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Accueil du site → Doctorat → Inde → 2017 → ASSESSMENT OF GENETIC DIVERSITY IN INDIGENOUS SHEEP BREEDS OF RAJASTHAN USING MOLECULAR MARKERS

Rajasthan University of Veterinary and Animal Sciences, Bikaner (2017)

ASSESSMENT OF GENETIC DIVERSITY IN INDIGENOUS SHEEP BREEDS OF RAJASTHAN USING MOLECULAR MARKERS

KRITIKA GAHLOT

Titre : ASSESSMENT OF GENETIC DIVERSITY IN INDIGENOUS SHEEP BREEDS OF RAJASTHAN USING MOLECULAR MARKERS

Auteur : KRITIKA GAHLOT

Université de soutenance : Rajasthan University of Veterinary and Animal Sciences, Bikaner

Grade : Doctor of Philosophy (Animal Biotechnology) 2017

Résumé
This study illustrates the genetic diversity and relationships within and among four indigenous sheep breeds viz ; Chokla, Nali, Marwari and Magra of the northwestern arid region of Rajasthan. The study was based on the use of eighteen microsatellite markers suggested by FAO (ISAG) for the estimation of genetic diversity in sheep. All the microsatellite markers were polymorphic and a total of 224 alleles, ranging from 8 – 17 (Mean=12.4) were found across 18 microsatellite loci. OarFCB48 was found to be highly polymorphic with a total of 17 alleles and least polymorphic loci were TGLA377 and OarAE129 with 8 alleles observed. The average observed heterozygosity was less than the expected heterozygosity. The observed and expected heterozygosity values ranged from 0.3608 (BM827) to 0.6598 (OarHH35, BM8125) with an overall mean of 0.5464 ± 0.0871 and from 0.7275 (BM757) to 0.9022 (OarJMP29) with an overall mean 0.8530±0.0417, respectively. The overall polymorphic information content (PIC) value in 4 breeds of sheep was also found high (>0.5) and ranged between 0.6799 (BM757) and 0.8634 (OarHH64). The estimate of heterozygote deficiency varied from 0.161 (CSSM31) to 0.520 (TGLA137) with a mean positive value of 0.325±0.024, suggesting a deficit of heterozygotes in all four breeds. The Mode shift analysis revealed a normal “L” shaped curve indicating all sheep breeds are non-bottlenecked. The geneftic differentiation estimate (FST = 9%) suggesting low levels of differentiation between the breeds. Ewens–Watterson Test for Neutrality revealed that 66.6% loci in Chokla, 77.7% in Nali, 66.6% in Marwari and 94.4% in Magra breed were neutral and attributed to the non-random mating among the individuals of the population. The Genetic distance among the breeds revealed a close relationship between the Nali and Marwari (0.504) and maximum distance was found between Marwari and Magra (0.702) sheep. Phylogenetic analysis was based on the UPGMA method further supported close genetic relationship between Nali-Marwari breeds as they clustered in one group, on the other hand Chokla and Magra showed clear distinctness and clustered in another group of sheep breeds.

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Page publiée le 31 janvier 2021