title: Genetic diversity estimates point to immediate efforts for conserving the endangered Tibetan sheep of India.
abstract: Tibetan is a valuable Himalayan sheep breed classified as endangered. Knowledge of the level and distribution of genetic diversity in Tibetan sheep is important for designing conservation strategies for their sustainable survival and to preserve their evolutionary potential. Thus, for the first time, genetic variability in the Tibetan population was accessed with twenty five inter-simple sequence repeat markers. All the microsatellites were polymorphic and a total of 148 alleles were detected across these loci. The observed number of alleles across all the loci was more than the effective number of alleles and ranged from 3 (BM6506) to 11 (BM6526) with 5.920 ± 0.387 mean number of alleles per locus. The average observed heterozygosity was less than the expected heterozygosity. The observed and expected heterozygosity values ranged from 0.150 (BM1314) to 0.9 (OarCP20) with an overall mean of 0.473 ± 0.044 and from 0.329 (BM8125) to 0.885 (BM6526) with an overall mean 0.672 ± 0.030, respectively. The lower heterozygosity pointed towards diminished genetic diversity in the population. Thirteen microsatellite loci exhibited significant (P < 0.05) departures from the Hardy-Weinberg proportions in the population. The estimate of heterozygote deficiency varied from - 0.443 (OarCP20) to 0.668 (OarFCB128) with a mean positive value of 0.302 ± 0.057. A normal 'L' shaped distribution of mode-shift test and non-significant heterozygote excess on the basis of different models suggested absence of recent bottleneck in the existing Tibetan population. In view of the declining population of Tibetan sheep (less than 250) in the breeding tract, need of the hour is immediate scientific management of the population so as to increase the population hand in hand with retaining the founder alleles to the maximum possible extent.
authors.affiliation: National Bureau of Animal Genetic Resources, Karnal 132 001, India.
authors.forename: Rekha
authors.initials: R
authors.lastname: Sharma
authors.affiliation: ICAR Research Complex for NEH Region, Sikkim Centre, Gangtok 737102, India.
authors.forename: Brijesh
authors.initials: B
authors.lastname: Kumar
authors.affiliation: National Bureau of Animal Genetic Resources, Karnal 132 001, India.
authors.forename: Reena
authors.initials: R
authors.lastname: Arora
authors.affiliation: National Bureau of Animal Genetic Resources, Karnal 132 001, India.
authors.forename: Sonika
authors.initials: S
authors.lastname: Ahlawat
authors.affiliation: National Bureau of Animal Genetic Resources, Karnal 132 001, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Mishra
authors.affiliation: National Bureau of Animal Genetic Resources, Karnal 132 001, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Tantia
keywords: Bottleneck; Genetic diversity; Heterozygote deficiency; Microsatellite markers; Tibetan sheep