STR Identification

Those who closely match the key off-modal Rox2 'signature' STR markers over 111 markers and take SNP tests consistently find they are also positive for Rox2 SNPs when they test for them.  With the recent increase in affordable NGS (Next Generation Sequencing) technology, like FTDNA's Big Y, a Rox2 match can now be identified with one test and then be placed in the appropriate branch of the phylogenetic tree (a family tree for ySNP results).  Rox2 formed many centuries before the final fixing of surnames (up to around the fifteenth century in some areas) and as a consequence there are many different surnames represented in Rox2 today.

As the bar chart here illustrates, plotting 67 marker Rox2 matches' genetic distances from the modal/base haplotype produced a clear bell curve.  This indicates that the off-modal STR markers work well in identifying common descent from a founder, even without further SNP confirmation.  Rox2 is a monophyletic clade.  If it were not there would be no smoothly curved bell shape.  The marker order, below, is from FTDNA's 111 STR test.  Note: the numbers in brackets are the average number of repeats across the database for P312 men at those particular markers, e.g.  DYS389ii=30 (29) means Rox2 generally have an average of 30 (in bold type) repeats at that marker but the wider P312 modal is 29.

KEY ROX2 OFF-MODAL STRs, 1 - 67 MARKERS:    DYS391=10 (P312 modal=11)    DYS389ii=30 (29)    DYS449=30 (29)    DYS607=14 (15)    DYS534=14 (15). 

KEY ROX2 OFF-MODAL STRs, 68 - 111  MARKERS: 540=13 (12), 717=20 (19), 589=11 (12), 636=11 (12), 532=14 (13), 504=16 (17).

An early and important defining STR marker, mentioned above, was found to be DYS717=20.  It is included in the 111 marker upgrade.  DYS717 is strongly off-modal in Rox2 and is considered a stable, slow mutating marker.  For reference, R1b modal is DYS717=19, L21+ 'Scots Modal' is 717=21. 

Less uniform signature off-modal markers in the 68-111 panels: DYS712 <=20 (21), DYS714 >=26 (25).

It is not unusual for a Rox2 STR match to mismatch on some of the off-modal signature markers mentioned above but the majority remain consistent.  GD (genetic distance) forms a bell curve, some haplotypes are outliers that have mutated very little, some a lot, but most are in the middle of the bell curve.  That is where the majority of kits find themselves - the average GD.  

The threshold for a STR match to show up at FTDNA is currently GD 7 at 67 markers and GD 10 at 111.  Therefore we do not see every one of our Rox2 matches in our individual Matches list because some matches exceed those low genetic distances.  The average FTDNA Rox2 kit will have lots of matches but some will not be visible on the Results pages on your Dashboard.

A prediction of Rox2 for a matching STR haplotype does not depend on simply comparing genetic distance from existing SNP-tested Rox2 kits - the signature off-modal markers mentioned above are crucial in the analysis.  Experience and familiarity with the signature modal haplotypes reduces the risk of mistakes.  I learned STR analysis from others and by trial and error in a long learning curve between 2005 and 2012, a time when no SNPs below R1b-P312 were known for Rox2.  111 STRs have continued to be an invaluable tool in the understanding of Rox2 and help with the age estimate for the haplogroup as a whole.

STR analysis indicated that an early branch could exist in the Swedish Rox2 subclade BY21590 - one that was not then-apparent in the SNP-based phylogenetic trees (2019).  This was confirmed by the formation of BY43192 in the FTDNA Block Tree, March 2020.  Off-modal STR patterns can endure for a very long time in a lineage, c. 1300 years in  the case of the FT171815 branch - it still has a strong off-modal family STR pattern.  Again, relatedness was later confirmed with Big Y testing in late-2019. 

Results used in the TMRCA estimates on this site are of a minimum resolution of 111 STR markers.  Matches can occasionally happen between unrelated R1b haplotypes simply through coincidence (convergence) at low resolution, i.e. 67 STR markers or less.  A 111 marker haplotype can have significantly higher than normal genetic distance (GD) from the Rox2 average and still be identifiable as a Rox2 match using signature markers.  So far every Rox2 match thus far identified with signature STRs at 111 marker resolution has still been a Rox2 match after a Big Y test.  STRs have helped to highlight incorrect SNP results for a Rox2 kit in the past.

The convergence of STR results between unrelated haplotypes is due to a demographic 'explosion' of various R1b-P312 lines around 5000 years ago - there was a sudden 'bushy' expansion of prehistoric lineages across mainland Europe early in P312's history.  The unrelated L21>DF13>L1335>L1065 'Scots Modal' cluster has similar key off-modal markers to Rox2 at low resolution.  Until 2008 it was thought there might be some recent relationship between Scots Modal and Rox2 because of a few similar off-modal STR markers but the advent of L21 testing in 2008 revealed that Rox2 was negative for L21.  The STR similarity disappears at a resolution of 67 and 111 markers.  Rox2 has no connection in around 5000 years with the distant ancestor of L21+ 'Scots Modal' or other similar L21+ 'Irish Sea' clusters.  DF27 and L21 belong to two parallel  ancient P312 subclades with different stories and distributions.