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Thread: FTDNA pedigree-based BigY mutation rate project?

  1. #1
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    FTDNA pedigree-based BigY mutation rate project?

    Does anyone know if there exists any such project at all? I thought it may be interesting to compare (calibrate?) the Y-DNA Warehouse Adamov-based estimates using some real sample data. Im sure with so many people participating it would not be overly difficult to amass a couple hundred pedigrees, even if very simple and spanning only a few generations on average. Perhaps someone has come accross anything interesting?

  2. #2
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    L21>L226>FGC5639

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    I have been considering using my R-L226 chart (with TMRCA estimates) to calculate preliminary mutation rates for Y700 markers and Y111 markers as well. However, with 175 YSNP branches, 285 Big Ys (with almost all now reporting both Y500 and Y700 YSTRs, over 900 Y67 or higher testers, this would be pretty major manual effort. The biggest challenge is determining the time frames between mutations which I am still attempting to create a believable methodology. Here is my current approach:

    1) For YSNP branches with no YSTR mutations, there will be a significant reduction of the time frames involved as all of this part of the chart has no YSTR mutations.
    2) For YSTR mutations between YSNP branches - I will divide the estimated time frame between YSNP branches.
    3) Below terminal YSNP branches, there will be the shared YSTR mutations - I will divide this by half for the remaining time frame.
    4) Below terminal YSNP branches, there will be private YSTR mutations (those unique to individual testers), I divide by half again.

    Below terminal YSNP branches, the ratio of YSTR branches and private YSTRs varies a lot between terminal YSNP branches. Instead of assuming
    a 50/50 split, I could calculate the ratio for each terminal YSNP branch - but this would be very labor intensive. Here is a link to my L226 chart:

    http://www.rcasey.net/DNA/R_L226/Hap...me.pdf#Page=27
    Last edited by RobertCasey; 09-21-2020 at 07:44 PM.

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  4. #3
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    R1b-L21 L513*

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    I have done this analysis for the R1b-L513 subgroup of R1b-L21, using about 425 Big Ys. At the time they were about evenly split between Y500s and Y700s.

    What I found first off was that older branches sitting above a mix of Y500s and Y700s even with only a small percentage of Y700s tended to accumulate Y700 SNPs fairly quickly and so needed to be considered against Y700 mutation rate frequencies. This is perhaps not an unexpected result and the simplest way to consider it is that even Y500s kits have a large number of "FTxxxx" SNPs in the older branches above them and are assumed to be positive for SNPs that were only discovered later. So a Y500 correction for the SNP mutation rates only really needed to be applied in the lower branches that were made of virtually entirely of Y500 tests. That dynamic is probably even more pronounced now that enough time has passed that Y700s should dominate most of the haplotree.

    But that same effect also worked even just with Y700s only, so that older branches of the haplotree effectively gained more SNPs than any single Y700 test would normally find on its own. If the statistical average mutation rate for SNPs found from Y700 testing is about 83 years per SNP, the SNP frequencies in the older branches of the haplotree (say older than about 3000 years or so) tended to be more frequent - in L513 it averaged 75 years/SNP but that will vary slightly across different haplogroups.

    However across the entire haplotree the variation is still quite large - L513's variation in SNP rates across the whole haplogroup was +/- 27% but that figure will also vary between different haplogroups. And of course across a small number of branches or especially within a close time period to present day the variation can be even more extreme - it's not hard to see 3x-4x the number of SNPs on adjoining branches within the past few hundred years, for example.

  5. The Following 4 Users Say Thank You to Dave-V For This Useful Post:

     CillKenny (09-22-2020),  JMcB (09-21-2020),  Roslav (09-22-2020),  TigerMW (09-24-2020)

  6. #4
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    R1b-Z255
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    K1C1B

    Ireland Ireland Leinster Ireland County Tipperary
    Robert, don't you have a few of the recent Viking samples under Z253? Some of them have clear date ranges.

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