Geographic variation in human mitochondrial DNA from Papua New Guinea

High resolution mitochondrial DNA (mtDNA) restriction maps, consisting of an average of 370 sites per mtDNA map, were constructed for 119 people from 25 localities in Papua New Guinea (PNG). Comparison of these PNG restriction maps to published maps from Australian, Caucasian, Asian and African mtDNAs reveals that PNG has the lowest amount of mtDNA variation, and that PNG mtDNA lineages originated from Southeast Asia. The statistical significance of geographic structuring of populations with respect to mtDNA was assessed by comparing observed GST values to a distribution of GST values generated by random resampling of the data. These analyses show that there is significant structuring of mtDNA variation among worldwide populations, between highland and coastal PNG populations, and even between two highland PNG populations located approximately 200 km apart. However, coastal PNG populations are essentially panmictic, despite being spread over several hundred kilometers. Highland PNG populations also have more mtDNA variability and more mtDNA types represented per founding lineage than coastal PNG populations. All of these observations are consistent with a more ancient, restricted origin of highland PNG populations, internal isolation of highland PNG populations from one another and from coastal populations, and more recent and extensive population movements through coastal PNG. An apparent linguistic effect on PNG mtDNA variation disappeared when geography was taken into account. The high resolution technique for examining mtDNA variation, coupled with extensive geographic sampling within a single defined area, leads to an enhanced understanding of the influence of geography on mtDNA variation in human populations.