"R1b", "R1b1", and so on are "phylogenetic" or family tree based names which explain the branching of the family tree of R1b. For example R1b1a and R1b1b would be branches of R1b1, descending from a common ancestor. This means that these names can change with new discoveries.
The alternative way of naming haplogroups is to refer to the SNP mutations used to define and identify them, for example "R-M343" which is equivalent to "R1b." Haplogroup R1b is in other words now identified by the presence of the single-nucleotide polymorphism (SNP) mutation M343, which was discovered in 2004. From 2002 to 2005, R1b was defined by the presence of the SNP named P25.
Standardized naming as described above, both using phylogenetic or mutational systems, was first proposed in 2002 by the Y Chromosome Consortium. Prior to 2002, today's Haplogroup R1b had a number of names in differing nomenclature systems, such as Hg1 and Eu18.Further information: Conversion table for Y chromosome haplogroups
After 2002, a major update of the YCC phylogenetic nomenclature was made in 2008 by Karafet et al. which took account of newer discoveries of branches which could be clearly defined by SNP mutations, including some which changed the understanding of R1b's family tree. Since 2008 it has become increasing necessary to refer to the frequently updated listing made on the ISOGG website.
Also prior to 2002, major Y DNA signatures based on markers other than SNPs were recognized. In Western Europe the STR haplotype known as the Atlantic Modal Haplotype was found to be most common by Wilson et al. Even earlier research using RFLP genotyping identified two distinct haplotypes within R-M269. In southeast Europe and southwest Asia (e.g. the Balkans, Georgia and Turkey) "haplotype 35" or "ht35" was found to be a common form of R-M269, whereas in western Europe "haplotype 15" or "ht15" dominated in frequency.
Read more about this topic: Haplogroup R1b (Y-DNA)
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