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). As of 2020, K-M2313 is known to have two primary subclades: Haplogroup NO (M214/Page39/PAGES00039), which has numerous members and the extremely rare K-Y28299. Basal, undivergent K2a* (K-M2308*) has been found only in the remains of two Upper Paleolithic individuals, known as "Ust'-Ishim man and "Oase-1", who lived in Siberia  and the Banat region of south-central Europe, respectively, about 37–45 ky BP. No examples of K-M2313* or NO* (NO-M214*) have been identified in living males or remains. However, subclades of NO-M214 include a majority of living males in East Asia, Northern Eurasia and South East Asia. K-Y28299 has been found in three living individuals from India. Another two other living males, who have been documented as belonging to K-M2313(xM214), have not been tested for Y28299 (and therefore may belong to K-Y28299 ). These K-M2313(xM214) individuals have ethnic ties to South Asia and South  East Asia respectively: a Telugu from India and an ethnic Malay from Singapore. Discoveries since 2016. 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 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 sometimes been used as an alternate name for other, 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. There is  evidence of at least two additional primary branches within K-M2308 (Poznik: K2a) and/or K-M2313 (Poznik: K2a1). Phylogenetic tree. K2a "K-M2308"           ? "NO1~" (CTS707/M2306)  Distribution. K2a* (K-M2308*). K2a* has been found only in the paleolithic remains mentioned above: K-M2313. As of 2016, two living males had been found to carry K-M2313(xNO-M214) – a British Asian who identifies as Telugu and an ethnic Malay sampled in Singapore. Note that they were NOT tested for Y28299. NO (M214). Basal examples of haplogroup NO* have not been identified. Subclades of haplogroup NO include a majority of living males  in East Asia, South East Asia and northern Eurasia. K-Y28299*. K-Y28299(xY28301) has been found in a living male from India. K-Y28301, a subclade of K-Y28299, has been found in living individuals with their origins in Andhra Pradesh and Arunachal Pradesh India.