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ارزیابی ژنگانی اندازة مؤثر جمعیت برخی از نژادهای گوسفند ایرانی با استفاده از اطلاعات عدم تعادل پیوستگی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 استادیار گروه علوم دامی، دانشکدة کشاورزی و منابع طبیعی، دانشگاه اراک، اراک، ایران

2 دانشیار گروه علوم دامی، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران، کرج، ایران

چکیده

هدف از این تحقیق برآورد اندازة مؤثر (Ne) برخی از نژادهای گوسفند ایرانی با استفاده از اطلاعات نشانگرهای SNP در سطح ژنگان (ژنوم) بود. به این منظور از اطلاعات ژنگانی مجموع 217 نمونه حیوان شامل 45، 37، 34، 35، 45 و 11 نمونه به‌ترتیب از نژادهای زل، افشاری، مغانی، قزل، لری­بختیاری و یک نژاد گوسفند وحشی ایرانی که با استفاده از آرایه­های Illumina OvineSNP50K Beadchip تعیین ژنوتیپ شده­اند، استفاده شد. این تحقیق با همکاری پروژة Sheep HapMap انجام شد. اندازة مؤثر با استفاده از اطلاعات نداشتن تعادل پیوستگی (لینکاژی) در طی 4 تا 3500 نسل پیش محاسبه شد. نتایج تجزیة مؤلفه­های واریانس (PCA) نشان داد که همة نژادها با استفاده از دو مؤلفة اول از همدیگر مجزا می­شوند. میانگین ناخالصی (هتروزیگوسیته) مورد انتظار و مشاهده‌شده در نژادهای مختلف به‌ترتیب در دامنة 37/0-36/0 و 43/0-37/0 به­دست آمد. نتایج به‌دست‌آمده از محاسبة اندازة مؤثر در نژادهای مختلف، نشان­دهندة روند کاهش تدریجی Ne در طی 3500 سال گذشته تاکنون با یک شیب کاهشی زیاد در حدود 550 نسل پیش برای همة نژادها بود. اندازه Ne در نسل­های حاضر (4 نسل قبل) در نژادهای گوسفند ایرانی در دامنه 89-9 رأس بود. بیشترین Ne در نژاد زل (89 رأس) و کمترین در نژادهای افشاری (44 رأس) و نژاد وحشی گوسفند (9 رأس) مشاهده شد. درمجموع، نتایج این تحقیق نشان داد که باوجود تنوع ژنتیکی مناسب در این جمعیت­ها، اندازة مؤثر آن‌ها به‌ویژه در نژاد گوسفند افشاری و نژاد وحشی در طی نسل­های اخیر به‌شدت کاهش یافته است و طراحی برنامه­های مناسب برای حفاظت از حیوانات خالص باقی‌ماندة این نژادهای بومی ضروری است.

کلیدواژه‌ها


عنوان مقاله [English]

Genome-wide evaluation of effective population size in some Iranian sheep breeds using linkage disequilibrium information

نویسندگان [English]

  • Mohammad Hossein Moradi 1
  • Amir Hossein Farahani 1
  • Ardeshir Nejati-Javaremi 2
1 Assistant Professor, Department of Animal Science, Faculty of Agriculture and Natural Resources, Arak University, Arak 38156-8-8349, Iran
2 Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Iran
چکیده [English]

The aim of the present study was to estimate the effective population size (Ne) in some Iranian sheep breeds using genome wide SNP data. A total of 217 animal samples consisting of 45, 37, 34, 35, 45 and 11 samples from Zel, Afshari, Moghani, Qezel, Lori-Bakhtiari and a wild-type of Iranian sheep breeds, genotyped by Illumina OvineSNP50K Beadchip assay were used in this study respectively. This study has been performed in collaboration with the Ovine HapMap project. The Ne was estimated using linkage disequilibrium across 4 up to 3500 generations ago. The result of principal component analysis (PCA) indicated that all breeds will be separated from each other in the first two principal components. Average expected and observed heterozygosity for different breeds ranged 0.36-0.37 and 0.37-0.43 respectively. The Ne results showed a decreasing trend over the last 3500 generations for all breeds, with an increasingly slope since about last 550 generations. The Ne in Iranian sheep breeds for 4 generations ago were ranged from 9 up to 89. The highest historically effective population size was found for Zel breed (89 heads) and the lowest for Afshari (44 heads) and wild_type (9 heads) sheep breeds. Generally, the results indicated that although a considerable genetic variation exists in these populations, however Ne has been decreased strongly in Iranian sheep breeds especially in Afshari and wild-type sheep breeds during recent years and designing of appropriate programs is necessary to conserve remaining purebred animals of these indigenous sheep breeds. 

کلیدواژه‌ها [English]

  • effective population size
  • genetic conservation
  • genome wide evaluation
  • Iranian sheep breeds
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