Haplogroup K2a (Y-DNA)
Haplogroup K2a (M2308, Z4842) is a human Y-chromosome DNA haplogroup. K2a is a primary subclade of haplogroup K2 (M526), which in turn is a primary descendant of haplogroup K (M9). Its sole primary descendant is haplogroup K-M2313 (M2313, Z4858 S11799).
|Possible time of origin||approximately 47,000 years BP.   (Based on the immediate ancestor K2 originating 47,000–55,000 BP, and the secondary descendant NO approximately 38,000 to 47,000 BP.)|
|Possible place of origin||Eurasia|
|Descendants||Confirmed primary descendant: K-M2313 (M2313);|
Confirmed secondary descendant:
|Defining mutations||M2308, Z4842|
A secondary subclade, Haplogroup NO (M214/Page39/PAGES00039), which is a primary subclade of K-M2313, includes a majority of males now living in all parts of East Asia, Northern Eurasia and South East Asia.
Basal K2a-M2308* has been found only in the remains of two Upper Paleolithic individuals, known as "Ust'-Ishim man and "Oase-1", from Siberia and the Balkans respectively. K-M2313* has been documented in two living individuals, who have ethnic ties to South Asia and South East Asia respectively: a Telugu from India and an ethnic Malay from Singapore. In addition, K-Y28299, which appears to be a primary branch of K-M2313, has been found in three living individuals from India. NO-M214* has not been identified in living individuals or remains.
Discoveries since 2016Edit
Before 2016, many authorities considered that the SNP M2308 was always found in conjunction with SNPs such as M2313 and M214. However, researchers such as G. David Poznik discovered examples of Y-DNA that had some, but not all, of the SNPs associated with peculiar to NO (M214), but also lacked SNPs identifying other primary subclades of K2 (M526). Poznik et al. 2016 therefore identified K2a (M2308), K-M2313 and NO (M214) as "parent", "child" and "grandchild" clades respectively. While Poznik used the name "K2a1" for K-M2313, this has not been widely adopted (possibly because K2a1 has also been as an alternate name for less-closely related haplogroups). Poznik et al. also found that K-Y28301 – which has living members in India – is descended from K-M2313. The above findings by Poznik et al. were reiterated by the work of Moreno-Mayar et al. in 2018.
As of 2018, authorities like the International Society of Genetic Genealogy (ISOGG) and YFull (Y-Chromosome Sequence Interpretation Service) have not integrated the discoveries of Poznik et al., and differ from each other in nomenclature.
- ISOGG has continued to use the names "K2a" and "NO" in reference to an undifferentiated clade combining K2a (M2308) and K-M2313 (i.e. Poznik's K2a and "K2a1"), while referring to NO-M214 as "NO1".
- YFull does not distinguish between K-M2308 (K2a) and K-M2313, referring to both as "K-M2335".
There is evidence of at least two additional primary branches within K-M2308 (Poznik: K2a) and/or K-M2313 (Poznik: K2a1).
- YFull alone lists a clade, known only as K-Y28299, branching from an undifferentiated K-M2308/K-M2313 (YFull name: K-M2335). In addition, a newer, more divergent subclade named K-Y28301 is a primary branch of K-Y28299, according to YFull. Furthermore, according to both Poznik and Moreno-Mayar, K-Y28301 is also descended from K-M2313, suggesting the following lineage: K-M2313 > K-Y28299 > K-Y28301. Three living individuals in India have been found to carry K-Y28299* or K-Y28301. (As of 2018, ISOGG had not incorporated K-Y28299 or K-Y28301.)
- ISOGG alone lists a haplogroup known only as "NO1~" [sic] identified by the SNP CTS707/M2306, as a sibling of NO-M214. (Under the taxonomic conventions used by ISOGG, a tilde [~] indicates a distinct haplogroup, the position of which in the phylogeny is as yet unclear.) NO1~ is likely a primary branch of either K-M2313 or NO-M214, because, as of 2018, YFull regards CTS707/M2306 as synonymous with M214/PAGE39/PAGES00039, and yet NO1~ is also not (according to ISOGG) ancestral to either Haplogroup N (M231) or Haplogroup O (M175).
K2a K-M2308 
- K-M2313 (Z4952/M2339/E482, F549/M2335/S22380/V4208,[Note 1] CTS11667, Z4842/M2308/V1371, F650/M2346,
- Notes regarding phylogenetic tree
- Some authorities, such as ISOGG and YFull, do not yet include the separation of the subclade defined by the SNP F549/M2335/S22380/V4208 from the clade defined by the SNPs M2308 and Z4842, identified by Poznik et al. (2016).
- Position of K-Y28299 and its subclade K-Y28301 based on YFull 2018. In addition, while K-Y28299 is not specifically mentioned by researchers such as Poznik et al. (2016) and Moreno-Mayar et al. (2018), these sources do state that K-Y28301 is a lineal descendant of K-M2313.
- No phylogenetic name as of 2018; according to YFull, K-Y28301 is a primary branch of K-Y28299. In addition, according to Poznik et al. 2016 and Moreno-Mayar et al. 2018, K-Y28301 is a descendant of K-M2313.
- ISOGG 2018 name NO1.
- "NO1~" is a temporary name used by ISOGG (2018). Approximate position only; YFull (2018) regards CTS707/M2306 as concurrent with M214/Page39, suggesting that NO1~ is a primary branch of K-M2313 or NO-M214.
K2a* has been found only in the paleolithic remains mentioned above:
- "Ust'-Ishim man" – the name given to 45,000 year old remains of one of the early modern humans to inhabit western Siberia. The fossil was named after the Ust'-Ishim District of Siberia where it had been discovered. Until 2016, Ust'-Ishim man was classified as belonging to Haplogroup K2*.
- "Oase-1", the remains of an individual who lived approximately 37,800 years ago, in Eastern Europe (modern Romania).
Basal examples of haplogroup NO* have not been identified.
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K-Y28299(xY28301) has been found in a living male from India.
- YFull Haplogroup YTree v5.06 at 25 September 2017
- Karmin, Monika; Saag, Lauri; Vicente, Mário; et al. (2015). "", "A recent bottleneck of Y chromosome diversity coincides with a global change in culture". Genome Research. 25 (4): 459–466. doi:10.1101/gr.186684.114. PMC 4381518. PMID 25770088.
- G. David Poznik et al., 2016, "Punctuated bursts in human male demography inferred from 1,244 worldwide Y-chromosome sequences" Nature Genetics, no. 48, pp. 593–599.
- Karafet et al. 2014
- Genetic Homeland, 2018, DNA Marker Index Chromosome Y M2308 (6 March 2018).
- Genetic Homeland, 2018, DNA Marker Index Chromosome Y M2313 (6 March 2018).
- YFull YTree v5.08, 2017, "K-M2335" (9 December 2017); PhyloTree, 2017, "Details of the Y-SNP markers included in the minimal Y tree" (9 December 2017); GeneticHomeland.com, 2016, DNA Marker Index Chromosome Y V4208 (9 December 2017).
- Moreno-Mayar JV, Vinner L, de Barros Damgaard P, de la Fuente C, Chan J, Spence JP, Allentoft ME, Vimala T, Racimo F, Pinotti T, Rasmussen S, Margaryan A, Iraeta Orbegozo M, Mylopotamitaki D, Wooller M, Bataille C, Becerra-Valdivia L, Chivall D, Comeskey D, Devièse T, Grayson DK, George L, Harry H, Alexandersen V, Primeau C, Erlandson J, Rodrigues-Carvalho C, Reis S, Bastos MQR, Cybulski J, Vullo C, Morello F, Vilar M, Wells S, Gregersen K, Hansen KL, Lynnerup N, Mirazón Lahr M, Kjær K, Strauss A, Alfonso-Durruty M, Salas A, Schroeder H, Higham T, Malhi RS, Rasic JT, Souza L, Santos FR, Malaspinas AS, Sikora M, Nielsen R, Song YS, Meltzer DJ, Willerslev E., "Early human dispersals within the Americas", Science, 2018 vol. 362, no. 6419 (December 7).
- ISOGG, Y-DNA Haplogroup Tree 2018 (17 January 2018).
- YFull YTree v5.08, 2017, "K-M2335" (9 December 2017)
- YFull YTree v5.08, 2017, "K-M2335" (9 December 2017)
- PhyloTree, 2017, "Details of the Y-SNP markers included in the minimal Y tree" (9 December 2017)
- GeneticHomeland.com, 2016, DNA Marker Index Chromosome Y V4208 (9 December 2017).
- Callaway, Ewen & Nature magazine (23 October 2014). "45,000-Year-Old Man's Genome Sequenced". Scientific American. Retrieved 24 October 2014.