A short fragment of ancient DNA and its use in determination of sheep mitochondrial dna haplogroups in Southeast Anatolia


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Biyolojik Bilimler Bölümü, Türkiye

Tezin Onay Tarihi: 2013

Öğrenci: NİHAN DİLŞAD DAĞTAŞ

Danışman: İNCİ ZEHRA TOGAN

Özet:

Recent archaeozoological studies indicated that perhaps the oldest (11,000 years before present) and may be the only sheep domestication center was in Southeast Anatolia. In this study, to contribute to the understanding of sheep domestication history, ancient DNA derived from skeletal remains of sheep unearthed from archaeological sites in Turkey mainly from Oylum Höyük in Kilis were examined. 187 ancient metapodia and mandible samples, dating between 1,800-30 BCE were brought from Oylum Höyük to the dedicated aDNA laboratory which was established at the Middle East Technical University in 2012. Similarly, samples already identified as sheep (n=63), dating between 6,700-5,800 BCE from Tepecik-Çiftlik, Niğde were brought to the same aDNA laboratory. Ancient DNA extraction was performed using the samples identified as sheep by the archaeozoologists (n=57 for Oylum Höyük, n=13 for Tepecik-Çiftlik). Then, a 144 bp long mitochondrial DNA fragment which was shown to identify all five of the modern domestic sheep haplogroups A-E, was amplified. Success rates in extractions and amplifications were 65% for Oylum Höyük samples and 92.3% for Tepecik-Çiftlik samples. For 30 out of 37 samples from Oylum Höyük, aDNA amplifications were replicated. Postmortem nucleotide changes (misincorporations) and indels were inferred on the basis of replicated aDNA sequences and reference sequences from modern sheep samples. As the main result, aDNA sequences were used to estimate HPGs of sheep samples. The observed percentage of each haplogroup was: HPG A=50%, HPG B= 35.3%, HPG C=5.9%, HPG D=5.9%, HPG E=2.9% for Oylum Höyük and B= 83%, E= 17% for Tepecik-Çiftlik samples. When HPG distributions were examined comparatively with the accumulated data in the literature, it was observed that HPG B might be the dominating type around the sheep domestication center in the early days of domestication and HPG C frequency increased after the Hellenistic period around Kilis region. The present study being the first study from the sheep domestication center, besides contributing to the understanding of evolutionary history of domestic sheep in South/Southeast Anatolia, also shows that a short mtDNA fragment is useful to determine the HPGs of ancient sheep with respect to the HPGs observed in modern domestic sheep.