Inferring the Genetic Ancestry of Ubykh People from North Caucasus

Abstract

Ubykh people inhabited the area of what now is Greater Sochi, one time being neighbors of the Abkhaz and Adyghe. In 1864, after the Caucasian War, a small group of Ubykh survivors migrated to Turkey. The Ubykh language is a branch of the Northwest Caucasian (Abkhazo-Adyghe) languages, which is either placed in the Abkhaz or Adyghe subgroup or distinguished in a separate subgroup, according to various classifications. All this makes Ubykhs an important but genetically unexplored part of the gene pool of the Caucasus population. We collected an exclusive sample (N = 36) of Ubykh individuals, mainly from their diaspora in Turkey. Application of a high resolution panel of Y-chromosome markers (59 SNP and 17 STR) revealed the major West Caucasus haplogroup G2 (75% of the Ubykh population) and pan-Eurasian haplogroup R1a (19%). Within the G2 haplogroup, we identified 14 branches and genotyped 14 branch-defining markers. The frequencies of the same 14 markers in 19 other populations of the Caucasus were included for comparison. Both the genetic distances and the gene geographical map of the most frequent subhaplogroup (defined by the YY1215 marker at the GRCh37 position 8903699, comprising 50% of the Ubykh sample) revealed similarity of the Ubykh and Adyghe populations. Other Abkhaz-Adyghe-speaking populations appear to be at a greater genetic distance from the Ubykhs, similar to the distance to the Turkic-speaking groups of the North Caucasus. The Ossetian gene pool has little in common with Ubykhs, thus contradicting the hypothesis of the Alanian substrate in Ubykhs. Other populations of the Caucasus and Transcaucasia (of Nakh-Daghestanian and Kartvelian linguistic groups) do not show apparent genetic similarities to Ubykhs.