Principal component analyses of Y-chromosome and mtDNA haplogroup frequencies. The PCA analyses were carried out on haplogroups listed in Additional files 3 and 4. Haplogroups with frequencies lower than 5% in all the populations were not considered. On the whole, 28% of the total variance is represented for the Y-chromosome (16% by the first PC and 12% by the second PC) and 39% for the mtDNA (20% by the first PC and 19% by the second PC). Populations included are: IRM, Marsh Arabs; IRQ, Iraqi; Alb, Albania; Alg-A, Algeria-Arabs; Alg-B, Algeria-Berbers; Aze, Azerbaijan; Ben, Benin; Bos, Bosnia; Bul, Bulgaria; Cau, Caucasus; Crt, Crete; Cro, Croatia; Cze, Czech Republic; Dru, Druze; Egy, Egypt; Egy-A, Egypt-Arabs; S-Egy, South Egypt; N-Egy, North Egypt; Eth-A, Ethiopia-Amhara; Eto-O, Ethiopia-Oromo; Geo, Georgia; Gre, Greece; Hun, Hungary; Ind, India; Ind-AA, India-Austro-Asiatics; Ind-D, India-Dravidians; Ind-IN, India-Indo-Europeans; Ind-TB, India-Tibeto-Burmans; N-Eur, North Europe (Austria, Germany, Ireland, North Italy, Poland, Scotland); N-Irn, North Iran; S-Irn, South Iran; IRN, Iran; NeI, North East Italy; C-Ita, Central Italy; S-Ita, South Italy; Sar, Sardinia; Jor, Jordan; Kur, Kurds; Leb-C, Lebanon-Christians; Leb-D, Lebanon-Druze; Leb-M, Lebanon-Muslims; Mar, Morocco; Ber, Morocco-Berbers; Oma, Oman; Pak, Pakistan; Pak-D, Pakistan-Dravidians; Pak-B, Pakistan-Burushaski; Pak-IE, Pakistan-Indo-Europeans; Pal, Palestinian; Pol, Poland; Qat, Qatar; Rwa-H, Rwanda-Hutu; Rwa-T, Rwanda-Tutsi; Sau, Saudi Arabia; Slv, Slovenia; Som, Somalia; Spa, Spain; Sud-A, Sudan-Arabs; Sud-N, Sudan-Niloti; Taj, Tajikistan; Tun, Tunisia; Tur, Turkey; Tuk, Turkmenistan; Ukr, Ukraine; Uae, United Arab Emirates; Yem, Yemen (Details in Additional files 3 and 4).