Carriers of mitochondrial DNA macrohaplogroup R colonized Eurasia and Australasia from a southeast Asia core area

Abstract

BackgroundThe colonization of Eurasia and Australasia by African modern humans has been explained, nearly unanimously, as the result of a quick southern coastal dispersal route through the Arabian Peninsula, the Indian subcontinent, and the Indochinese Peninsula, to reach Australia around 50 kya. The phylogeny and phylogeography of the major mitochondrial DNA Eurasian haplogroups M and N have played the main role in giving molecular genetics support to that scenario. However, using the same molecular tools, a northern route across central Asia has been invoked as an alternative that is more conciliatory with the fossil record of East Asia. Here, we assess as the Eurasian macrohaplogroup R fits in the northern path.ResultsHaplogroup U, with a founder age around 50 kya, is one of the oldest clades of macrohaplogroup R in western Asia. The main branches of U expanded in successive waves across West, Central and South Asia before the Last Glacial Maximum. All these dispersions had rather overlapping ranges. Some of them, as those of U6 and U3, reached North Africa. At the other end of Asia, in Wallacea, another branch of macrohaplogroup R, haplogroup P, also independently expanded in the area around 52 kya, in this case as isolated bursts geographically well structured, with autochthonous branches in Australia, New Guinea, and the Philippines.ConclusionsCoeval independently dispersals around 50 kya of the West Asia haplogroup U and the Wallacea haplogroup P, points to a halfway core area in southeast Asia as the most probable centre of expansion of macrohaplogroup R, what fits in the phylogeographic pattern of its ancestor, macrohaplogroup N, for which a northern route and a southeast Asian origin has been already proposed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0964-5) contains supplementary material, which is available to authorized users.

Carriers of mitochondrial DNA macrohaplogroup L3 basic lineages migrated back to Africa from Asia around 70,000 years ago

“…However, we realized that what actually macrohaplogroup N points to is a human movement from southeastern Asia to western Asia [53]. We observed the same sense for macrohaplogroup M. In this case, expanding westwards to India [54], and a similar trend follows macrohaplogroup R, the main sister branch of N [55]. Thus, we confirmed that macrohaplogroup M and N indicated, respectively, major southern and northern expansions of modern humans but, ironically, in the opposite sense we predicted long ago [4].…”

“…Under this assumption, it is expected that, in general, coalescence ages of haplogroups should decrease from Africa to Australia. However, we have demonstrated that this is not the case [53–55]. Just on the contrary, The oldest M and N haplogroups are detected in southern China and Australasia instead of India, and associations between longitudinal geographic distances and relative ages of M and N haplogroups run, against to expectation, westwards with younger haplogroup ages going to Africa [53, 54].…”

“…Confronted with the northern foothills of the Himalayas, humans moved in two directions, westwards to return to Africa, and eastwards to reach southeastern Asia across China (Figure 1b). The second part of this model has been already outlined in precedent articles [53–55].…”

A different paradigm for the initial colonisation of Sahul

“…Larruga et al . ) to indicate an offshore origin for earliest Sahul representatives of this haplogroup. Others prefer an intra‐Sahul emergence based on similar estimated time depths for P9‐10 versus Australian P subtypes (Nagle et al .…”

Counterbalancing the time-dependence effect on the human mitochondrial DNA molecular clock

“…In this paper, when distributing mutations of lineages with significant rate differences within coalescent periods, we have used a simple proportionality criterion. We allowed a window from 0 to 5 mutations between sequences as it has been demonstrated that, under a Poisson distribution, even in an extended period of 10,000 years, there could be lineages still carrying the same mutations that their common ancestor, and lineages that have accumulated five new mutations with probabilities higher than 0.05 percent 35 .…”