Contrasting Paternal and Maternal Genetic Histories of Thai and Lao Populations

Abstract

The human demographic history of Mainland Southeast Asia (MSEA) has not been well studied; in particular, there have been very few sequence-based studies of variation in the male-specific portions of the Y chromosome (MSY). Here, we report new MSY sequences of ∼2.3 mB from 914 males and combine these with previous data for a total of 928 MSY sequences belonging to 59 populations from Thailand and Laos who speak languages belonging to three major Mainland Southeast Asia families: Austroasiatic, Tai-Kadai, and Sino-Tibetan. Among the 92 MSY haplogroups, two main MSY lineages (O1b1a1a* [O-M95*] and O2a* [O-M324*]) contribute substantially to the paternal genetic makeup of Thailand and Laos. We also analyze complete mitochondrial DNA genome sequences published previously from the same groups and find contrasting pattern of male and female genetic variation and demographic expansions, especially for the hill tribes, Mon, and some major Thai groups. In particular, we detect an effect of postmarital residence pattern on genetic diversity in patrilocal versus matrilocal groups. Additionally, both male and female demographic expansions were observed during the early Mesolithic (∼10 ka), with two later major male-specific expansions during the Neolithic period (∼4–5 ka) and the Bronze/Iron Age (∼2.0–2.5 ka). These two later expansions are characteristic of the modern Austroasiatic and Tai-Kadai groups, respectively, consistent with recent ancient DNA studies. We simulate MSY data based on three demographic models (continuous migration, demic diffusion, and cultural diffusion) of major Thai groups and find different results from mitochondrial DNA simulations, supporting contrasting male and female genetic histories.

The paternal and maternal genetic history of Vietnamese populations

“…Second, there has been limited recent contact between some groups, leading to some haplotype sharing. The levels of genetic differentiation among groups of 10% based on mtDNA and 23% based on the MSY (Table 1) are similar to what was found previously for populations from Northwestern Amazonia (13% mtDNA and 27% MSY; [29]) and higher than those found for Thai populations (8.5% mtDNA and 11% MSY; [45]). We also found particularly low levels of diversity in some specific groups, like the Mang and Sila (Fig.…”

“…Considering the difference in mutation rates for the different molecules [37,39], a new mutation is expected in an MSY haplotype of our target size every 489.4 years, and in the whole mtDNA genome every 3624 years; thus, new mutations erase MSY sharing faster than mtDNA sharing. The proportion of MSY haplotypes that are shared within Vietnamese populations (24.2%) is much higher than observed in previous studies of the same MSY regions in other populations (7.1% for Thai/Lao populations [45], 13.7% for northwest Amazonian populations [29], and 6.9% for Angolan populations [46] ( Supplementary Material Fig. S7).…”

Cultural variation impacts paternal and maternal genetic lineages of the Hmong-Mien and Sino-Tibetan groups from Thailand

“… There are 14 populations sampled in the present study from northern Thailand (HM1–HM5, Y1–Y2, KSK3, MR, MR, LS and SH2) and northeastern Thailand (PT2 and IS5), together with 59 Thai/Lao populations sampled in previous studies [ 12 – 15 ]. Red stars, green triangles, black circles, and blue squares represent Hmong-Mien, Sino-Tibetan, Austroasiatic, and Tai-Kadai speaking populations, respectively.…”

“…In particular, postmarital residence pattern varies among the hill tribes, with some practicing patrilocality (i.e., following marriage, the woman moves to the residence of the man) while others are matrilocal (i.e., the man moves to the residence of the woman). The first study to document an effect of patrilocality vs. matrilocality on patterns of human mitochondrial (mt) DNA vs. male-specific portion of the Y chromosome (MSY) variation was carried out on the hill tribes [ 11 ], and has been further investigated in subsequent studies [ 9 , 12 ].…”

“…Our previous studies on the paternal and maternal genetic lineages and structure of many TK and AA groups indicated different and complex demographic histories in populations from Thailand and Laos [ 12 – 15 ]. However, the ST and HM speaking groups have not been studied in as much detail.…”