in the R1b1a2a1a phylogenetic tree, due to continuing scientific discoveries. The more recently updated phylogeny is the ISOGG tree. FTDNA uses the 2010 Y-Chromosome Consortium (YCC) tree, with some additions. The two nomenclatures are not entirely consistent with each other.
 
In the FTDNA tree (used above), subclades of R-U106 are R1b1a2a1a1a.. and subclades of R-P312 are R1b1a2a1a1b. In the more up-to-date ISOGG tree (below), R-U106 subclades are R1b1a2a1a1.. and R-P312 subclades are R1b1a2a1a2..

ISOGG Tree of R1b1a2a1a,
as of April 2014
SNPs Phylogenetic - SNPs Phylogenetic.
M405/S21/U106 ..1 P312 ..2
L217.1/S1849.1 ..1a DF27/S250 ..2a
S493/YSC000053/Z18, Z19 ..1b S227/Z195, S355/Z196 ..2a1
Z14 ..1b1 S230/Z209, S356/Z220 ..2a1a
S375/Z372 ..1b1a Z216, S181/Z278 ..2a1a1
L257/S186 ..1b1a1 S348/Z214 ..2a1a1a
DF95/S21484 ..1b1b M153 ..2a1a1a1
S263/Z381 ..1c L176.2/S179.2 ..2a1b
S264/Z156 ..1c1 Z262 ..2a1b1
S265/Z304, S376/Z305, S497/Z306, S498/Z307 ..1c1a M167/SRY2627 ..2a1b1a
DF98 ..1c1a1 L165/S68 ..2a1b2
L128/PF3499 ..1c1a1a CTS4188 ..2a1b3
DF96/S1809 ..1c1a2 DF17/S455 .2a1c
L1/S26 .1c1a2a L617 ..2a2
P89.2 ..1c1a2b L881 .2a3
S499 ..1c2 PF6570/S28/U152 .2b
M467/S29/U198 ..1c2a L2/S139 ..2b1
L48/S162 ..1c2b S255/Z367 ..2b1a
L47/S170 .1c2b1 L20/S144 ..2b1a1
L44/S171, L163/S352 .1c2b1a S368/Z34 ..2b1a2
L46/S172 ..1c2b1a1 S487/Z35 ..2b1a2a
L45/S353, L164/S502, L237, L477, L493 ..1c2b1a1a Z275 ..2b1a2a1
Z159, Z160, Z350 ..1c2b1b L196 ..2b1b
S268/Z9, S379, S504/Z28, Z348 ..1c2b2 Z49 ..2b1c
S271/Z30 ..1c2b2a S211/Z142 ..2b1c1
S511 ..1c2b2a1 L562/S213 ..2b1c1a
S272/YSC0000049/Z7, S509/Z31 ..1c2b2a1a S206/Z36 ..2b2
S384/YSC000047YSC000050/Z8, Z21, Z22, Z24, Z25, S517/Z26, Z29, S516/Z351 ..1c2b2a1a1 PF6601/Z56 ..2b3
S274/Z11 ..1c2b2a1a1a L4/S178 ..2b3a
S385/Z12 ..1c2b2a1a1a1 S47 ..2b3b
L148/S173 ..1c2b2a1a1a1a Z144, PF6578/S371 ..2b3c
S275/YSC0000043/Z1 ..1c2b2a1a1b L21/M529/S145, L459, S461 ..2c
S514/Z344 ..1c2b2a1a1 b1 CTS241/DF13/S521 ..2c1
S276/Z6 ..1c2b2a1a1 b1a DF49/S474 ..2c1a
S512/Z346 ..1c2b2a1a1 b2 DF23/S193 ..2c1a1
S387/Z343 ..1c2b2a1a1 b2a Z2961 ..2c1a1a
CTS7080/S3334 ..1c2b2a1a1 b2a1 M222/Page84/ USP9Y+3636 ..2c1a1a1
DF101 ..1c2b2a1 a1b2b DF85/S675 ..2c1a1a1a
DF102 ..1c2b2a1a1 b2b1 DF1/L513/S215 ..2c1b
M365.4 ..1c2b2a1a 1c P66_1, P66_2, P66_3 ..2c1b1
CTS10893/S3595 ..1c2b2a1a2 L193.1/S176.1 ..2c1b2
S1743/Z331, Z334, Z347 ..1c2b2b L706.2 ..2c1b3
S505/Z330 ..1c2b2b1 L705.2/S465.2 ..2c1b3a
Z326, S380/Z329, Z337 ..1c2b2b1a CTS3087 ..2c1b4
CTS2509/S1734, S1741/Z319, Z325 ..1c2b2b1a1 L96 ..2c1c
L200 ..1c2b3 L144.1/S175, L195/S354 ..2c1d
L199.1 ..1d S219/Z255 ..2c1e
L159.2/S169.2 ..2c1e1
S218/Z253 ..2c1f
L554 ..2c1f1
S686 ..2c1f2
L226/S168 ..2c1f2a
L643 ..2c1f2b
S893 ..2c1f2c
CTS1202.1/L1066.1 ..2c1f2c1
CTS9881 ..2c1f2c1a
DF73/S923 ..2c1f2d
PF825.2 ..2c1f3
DF21/S192 ..2c1g
P314.2/S220.2 ..2c1g1
L362 ..2c1g1a
S280/Z246 ..2c1g2
DF25/S253 ..2c1g2a
DF5/S191, S281/Z248 ..2c1g2a1
L658 ..2c1g2a1a
CTS3655/S3787 ..2c1g2a1b
L627 ..2c1g2a1b1
L1402 ..2c1g2a1c
L720/S299 ..2c1g3
S3058 ..2c1g4
S423<, S424, S426, S3025, S3026, S3031, S3057 (See Notes regarding S423) ..2c1g4a
CTS2187/S190, CTS9333/S307, S301, S308, S309, S427, S3027, S3028, S3034 (See Notes regarding S3028) ..2c1g4a1
S425, S3033 ..2c1g4a1a
L130 ..2c1g5
L371/S300 ..2c1h
CTS2501/S836, CTS6581 ..2c1i
L744/S388, L745/S463, L746/S310 ..2c1i1
L563 ..2c1i2
S470 ..2c1j
L555/S393 ..2c1j1
L1335/S530 ..2c1k
CTS6838, CTS7030/S735, CTS11722/L1065/S749 ..2c1k1
L743 ..2c1k1a
CTS4466/S1136 ..2c1l
L270.2 ..2c1l1
CTS2457.2 ..2c1m
L679 ..2c1n
CTS300 ..2c2
CTS6919/S3689 ..2c2a
L238/S182 ..2d
DF19/S232 ..2e
DF88/S4298 ..2e1
L644 ..2e1a
L1199 ..2e1b
L719 ..2e1c
S233/Z302 ..2e2
DF99/S11987 ..2f


Revised: 27 Jul 2016