High O2* among tribal populations of East and South East India

Porja population is mainly distributed near the hill slopes of Munchingputtu, Anantagiri, and Peddabayalu regions of Visakhapatnam, Andhra Pradesh (AP), India. They migrated from Odisha to the present habitat about 300 years back. Savara population can be seen in Lakaiguda, Mettiguda, Chintalaguda, and Manduguda regions of Srikakulam, AP, India. Savara language is included in the Kol Munda group of Austro-Asiatic language family.

 Y chromosome haplogroup O-M175 is present in 84.79% of the studied population and is significantly important, as it is the most ubiquitous Y lineage in mainland India, China, Malaysia, Indonesia, and Vietnam (Southeast Asian populations)

Haplogroup O

Haplogroup O identified by M175 (5-bp deletion) was found with highest frequency of 84.79%. It possibly originated in East Asia (Karafet et al. 2008) and then migrated to South Asia Pacific. Paternal signature of haplogroup O can be traced at moderate or low frequencies in some parts of Central Asia and Oceania (Cai et al. 2011; Karafet et al. 2001; Underhill et al. 2001 and Deng et al. 2004). Haplogroup O is further divided into three sub-clades which are defined by the presence of O1-MSY 2.2, O2-P31, and O3-M122. Although the most frequent sub-clade observed in the present study was O2a*, it occurs with a frequency of 42.86% in Porja and 41.94% in Savara. O2a lineages are found in Southeast Asian populations of Malaysia, Vietnam, Indonesia, and Southern China (Sengupta et al. 2006).

Haplogroup R

Haplogroup R is characterized by M207 and is further segregated into two sub-clades R1, which is identified by M173 A>C allele, and R2, identified by M124 C>T allele. This haplogroup R1-M173 is estimated to have arisen during the Last Glacial Maximum (LGM) and is likely to be found in Southwestern Asia (Zhao et al. 2009), which is believed to have arisen 27,000 years ago in Asia. In the present study, haplogroup R2 lineage is present in 3.23% and 3.69% of Porja and Savara population respectively.

Haplogroup H

Haplogroup H is identified by M69 T>C allele. It is further divided into two sub-clades H1 which is identified by M52 A>C allele and H2 which is identified by APT G>A allele. Because of the high frequency of the H haplogroup in Indian tribal groups, it is often regarded as the original Indian haplogroup belonging to be the ancient settlers. We found the presence of H1* and H1a* in the present studied samples in low frequencies, about 4.61% and 3.69% respectively. Haplogroup H has also been reported from Central Asia, Western Asia, and Europe (Wells et al. 2001; Regueiro et al. 2006). 

Figure 3 presents the MDS plot based on Y (SNPs) haplogroup frequencies showing that Birja (AA), Juang (AA), Santhal (AA), and Ho (AA) tribes are more closely related to the present studied population groups, viz., Porja and Savara, showing closer genetic affinity between them. Among the two language groups, Austro-Asiatic and Dravidian, all the AA populations show critically closer genetic affinities with Porja and Savara. Yerukula and Chenchu as well as Naikpodgond form different clusters in the multi-dimensional scaling (MDS) (Fig. 1), which is probably due to the absence of O2a haplogroups (Table 1) which is specific to AA linguistic groups.