Climate Shaped the Worldwide Distribution of Human Mitochondrial DNA Sequence Variation – Proc. R. Soc. B

Here’s the abstract to a newly published paper, the contents of which are free to access:

There is an ongoing discussion in the literature on whether human mitochondrial DNA (mtDNA) evolves neutrally. There have been previous claims for natural selection on human mtDNA based on an excess of non-synonymous mutations and higher evolutionary persistence of specific mitochondrial mutations in Arctic populations.

However, these findings were not supported by the reanalysis of larger datasets. Using a geographical framework, we perform the first direct test of the relative extent to which climate and past demography have shaped the current spatial distribution of mtDNA sequences worldwide. We show that populations living in colder environments have lower mitochondrial diversity and that the genetic differentiation between pairs of populations correlates with difference in temperature. These associations were unique to mtDNA; we could not find a similar pattern in any other genetic marker.

We were able to identify two correlated non-synonymous point mutations in the ND3 and ATP6 genes characterized by a clear association with temperature, which appear to be plausible targets of natural selection producing the association with climate. The same mutations have been previously shown to be associated with variation in mitochondrial pH and calcium dynamics. Our results indicate that natural selection mediated by climate has contributed to shape the current distribution of mtDNA sequences in humans.

Reference: Climate shaped the worldwide distribution of human mitochondrial DNA sequence variation by François Balloux, Lori-Jayne Lawson Handley, Thibaut Jombart, Hua Liu and Andrea Manica,

Published online before print July 8, 2009, doi: 10.1098/rspb.2009.0752

2 thoughts on “Climate Shaped the Worldwide Distribution of Human Mitochondrial DNA Sequence Variation – Proc. R. Soc. B

  1. I think I have discussed this paper elsewhere (Mathilda’s?) and what really strikes me as unconvincing is fig. 4: Oceanian populations have about the same tropical temperatures but widely diverging rates for the derived alleles, instead Europeans have very divergent temperatures and about the same amount (100%) of derived alleles. Most Europeans are in the same temperature range as most Asians but have much higher rates of derived alleles.

    A good study could have been done maybe using Native Americans, as these have been in the continent for only some 20,000 years now and range between all temperatures. But the few NAs sampled vary wildly, offering only a very very weak confirmation of the hypothesis, with most of them having intermediate, Asian-like, derived alleles, in spite of being sampled mostly in cold and hot latitudes (few in temperate ones).

    Also the “correcting for distance to Africa” sounds like making no sense because Europe and West Asia are just by Africa but were only colonized at a late phase. Instead Australia or China are far away and were colonized early on.

    A risk here is to confuse what is the pattern of human spread, colonizing first Tropical and Subtropical Asia/Australasia, and only later the cold lands of the North with a thermobiological evolutionary pattern.

    Still, they could be onto something but seems like it needs further testing.

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