Reconstructing Indian-Australian phylogenetic link

Abstract

Background: An early dispersal of biologically and behaviorally modern humans from their African origins to Australia, by at least 45 thousand years via southern Asia has been suggested by studies based on morphology, archaeology and genetics. However, mtDNA lineages sampled so far from south Asia, eastern Asia and Australasia show non-overlapping distributions of haplogroups within pan Eurasian M and N macrohaplogroups. Likewise, support from the archaeology is still ambiguous.

Results: In our completely sequenced 966-mitochondrial genomes from 26 relic tribes of India, we have identified seven genomes, which share two synonymous polymorphisms with the M42 haplogroup, which is specific to Australian Aborigines.

Conclusion: Our results showing a shared mtDNA lineage between Indians and Australian Aborigines provides direct genetic evidence of an early colonization of Australia through south Asia, following the "southern route".

Figure 1

Phylogenetic reconstruction of M42 Lineage. The phylogenetic reconstruction was performed using 7 New mtDNA Sequences from India and 6 Australian Aborigines mtDNA sequences from published source [2,25,36]. The sequence region np 16024 to 434 is missing in two (i.e. DQ112754 and DQ112755) published sequences. Suffixes A, C, G, and T indicate transversions, "d" signifies a deletion and a plus sign (+) an insertion; "s" indicates synonymous polymorphisms; recurrent mutations are underlined. The prefix "@" indicates back mutation. The coalescence age estimates calculated as per Kivisild et al [2] are presented in thousand years ago (kya). Variation at hypervariable positions 16184–16193, 16519 and insertion C at 309 and 315 are not shown.