Mitochondrial genomics identifies major haplogroups in Aboriginal Australians

Area of Science:

• Genetics
• Anthropology
• Bioinformatics

Background:

• Mitochondrial DNA (mtDNA) analysis is crucial for understanding human population history and migration patterns.
• Previous studies have identified broad macrohaplogroups (M and N) in Australian Aboriginal populations, but finer haplogroup diversity remains incompletely characterized.

Purpose of the Study:

• To classify genetic diversity within Aboriginal Australian populations using complete and partial mitochondrial genome sequences.
• To identify and characterize distinct mitochondrial DNA haplogroups and their geographical distributions within Australia.
• To investigate deep ancestral connections and estimate the time depth of the founding population in Australia.

Main Methods:

• Sequencing of eight new complete and 41 partial mitochondrial genomes from Aboriginal Australians.
• Classification of sequences into five haplogroups (AuA-AuE) based on established global lineages (M and N).
• Comparative analysis with existing mitochondrial genome data from Australia and surrounding regions (Papua New Guinea, Malaya, Andaman and Nicobar Islands).
• Coalescence analysis of coding regions to estimate time depth.

Main Results:

• Five distinct haplogroups (AuA, AuB, AuC, AuD, AuE) were identified, with AuB belonging to macrohaplogroup M and AuA, AuC, AuD, AuE to macrohaplogroup N.
• Specific subdivisions within macrohaplogroup N were assigned: AuA to S, AuD to O, AuC to P4, and AuE to P8.
• Geographical distribution: AuA and AuB are widespread; AuC is found in western New South Wales and northern Australia; AuD and AuE are primarily in central Australia.
• Deep ancestral connections were observed at the macrohaplogroup level (M and N) between Australia and surrounding regions.
• Genetic isolation within Australia appears to be significant, with deeper ancestral connections than indicated by linguistic or cultural affinities.
• Coalescence analysis estimates a time depth supporting the presence of a founding population by 40,000 years ago.

Conclusions:

• The identified haplogroup diversity and distribution indicate significant genetic isolation and long-term continuity within Aboriginal Australian populations.
• Ancestral connections within Australia are ancient, predating established linguistic and cultural affiliations.
• The findings support the presence of a founding population in Australia at least 40,000 years ago, contributing to the deep genetic heritage of Aboriginal Australians.