Haplogroup D-M55


Haplogroup D-M55 also known as Haplogroup D1a2a is a Y-chromosome haplogroup. It is one of two branches of Haplogroup D1a. The other is D1a1, which is found with high frequency in Tibetans and other Tibeto-Burmese populations and geographical close groups. D is also distributed with low to medium frequency in Central Asia, East Asia, and Mainland Southeast Asia.
Haplogroup D-M55 is found in about 33% of present-day Japanese males. It has been found in fourteen of a sample of sixteen or 87.5% of a sample of Ainu males in one study published in 2004 and in three of a sample of four or 75% of a sample of Ainu males in another study published in 2005 in which some individuals from the 2004 study may have been retested. It is currently the most common Y-DNA haplogroup in Japan if O1-F265 and O2-M122 are considered as separate haplogroups.
In 2017, it was confirmed that the Japanese branch of haplogroup D-M55 is distinct and isolated from other branches of haplogroup D since about 50,000 years ago. The split in D1a may have occurred near the Tibetan Plateau.

History

Among the subgroups of Haplogroup D, the ancestor of D-M55 went eastward to reach the Japanese archipelago. According to Michael F. Hammer of the University of Arizona, haplogroup D originated near the Tibetan Plateau and migrated into Japan where it eventually became D-M55. Mitsuru Sakitani said that Haplogroup D1 came from Tibet to northern Kyushu via the Altai Mountains and the Korean Peninsula more than 50,000 years ago, and Haplogroup D-M55 was born in the Japanese archipelago.
Recent studies suggest that D-M55 became dominant during the late Jōmon period, shortly before the arrival of the Yayoi, suggesting a population boom and bust.

Frequency

The average frequency in Japanese is about 30%. High frequencies are found in various places in Japan, especially in Hokkaidō, eastern Honshū, southern Kyūshū, and Okinawa.

Ancient DNA

A Jōmon period man excavated from Funadomari remains in Rebun Island in Hokkaido belongs to haplogroup D1a2a2a.
The analysis of a Jōmon sample and an ancient sample from the Tibetan Plateau found only partially shared ancestry, suggesting a positive genetic bottleneck regarding the spread of haplogroup D from an ancient population related to the Tibetan Chokhopani sample.

Phylogenetic tree

By ISOGG Tree.