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volume 47 issue 1 (february 2013) : 35-39

ASSESSING GENETIC VARIABILITY IN A FLOCK OF AFSHARI SHEEP BY GENEALOGICAL DATA

M
Moradpasha Eskandarinasab1
F
Farhad Ghafouri-Kesbi*
1*Islamic Azad University, Karaj Branch, Karaj, Iran.

  • Submitted|

  • First Online |

  • doi

Cite article:- Eskandarinasab1 Moradpasha, Ghafouri-Kesbi* Farhad (2025). ASSESSING GENETIC VARIABILITY IN A FLOCK OF AFSHARI SHEEP BY GENEALOGICAL DATA. Indian Journal of Animal Research. 47(1): 35-39. doi: .

ABSTRACT

The aim of this study was to investigate genetic diversity in a nucleus flock of Afshari sheep using measures based on the probability of identity-by-descend of genes (coancestry, ƒ, inbreeding, F, average relatedness, AR, and effective population size, Ne), as well as measures based on probabilities of gene origin (effective number of founders, ƒe, effective number of ancestors, ƒa, effective number of founder genomes, ƒg, and effective number of non-founder genomes, ƒne). The average coancestry (f), inbreeding (F), and relatedness (AR) in the whole population were 1%, 0.5%, and 2%, respectively. The estimated value of the effective population size () was 58. Effective number of founders was estimated to be 62 which was one fourth of the total number of founders, indicating the loss of diversity due to the unequal contribution of founders in such a way that only 62 founders covered 75% of the total genetic diversity. The effective number of ancestors (fa) was 49. Only 18 ancestors were needed to explain 50% of the genetic diversity in the population. The marginal contribution of the most influential ancestor was 6.5%. This was 5.8% and 4.8% for the 2nd and 3rd most influential ancestors. Effective number of founder genomes which covered all of the losses in genetic diversity during segregation was computed to be 41 and the effective number of non-founder genomes was 125. While the level of inbreeding was low, it was concluded that the rate of inbreeding needs to be controlled in the future to avoid further decline in genetic diversity.

REFERENCES

  1. Boichard, D., Maignel, L., and Verrier, E. (1997). The value of using probabilities of gene origin to measure genetic variability in a population. Genet. Sel. Evol., 29: 5–23.
  2. Bijma, P. (2000). Long-term genetic contributions. Prediction of rates of inbreeding and genetic gain in selected populations. Ph.D. dissertation, Wageningen University, Netherlands.
  3. Brah, G.S., Chaudhary., M.L., Saini, S., and Bajwa, I.S. (2012). Phenotypic and genetic evaluation of a randombred control population of White Leghorn over 20 generations. Indian. J. Anim. Sci., 82: 74–80.
  4. Caballero, A., and Toro, M.A. (2000). Interrelations between effective population size and other pedigree tools for the management of conserved populations. Genetic Res., 75: 331–343.
  5. Eskandarinasab, M.P., Ghafouri-Kesbi, F., and Abbasi, M.A. (2010). Different models for evaluation of growth traits and Kleiber ratio in an experimental flock of Iranian fat-tailed Afshari sheep. J. Anim. Breed. Genet., 127:26–33.
  6. Falconer, D.S., and MacKay, T.F.C. (1996). Introduction to Quantitative Genetics. 4th edition. Longman Group Press, 438 pp. Harlow, Essex, UK/New York.
  7. Ghafouri-Kesbi, F. (2010). Analysis of genetic diversity in a close population of Zandi sheep using genealogical information. J. Genet., 89: 479–483.
  8. Goyache, F., Gutiérrez, J.P., Fernández, I., Gómez, E., Álvarez, I., Díez, J., and Royo, L.J. (2003). Using pedigree information to monitor genetic variability of endangered populations: the Xalda sheep breed of Asturias as an example. J. Anim. Breed. Genet., 120: 95–103.
  9. Gutiérrez, J.P., and Goyache, F. (2005). A note on ENDOG: a computer program for analysing pedigree information. J. Anim. Breed. Genet., 122: 357–360.
  10. Gutiérrez, J.P., Cervantes, I., and Goyache, F. (2009). Improving the estimation of realized effective population sizes in farm animals. J. Anim. Breed. Genet., 126: 327–332.
  11. Lacy, R.C. (1989). Analysis of founder representation in pedigrees: founder equivalents and founder genome equivalents. Zoo Biology., 8: 111–123.
  12. Lacy, R.C. (1995). Clarification of genetic terms and their use in the management of captive populations. Zoo Biology., 14: 565–578.
  13. Malécot, G. (1948). Les Mathématiques de l´Hérédité. Masson et Cie Press. Paris.
  14. Mandal, A., Pant, K.P., Rout, P.K., Singh, S.A., and Roy, R. (2002). Influence of inbreeding on growth traits of Muzaffarnagari sheep. Indian. J. Anim. Sci., 72: 988-990.
  15. Meuwissen, T.H.E. and Luo, Z. (1992). Computing inbreeding coefficients in large populations. Genet. Sel. Evol., 24: 305–313.
  16. NRC, National Research Council. (1985). Nutrient Requirements of Sheep, sixth rev. ed. National Academy Press, Washington, DC, USA.
  17. Oravcova, M., and Krupa, E. (2011). Pedigree analysis of the Former valachian sheep. Slovak. J. Anim. Sci., 44: 6–12.
  18. Pirchner, F. (1983). Population Genetics in Animal Breeding. 2nd ed,. Plenum Press, New York 250 pp.
  19. Sørensen, A.C., Sørensen, M.K., and Berg, P. (2005). Inbreeding in Danish dairy cattle breeds. J. Dairy. Sci., 88:1865–1872.
  20. Wright, S. (1931) Evolution in Mendelian populations. Genetics., 16: 97–159.
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    volume 47 issue 1 (february 2013) : 35-39

    ASSESSING GENETIC VARIABILITY IN A FLOCK OF AFSHARI SHEEP BY GENEALOGICAL DATA

    M
    Moradpasha Eskandarinasab1
    F
    Farhad Ghafouri-Kesbi*
    1*Islamic Azad University, Karaj Branch, Karaj, Iran.

    • Submitted|

    • First Online |

    • doi

    Cite article:- Eskandarinasab1 Moradpasha, Ghafouri-Kesbi* Farhad (2025). ASSESSING GENETIC VARIABILITY IN A FLOCK OF AFSHARI SHEEP BY GENEALOGICAL DATA. Indian Journal of Animal Research. 47(1): 35-39. doi: .

    ABSTRACT

    The aim of this study was to investigate genetic diversity in a nucleus flock of Afshari sheep using measures based on the probability of identity-by-descend of genes (coancestry, ƒ, inbreeding, F, average relatedness, AR, and effective population size, Ne), as well as measures based on probabilities of gene origin (effective number of founders, ƒe, effective number of ancestors, ƒa, effective number of founder genomes, ƒg, and effective number of non-founder genomes, ƒne). The average coancestry (f), inbreeding (F), and relatedness (AR) in the whole population were 1%, 0.5%, and 2%, respectively. The estimated value of the effective population size () was 58. Effective number of founders was estimated to be 62 which was one fourth of the total number of founders, indicating the loss of diversity due to the unequal contribution of founders in such a way that only 62 founders covered 75% of the total genetic diversity. The effective number of ancestors (fa) was 49. Only 18 ancestors were needed to explain 50% of the genetic diversity in the population. The marginal contribution of the most influential ancestor was 6.5%. This was 5.8% and 4.8% for the 2nd and 3rd most influential ancestors. Effective number of founder genomes which covered all of the losses in genetic diversity during segregation was computed to be 41 and the effective number of non-founder genomes was 125. While the level of inbreeding was low, it was concluded that the rate of inbreeding needs to be controlled in the future to avoid further decline in genetic diversity.

    REFERENCES

    1. Boichard, D., Maignel, L., and Verrier, E. (1997). The value of using probabilities of gene origin to measure genetic variability in a population. Genet. Sel. Evol., 29: 5–23.
    2. Bijma, P. (2000). Long-term genetic contributions. Prediction of rates of inbreeding and genetic gain in selected populations. Ph.D. dissertation, Wageningen University, Netherlands.
    3. Brah, G.S., Chaudhary., M.L., Saini, S., and Bajwa, I.S. (2012). Phenotypic and genetic evaluation of a randombred control population of White Leghorn over 20 generations. Indian. J. Anim. Sci., 82: 74–80.
    4. Caballero, A., and Toro, M.A. (2000). Interrelations between effective population size and other pedigree tools for the management of conserved populations. Genetic Res., 75: 331–343.
    5. Eskandarinasab, M.P., Ghafouri-Kesbi, F., and Abbasi, M.A. (2010). Different models for evaluation of growth traits and Kleiber ratio in an experimental flock of Iranian fat-tailed Afshari sheep. J. Anim. Breed. Genet., 127:26–33.
    6. Falconer, D.S., and MacKay, T.F.C. (1996). Introduction to Quantitative Genetics. 4th edition. Longman Group Press, 438 pp. Harlow, Essex, UK/New York.
    7. Ghafouri-Kesbi, F. (2010). Analysis of genetic diversity in a close population of Zandi sheep using genealogical information. J. Genet., 89: 479–483.
    8. Goyache, F., Gutiérrez, J.P., Fernández, I., Gómez, E., Álvarez, I., Díez, J., and Royo, L.J. (2003). Using pedigree information to monitor genetic variability of endangered populations: the Xalda sheep breed of Asturias as an example. J. Anim. Breed. Genet., 120: 95–103.
    9. Gutiérrez, J.P., and Goyache, F. (2005). A note on ENDOG: a computer program for analysing pedigree information. J. Anim. Breed. Genet., 122: 357–360.
    10. Gutiérrez, J.P., Cervantes, I., and Goyache, F. (2009). Improving the estimation of realized effective population sizes in farm animals. J. Anim. Breed. Genet., 126: 327–332.
    11. Lacy, R.C. (1989). Analysis of founder representation in pedigrees: founder equivalents and founder genome equivalents. Zoo Biology., 8: 111–123.
    12. Lacy, R.C. (1995). Clarification of genetic terms and their use in the management of captive populations. Zoo Biology., 14: 565–578.
    13. Malécot, G. (1948). Les Mathématiques de l´Hérédité. Masson et Cie Press. Paris.
    14. Mandal, A., Pant, K.P., Rout, P.K., Singh, S.A., and Roy, R. (2002). Influence of inbreeding on growth traits of Muzaffarnagari sheep. Indian. J. Anim. Sci., 72: 988-990.
    15. Meuwissen, T.H.E. and Luo, Z. (1992). Computing inbreeding coefficients in large populations. Genet. Sel. Evol., 24: 305–313.
    16. NRC, National Research Council. (1985). Nutrient Requirements of Sheep, sixth rev. ed. National Academy Press, Washington, DC, USA.
    17. Oravcova, M., and Krupa, E. (2011). Pedigree analysis of the Former valachian sheep. Slovak. J. Anim. Sci., 44: 6–12.
    18. Pirchner, F. (1983). Population Genetics in Animal Breeding. 2nd ed,. Plenum Press, New York 250 pp.
    19. Sørensen, A.C., Sørensen, M.K., and Berg, P. (2005). Inbreeding in Danish dairy cattle breeds. J. Dairy. Sci., 88:1865–1872.
    20. Wright, S. (1931) Evolution in Mendelian populations. Genetics., 16: 97–159.
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