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mtDNA Haplogroup I
Haplogroup I is a predominately Eurasian lineage.
Origin
Haplogroup I is a descendant (subclade) of haplogroup N1e'I (Behar 2012b) and sibling of haplogroup N1e (Behar 2012b). It is believed to have arisen somewhere in Eurasia between 17,263 and 24,451 years before present (Behar 2012b). It has been suggested that its origin may be in northern Iran or in Europe towards the Carpathian Mountain region where its highest frequency is found (Terreros 2011).
Some argue that it may have been one of the first haplogroups to move into Europe.The distribution of haplogroup I also differs between the northern (9.7%) and southern (1.7%) regions of Iran. This incongruence is significant at a 0.05 (Po0.03) but not following the application of the Bonferroni adjustment (Supplementary Table 3). It is noteworthy that, with the exception of its northern neighbor Azerbaijan, IN is the only population in which haplogroup I exhibits polymorphic levels. Also, a contour plot based on the regional phylogeographic distribution of the I haplogroup exhibits frequency clines consistent with an Iranian cradle (panel I in Figure 3a). Moreover, when compared with other populations in the region, those from the Levant (Iraq, Syria and Palestine) and the Arabian Peninsula (Oman and UAE) exhibit significantly lower proportions of I individuals (1–2%; Supplementary Table 3). It should be noted that this haplogroup has been detected in European groups (Krk, a tiny island off the coast of Croatia (11.3%),78 and Lemko, an isolate from the Carpathian Highlands (11.3%)79) at comparable frequencies to those observed in the North Iranian population. However, the higher frequencies of the haplogroup within Europe are found in geographical isolates and are likely the result of founder effects and/or drift.79 In addition, several studies 5,34,36,80 report the Middle East as the origin of this haplogroup, but for unknown reasons, the prevalence of this lineage in the region has been lost. Thus, it is plausible that the high levels of haplogroup I present in IN may be the result of a localized enrichment through the action of genetic drift or may signal geographical proximity to the location of origin.
Terreros 2011
Distribution
Haplogroup I is found at very low frequencies (generally < 3%) throughout Europe, West Asia and South Asia (Fernandes 2012). This spread is thought to be the product of multiple migration waves from the Arabian Gulf region, Anatolia, and southeast Europe (Fernandes 2012).
Finally, ∼30 ka ago, N1e split from haplogroup I. The three N1e sequences in the tree are located in the Arabian Peninsula and Russia. Haplogroup I, which is by far the most frequent clade within N1, dates to ∼25 ka ago and is overall most frequent in Europe (Figure 2A), but the facts that it has a frequency peak in the Gulf region and that its highest diversity values are in the Gulf, Anatolia, and southeast Europe suggest that its origin is most likely in the Near East and/or Arabia (Figures S4A and S5A). A subhaplogroup of I5a shows a recent tight founder effect ∼2 ka ago on Soqotra, an island that is found in the Gulf of Aden and which was settled during the Holocene.27 I4 and I2′I3, dating to 10–15 ka ago, are both predominantly European. In the HVS-I founder analysis, haplogroup I indicates a primarily Late Glacial expansion, but the I1a subclade peaks in the Neolithic period at ∼6 ka ago under both founder analysis criteria. This pattern is confirmed by the complete sequence tree and again indicates expansion from a probable Near Eastern source dating to ∼5 ka ago.
Fernandes 2012
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Originally Posted by Jonik
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