In May of 2003 I did a small survey of how many men had matches (or near matches) to their 25 marker haplotypes to men with a different surname as reported in the database of Family Tree DNA customers. I sent out the survey to men listed in the Ybase.org database as having a 25 marker Y-chromosome haplotype resembling that of the modal sequence for the haplogroup R1b. The information below is the summation of the 68 replies I received.
The graph above shows the percentage of men who had found different surname matches (two mutational steps or less) categorized according to how far away they were from the modal sequence for R1b. It can be seen that all those nearest the R1b modal sequence had found different surname matches. This percentage is seen to drop as the haplotypes diverged farther from the R1b modal sequence. This probably means that there is a trend for the haplotypes in the neighborhood of the modal R1b sequence to be more common than haplotypes farther away from that sequence.
The second graph shows the average number of different surname matches found categorized according to the differences from the modal R1b sequence. This average is taken over the total population in that category - both those who found matches and those who didn't.
There are a couple of sources of inaccuracy built into these numbers. Some people had haplotypes that were near the modal haplotype of other surname studies - leading to inflated values for the number of matches. Other people may have been unaware that the surname study to which they belonged to was set to "Private" - causing them to mistakenly report finding no different surname matches.
Something interesting to note is that there was one haplotype ( French #1004), with a four marker mismatch from the modal R1b sequence, that reported more matches than the haplotype just one step from the modal R1b. It turned out that these matches were spread out over 15 different surnames - so this haplotype apparently does have an unusually high frequency of occurrence. This probably means that there are several other R1b haplotypes besides the modal R1b sequence that have high frequencies of occurrence - this study was small enough that it only happened upon one of them. It would be interesting to look for more of these clusters, and to see whether or not they have any special geographic distribution.
