title: Understanding influences of culture and history on mtDNA variation and population structure in three populations from Assam, Northeast India.
abstract: OBJECTIVE
  Positioned at the nexus of India, China, and Southeast Asia, Northeast India is presumed to have served as a channel for land-based human migration since the Upper Pleistocene. Assam is the largest state in the Northeast. We characterized the genetic background of three populations and examined the ways in which their population histories and cultural practices have influenced levels of intrasample and intersample variation.
  
  
  METHODS
  We examined sequence data from the mtDNA hypervariable control region and selected diagnostic mutations from the coding region in 128 individuals from three ethnic groups currently living in Assam: two Scheduled tribes (Sonowal Kachari and Rabha), and the non-Scheduled Tai Ahom.
  
  
  RESULTS
  The populations of Assam sampled here express mtDNA lineages indicative of South Asian, Southeast Asian, and East Asian ancestry. We discovered two completely novel haplogroups in Assam that accounted for 6.2% of the lineages in our sample. We also identified a new subhaplogroup of M9a that is prevalent in the Sonowal Kachari of Assam (19.1%), but not present in neighboring Arunachal Pradesh, indicating substantial regional population structuring. Employing a large comparative dataset into a series of multidimensional scaling (MDS) analyses, we saw the Rabha cluster with populations sampled from Yunnan Province, indicating that the historical matrilineality of the Rabha has maintained lineages from Southern China.
  
  
  CONCLUSIONS
  Assam has undergone multiple colonization events in the time since the initial peopling event, with populations from Southern China and Southeast Asia having the greatest influence on maternal lineages in the region.
authors.affiliation: Department of Anthropology, University of Florida, Gainesville, Florida, 32611.|Genetics Institute, University of Florida, Gainesville, Florida, 32610.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Rej
authors.affiliation: Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267.
authors.forename: Ranjan
authors.initials: R
authors.lastname: Deka
authors.affiliation: Department of Anthropology, University of Cincinnati, Ohio, 45221.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Norton
mesh_terms: D004272:DNA, Mitochondrial / Q000235:genetics; D005006:Ethnicity / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D006239:Haplotypes; D006801:Humans; D007194:India
chemical_list: D004272:DNA, Mitochondrial
keywords: descent systems; genetic structure; migration; mitochondrial DNA