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Haplogroup R (Y-DNA)
In human genetics, Haplogroup R is a Y-chromosome DNA haplogroup, a subgroup of haplogroup P, associated with the M207 mutation.
OriginsIt is believed to have occurred somewhere in Northwest Asia between 30,000 and 35,000 years ago. However, most of the rare forms of Haplogroup R chromosomes, as well as most cases of the closely related Haplogroup Q, are found among populations of Europe, Central Asia, South Asia, Egypt, Australia, Siberia, and Cameroon. "suggests that southern and western Asia might be the source of this haplogroup": The highest levels of R1b1 and R1b3 are found in Europe, where frequencies of 70% or more have been found in populations from Ireland,[1] Spain,[2] and the Netherlands,[2] and where, according to the Genographic Project conducted by the National Geographic Society,[3] R1b originated on the Iberian Peninsula, being the LGM refuge from which the gene spread.[1] However, another study notes low DYS390 diversity in Iberia, suggesting that R1b in this region is in fact the "youngest" in Europe. The study indicates that R1b likely originated in Central Asia (Kazakhstan) and then migrated to Russia. R1b in Russia is significantly more diverse than in Iberia, suggesting increased age.[4] Correspondingly, the underpinning, undifferentiated R complex has been attributed a huge upper paleolithic dispersion. DistributionThe majority of members of haplogroup R belong to the Haplogroup R1, defined by marker M173. R1 is very common throughout Europe and western Eurasia. Its distribution is believed to be associated with the re-settlement of Eurasia following the last glacial maximum. Its main subgroups are R1a (SRY1532) and R1b (M343). One isolated clade (or clades) of Y chromosomes that appear to belong to Haplogroup R1b1* (P25-derived) is found at high frequency among the native populations of northern Cameroon, such as the Kirdi, in west-central Africa, which is believed to reflect a prehistoric back-migration of an ancient proto-Eurasian population into Africa. R1b1 is the most common haplogroup in North Western Europe[5]. Some researchers have reported having also detected Haplogroup T Y-chromosomes at a low frequency among some of these Cameroonian populations, which also suggests a Eurasian affinity.[6]. Some Y-chromosomes that appear to be closely related to the northern Cameroonian R1b1* are found at a substantial frequency among the modern population of Egypt. Many modern populations of northern Cameroon speak Chadic languages, which are classified as an ancient branch of the Afro-Asiatic superfamily of languages; the now extinct language of the Ancient Egyptians also belonged to the same superfamily. Individuals whose Y-chromosomes possess all the mutations on internal nodes of the Y-DNA tree down to and including M207 (which defines Haplogroup R) but which display neither the M173 mutation that defines Haplogroup R1 nor the M124 mutation that defines Haplogroup R2 are categorised as belonging to group R*. Some instances of Haplogroup R* have been reported from samples of Australian aboriginal populations. Haplogroup R* has also been found in 10.3% (10/97) of a sample of Burusho and 6.8% (3/44) of a sample of Kalash from northern Pakistan.[7] SubcladesThe subclades of haplogroup R with their defining mutation, according to the stratification chart published by the 2006 International Society of Genetic Genealogy (ISOGG)[8]:
R*R* is found in both Central and South Asians, including 10.3% (10/97) of Burusho and 6.8% (3/44) of Kalash.[7] Some instances of R* have been reported from samples of Australian aboriginal populations. R1
Distribution of R1a (purple) and R1b (red) R1aThe highest levels of R1a (>50%) are found along the Eurasian Steppe: the Ishkashimi (68%), the Tajik population of Khojant (64%), Kyrgyz (63.5%), Sorbs (63.39%), Poles (56.4%), and Ukrainians (54.0%)[9][10][11][2] and in the extreme north of India among the Kashmiri Pandits (72%).[12] R1a has been variously associated with:
R1a1 provides genetic corroboration of the Kurgan theory of Indo-European origins, and suggests that the Sredny Stog and Yamnaya cultures of the Pontic Steppe region north of the Black Sea in modern day Ukraine were the Proto-Indo-Europeans. R1bHaplogroup R1b originated in Central Asia prior to or during the last glaciation. It is the most common haplogroup in Western Europe and may have survived the LGM concentrated in refugia in southern Europe and the Aegean. It is also present at lower frequencies throughout Eastern Europe, with higher diversity than in western Europe, suggesting an ancient migration of R1b from the east.[4] R1b is also found at various frequencies in many different populations near the Ural mountains and Central Asia, its likely region of origin. It is also found in North Africa where its frequency surpasses 10% in some parts of Algeria[14]. In south-eastern England the frequency of R1b is about 70%; in parts of the rest of north and western England, Spain, Portugal, Wales and Ireland, it is as high as 90%; and in parts of north-western Ireland it reaches 98%. The R1b clade appears to have a much higher degree of internal diversity than R1a, which suggests that the M343 mutation that derives R1b from R1* may have occurred considerably earlier than the SRY1532 mutation that defines R1a. R1b (previously called Hg1 and Eu18) is the most frequent Y-chromosome haplogroup in Europe. It is an offshoot of R1 (M173), characterised by the M343 marker.[15] An overwhelming majority of members of R1b are classified as R1b1 (defined by the P25 marker), the remainder as R1b*. Its frequency is highest in Western Europe (and due to modern European emigration, in parts of the Americas). The majority of R1b-carriers of European descent belong to the subclade R1b1c (M269). R2At least 90% of R2 individuals are located in the Indian sub-continent.[16] It is also reported in Caucasian and Central Asian populations. R2 (M124) arose about 25,000 years ago in southern Central Asia, and its members migrated southward as part of the second[17] major wave of human migration into India.[18] The presence of R2 almost exclusively in India could also mean that the differentiation of R into R1 and R2 happened in Central India or Western India. NotesReferences
See also
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ca:Haplogrup R del cromosoma Y humà cs:Haploskupina R (Y-DNA) de:Haplogruppe R (Y-DNA) fr:Haplogroupe R (Y-ADN) it:Aplogruppo R (Y-DNA) ru:??????????? R Source: Wikipedia | The above article is available under the GNU FDL. | Edit this article
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