Genetic Structure of Tibeto-Burman Populations of Bangladesh: Evaluating the Gene Flow along the Sides of Bay-of-Bengal

Abstract

Human settlement and migrations along sides of Bay-of-Bengal have played a vital role in shaping the genetic landscape of Bangladesh, Eastern India and Southeast Asia. Bangladesh and Northeast India form the vital land bridge between the South and Southeast Asia. To reconstruct the population history of this region and to see whether this diverse region geographically acted as a corridor or barrier for human interaction between South Asia and Southeast Asia, we, for the first time analyzed high resolution uniparental (mtDNA and Y chromosome) and biparental autosomal genetic markers among aboriginal Bangladesh tribes currently speaking Tibeto-Burman language. All the three studied populations; Chakma, Marma and Tripura from Bangladesh showed strikingly high homogeneity among themselves and strong affinities to Northeast Indian Tibeto-Burman groups. However, they show substantially higher molecular diversity than Northeast Indian populations. Unlike Austroasiatic (Munda) speakers of India, we observed equal role of both males and females in shaping the Tibeto-Burman expansion in Southern Asia. Moreover, it is noteworthy that in admixture proportion, TB populations of Bangladesh carry substantially higher mainland Indian ancestry component than Northeast Indian Tibeto-Burmans. Largely similar expansion ages of two major paternal haplogroups (O2a and O3a3c), suggested that they arose before the differentiation of any language group and approximately at the same time. Contrary to the scenario proposed for colonization of Northeast India as male founder effect that occurred within the past 4,000 years, we suggest a significantly deep colonization of this region. Overall, our extensive analysis revealed that the population history of South Asian Tibeto-Burman speakers is more complex than it was suggested before.

An anatomical study of wormian bones from the eastern part of India: is genetic influence a primary determinant of their morphogenesis?

“…Demographic studies have documented crossovers between these two geographically close population groups (Gazi et al 2013), which could possibly be reflected in the findings of the present study, where we observed an incidence of 21.21 % of Inca bone in skulls of a population from Eastern India (Figs. 2, 3), which is significantly higher than the incidence reported from other regions of India, as well as most of the other population groups of the world (Singh et al 1979;Marathe et al 2010;Berry and Berry 1967).…”

Mitochondrial DNA Control Region Variation from Bangladesh: Sequence Analysis for the Establishment of a Forensic Database

“…mtDNA control regions sequence of this population showed lower sequence diversity 0.8475 ± 0.0134, than the tribal Indian-specific diversity 0.989 (95% CI: 0.975, 0.969) indicating gene flow shares with East and Southeast Asian specific diversity than Indian diversity [19]. The random match probability is 8.09% with 43 substitutions.…”

“…In fact, a precise haplogroup classification is an issue of increasing importance when mtDNA analysis is applied to forensic casework. The distributions of mtDNA haplogroups in mainstream population of Bangladesh are less complex than those of the tribal populations of Chittagong Hill-Tracts [19] and West Bengal of India [20]. The low sequence diversity of mainstream Bangladeshi population indicated that this population are distinct than those of Thailand, Myanmar, and Northeast India.…”

Evaluating the genetic impact of South and Southeast Asia on the peopling of Bangladesh

“…1). All structure runs performed 40,000 iterations after a burn-in of 50,000, following the admixture model and sample group information method described elsewhere [5].…”

“…The populations of Bangladesh constitute mostly Bengali speakers (a branch of Indo-Aryan language), while the remaining are tribal groups affiliated with Dravidian, Indo-European, Austroasiatic and Tibeto-Burman language families [1][2][3]. The number of genetic studies of this region is very limited and mainly restricted to forensic markers for a few caste and tribal populations [4][5][6][7][8]. Several of the tribes are yet to be investigated and none of the study however, so far have analysed a large number of tribal and caste populations.…”