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Fig. 6 | Genome Biology

Fig. 6

From: Differentiated demographic histories and local adaptations between Sherpas and Tibetans

Fig. 6

A proposed model of demographic history of SHP and TBN. A simplified model for the origins and evolutionary history of Tibetans and Sherpas based on the observations and estimations from this study. GF gene flow, MRCA most recent common ancestor. Dashed lines indicate gene flow events and arrows denote directions. MRCA1, MRCA2, and MRCA3 are based on Fig. 5b. We inferred GF1 from the treemix results (Additional file 1: Figures S31 and S32) and the observation that both SHP (mainly for Chinese Sherpa) and TBN contain an East Asian genetic component (EAC) (Fig. 3). GF2 was based on the excess EAC in TBN compared to SHP (Fig. 3; Additional file 1: Figure S27). Based on the f 3 tests (Fig. 4b; Additional file 1: Figure S22) and the higher proportion of EAC in Kham and Amdo Tibetans (Fig. 3), we confirmed GF3. GF4 is based on Fig. 4b and Additional file 1: Figure S23 and the historical record that Sherpas migrated from the Kham region in eastern Tibet to Nepal within the last 300–400 years, possibly supporting the genetic contact between Khumbu Sherpas and Kham Tibetans. GF5 is based on the excess Sherpa genetic component in Ü-Tsang Tibetans compared to that in Kham and Amdo Tibetans (Fig. 3) and also on the results shown in Additional file 1: Figure S26. GF6 is based on Fig. 4a. The higher South Asian component in Chinese Sherpas compared to that in Nepalese Sherpas (Fig. 3) and the f 3 statistics (Fig. 4a) validated the presence of GF7. Population substructures in both SHP and TBN are based on PCA (Fig. 2), ADMIXTURE (Fig. 3), F ST (Additional file 1: Figures S4 and S5), outgroup f 3 tests (Additional file 1: Figures S8–S10), and D statistics (Additional file 1: Figures S28–S30). Estimates of MRCA1, MRCA2, and MRCA3 are based on Fig. 5b and Additional file 1: S34

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