Shared paternal ancestry of Han, Tai-Kadai-speaking, and Austronesian-speaking populations as revealed by the high resolution phylogeny of O1a-M119 and distribution of its sub-lineages within China.

OBJECTIVES: The aim of this research was to explore the origin, diversification, and demographic history of O1a-M119 over the past 10,000 years, as well as its role during the formation of East Asian and Southeast Asian populations, particularly the Han, Tai-Kadai-speaking, and Austronesian-speaking populations. MATERIALS AND METHODS: Y-chromosome sequences (n = 141) of the O1a-M119 lineage, including 17 newly generated in this study, were used to reconstruct a revised phylogenetic tree with age estimates, and identify sub-lineages. The geographic distribution of 12 O1a-M119 sub-lineages was summarized, based on 7325 O1a-M119 individuals identified among 60,009 Chinese males. RESULTS: A revised phylogenetic tree, age estimation, and distribution maps indicated continuous expansion of haplogroup O1a-M119 over the past 10,000 years, and differences in demographic history across geographic regions. We propose several sub-lineages of O1a-M119 as founding paternal lineages of Han, Tai-Kadai-speaking, and Austronesian-speaking populations. The sharing of several young O1a-M119 sub-lineages with expansion times less than 6000 years between these three population groups supports a partial common ancestry for them in the Neolithic Age; however, the paternal genetic divergence pattern is much more complex than previous hypotheses based on ethnology, archeology, and linguistics. DISCUSSION: Our analyses contribute to a better understanding of the demographic history of O1a-M119 sub-lineages over the past 10,000 years during the emergence of Han, Austronesians, Tai-Kadai-speaking populations. The data described in this study will assist in understanding of the history of Han, Tai-Kadai-speaking, and Austronesian-speaking populations from ethnology, archeology, and linguistic perspectives in the future.

Paternal gene pool of Malays in Southeast Asia and its applications for the early expansion of Austronesians.

OBJECTIVES: The origin and differentiation of Austronesian populations and their languages have long fascinated linguists, archeologists, and geneticists. However, the founding process of Austronesians and when they separated from their close relatives, such as the Daic and Austro-Asiatic populations in the mainland of Asia, remain unclear. In this study, we explored the paternal origin of Malays in Southeast Asia and the early differentiation of Austronesians. MATERIALS AND METHODS: We generated whole Y-chromosome sequences of 50 Malays and co-analyzed 200 sequences from other Austronesians and related populations. We generated a revised phylogenetic tree with time estimation. RESULTS: We identified six founding paternal lineages among the studied Malays samples. These founding lineages showed a surprisingly coincident expansion age at 5000 to 6000 years ago. We also found numerous mostly close related samples of the founding lineages of Malays among populations from Mainland of Asia. CONCLUSION: Our analyses provided a refined phylogenetic resolution for the dominant paternal lineages of Austronesians found by previous studies. We suggested that the co-expansion of numerous founding paternal lineages corresponds to the initial differentiation of the most recent common ancestor of modern Austronesians. The splitting time and divergence pattern in perspective of paternal Y-chromosome evidence are highly consistent with the previous theories of ethnologists, linguists, and archeologists.

[Research progress on genetic and molecular mechanisms of hybrid segregation distortion].

Segregation distortion (SD) is defined as abnormal segregation ratio of hybrid offsprings at some genetic loci deviating from the Mendelian ratio. SD results from the incompatibility among genes from different parents, which could be due to loss-of-function or gain-of-function gene interactions. The mechanism for loss-of-function SD is relatively simple: defective gene combination leads to loss of the original function and eventual cell death. The gain-of-function hybrid SD system is a multi-gene genetic system, comprising two basic components: the killer and the protector. Additional modifiers, such as enhancers and repressors, are also involved. There is a general genetic model for gain-of-function hybrid SD: haplotypes with transmission advantage possess high-activity killer⁺ and protector⁺; those with transmission disadvantage possess low-activity killer- and protector-; neutral haplotypes (wide compatibility types) possess killer- and protector⁺. Depending upon close linkage between the killer and the protector and the accumulation of modifiers, the SD system survived through natural selection. Although the genetic mechanisms are highly similar, different gain-of-function hybrid SD systems have distinctive molecular mechanisms. In this review, we summarize the genetic and molecular mechanisms of hybrid SD, and the relationship between hybrid SD and hybrid sterility.