|Possible time of origin||47,000-55,000 years BP |
|Possible place of origin||Southeast Asia |
|Descendants||K2a (M2308); K2b (MPS); K2c; K2d; K2e.|
|Defining mutations||rs2033003 (M526)|
Relative to its age, the internal structure of K2 is extremely complex, and subclades of it are carried by males native to regions including Oceania, South East Asia, East Asia, Central Asia, the Americas, Europe, the Horn of Africa and South Asia.
The only living males reported as carrying the basal paragroup K2* (K-M526) are indigenous Australian males. Up to 27% of them may carry K2* and approximately 29% of Aboriginal Australian males belong to subclades of K2b1.
Haplogroup K2 is the direct ancestral haplogroup to five primary clades (as of 2016) and many notable subclades:
- Haplogroup K2a (M2308)
- K2b M1221/P331/PF5911 (previously known as Haplogroup MPS)
- K2c (P261)
- K2d (P402)
- K2e (M147)
At the level of highly-derived subclades, K2 is almost universal in some modern Eurasian and Native American populations. However, the only living males reported to carry the basal paragroup K2* are indigenous Australians. Major studies published in 2014 and 2015 suggest that up to 27% of Aboriginal Australian males carry K-M526* and others carry a subclade of K2: another 27% probably have K2b1a1 (P60, P304, P308; also known as "S-P308") and perhaps 2.0% have Haplogroup M1 – also known as M-M4 (or "M-M186") and K2b1d1.
The descendants of K2b include the major haplogroups M; S, P, Q, and R. These are now numerically in dominant in: Oceania, Central Asia, Siberia, among Native American populations, Europe, and South Asia.
A rapid diversification within and from K2 (M526), most likely in Southeast Asia, is suggested by estimates of the point in time that K2 branched off from K* (M9). Likewise the branching from K2 of K2b (P331) and Haplogroup P (K2b2 P295) from K2b, as well as Haplogroups Q and R from P (K2b2), and their subsequent expansions westward in Europe, and eastward into the Americas.
K2c, K2d, and K2e are extremely rare, minor lineages in specific parts of South and Southeast Asia. K2c (P261) has been reported only among males in Bali and K2d (P402) only in Java. K2e (M147), which has been found in two modern cases from South India, was provisionally named "pre-NO" (among other names), as it was believed initially to be ancestral to K2a (NO). However, it was later found to be a primary branch of Haplogroup K2 (K-M526) and a sibling of K2a; the new clade was renamed K2e.
The name K2 was introduced in 2014, following dissatisfaction with the previous names.
K(xLT), the name introduced by the Y Chromosome Consortium in 2012 to replace MNOPS, was controversial. Under the previous methodology, a term such as "K(xLT)" designated all clades and subclades that belonged to K, but did not belong to Haplogroup LT; the haplogroups subordinate to MNOPS would likely have been renamed "U", "V", "W" and "X", and MNOPS would therefore have become "MNOPSUVWX". This posed a problem, because there was no way to disambiguate between "K(xLT)" in the broad and narrow meanings of the term.
- Karafet et al. 2014
- Chiaroni, Jacques; Underhill, Peter A.; Cavalli-Sforza, Luca L. (2009). "Y chromosome diversity, human expansion, drift, and cultural evolution". PNAS. 106: 20174–9. doi:10.1073/pnas.0910803106. PMC . PMID 19920170.
- Nagle, N. et al., 2015, "Antiquity and diversity of aboriginal Australian Y-chromosomes", American Journal of Physical Anthropology (epub ahead of print version; abstract). (The authors assumed 56% of the samples taken to be non-indigenous.)
- Karafet 2014
- 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.
- Tatiana M. Karafet, Fernando L. Mendez, Herawati Sudoyo, J. Stephen Lansing and Michael F. Hammer; 2015, "Improved phylogenetic resolution and rapid diversification of Y-chromosome haplogroup K-M526 in Southeast Asia", European Journal of Human Genetics, no. 23 (March), pp. 369–73.
|Phylogenetic tree of human Y-chromosome DNA haplogroups [χ 1][χ 2]|
|A00||A0-T [χ 3]|
|A0||A1 [χ 4]|
|I||J||LT [χ 5]||K2|
|L||T [χ 6]||K2a [χ 7]||K2b [χ 8]||K2c||K2d||K2e [χ 9]|
|K2a1||K2b1 [χ 10]||P [χ 11]|
|NO||S [χ 12]||M [χ 13]||P1||P2|