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Similar to heritability its type and estimation of it
heritability its type and estimation of it
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- 2. Submitted bySubmitted by YAMGARSAMBHAJI VISHNU.YAMGAR SAMBHAJI VISHNU. Ph.D –I YEARPh.D –I YEAR •PRESENTATION ON Submitted toSubmitted to Dr. N.S. Kute.Dr. N.S. Kute. Seminar InchargeSeminar Incharge Department of Agricultural BotanyDepartment of Agricultural Botany (Genetics and Plant breeding).(Genetics and Plant breeding). MAHATMA PHULE KRUSHI VIDYAPEETH, RAHURI.MAHATMA PHULE KRUSHI VIDYAPEETH, RAHURI. HERITABILITY AND GENETIC ADVANCE •2
- 3. • HeritabilityHeritability •IntroductionIntroduction • • conclusionconclusion • Estimationof heritabilityEstimation of heritability •Types of Heritability.Types of Heritability. •Broad sence HeritabilityBroad sence Heritability •Narrow sence heritability.Narrow sence heritability. .. •3
- 4. . Heritabilityis the proportion of the total phenotypic variation controlled by genetic rather than environmental factors.
- 5. or It is goodindex of transmission of character from parent to their Offspring (Falconer,1960). Heritability H = VG / VP X 100 VP= VG+ VE Where The total phenotypic variance may be decomposed: VP = total phenotypic variance VG = total genetic variance VE = environmental variance
- 6. Broad senseheritability: (Lush,1940) It is the ratio of genotypic variance (VG) to the total phenotypic variance (VP) h2 (bs) = VG / VP X 100 VP= VG+ VE The total phenotypic variance may be decomposed: VP = total phenotypic variance VG = total genetic variance VE = environmental variance
- 7. Heritability valuesare characterized as fallow. Low- less than 30% Moderate: 30-60% High- More than 60% (Johnson et al. 1955). Useful in selection of elite types from homozygous population. Can be estimated from both parental and segregating material. Estimated from total genetic variance
- 8. Narrow senseheritability: It is the ratio of additive genetic variance (VA) to the total phenotypic variance (VP) (Smith, 1952). h2 (ns) = VA/ VP x 100 . The total genetic variance (VG) may be decomposed: VA = additive genetic variance VD = dominance genetic variance VI = epistatic (interactive) genetic variance Summary: Vp= VA+ VD+ VI+ VE+ VGE
- 9. The magnitudeof narrow sense heritability is always less than or equal to broad since heritability. Useful in selection of elite types from segregating material. Narrow sense heritability is classified as follow. Low-5 to 10 % Medium-10-30% High- more than 30% Robinson et.al(1966)
- 10. Broad sense heritability- Itrequire estimation of genetic variance in a population . It is estimated as two way 1) Simple trials-h2 (bs) = VG / VP X 100 VP= VG+ VE The total phenotypic variance may be decomposed: VP = total phenotypic variance VG = total genetic variance VE = environmental variance 2) From Generation mean analysis- ( VF2 - VF1) / VF2 X 100 Where VF2, VF1 are variance of F1 and F2 respectively
- 11. For the estimationof narrow sense heritability require estimation of additive genetic variance 1)Diallel Analysis h2 (ns) = (1/2 D + ½ H1- ½ H2 – ½ F) X 100 (1/2 D + ½ H1- ¼ H2 – ½ F+ E) 2) Generation mean analysis. Heritability= ½ D / VF2 X 100 Warner (1952)…. Heritability = D/ (D+H+E) X 100 Mather (1949)…
- 12. Broad sense heritabilityNarrow sense heritability Estimated from total genetic variance. Can be estimated from both parental and segregating material. More useful in animal breeding. Useful in selection of elite types from homozygous population. Estimated from additive genetic variance. Requires crossing in a definite fashion. Useful in both plant and animal breeding. Useful in selection of elite types from segregating material.
- 13. Genetics population Sample size- random Sampling. Method of computation- Variance component method , Parent offspring regression.
- 14. Because itallows us to predict a trait’s response to selection R = h2 S R = response to selection h2 = heritability S = selection differential
- 15. It isuseful in predicting the effectiveness of selection. It is also helpful for deciding breeding methods to be followed, for effective selection. It gives an idea about the response of various characters to selection pressure. It is useful in predicting the performance under different degree of intensity of selection. It helps for construction of selection index. Estimates of heritability serve as a useful guide to the breeder, to appreciate the proportion of variation, which is due to genotypic or additive effects.
- 16. The Limitations ofHeritability • Heritability does not indicate the degree to which a characteristic is genetically determined. • Pure breed no polydactilly rabbits: still polydactilly can happen • An individual does not have heritability. • Narrow-sense heritability of 0.6 in population does not indicate that an individual’s characteristic is 60% additive • There is no universal heritability for a characteristic. • Two populations will have different heritability due to environment • Even when heritability is high, environmental factors may influence a characteristic. • Human height • Heritability indicates nothing about the nature of population differences in a characteristic.
- 17. If broadscenes heritability is high character is least influenced by Env. Selection is not desirable. If broad sense heritability is low character highly influenced by Env.Due to masking effect of genes. If narrow heritability is high character is governed by additive fixable genes.(selection method) If narrow heritability is low character is governed by non-additive ,non-fixable genes. (Heterosis breeding Useful)
- 18. Improvement inthe mean genotypic value of selected plants over the parental population is known as genetic advance. Gs = (K) (σp) (H) Where, Gs: Genetic advance under selection K : Selection differential σp : Phenotypic standard deviation of base population H : heritability
- 19. Genetic variability: Greaterthe variability, higher will be the genetic advance and vice versa. Heritability: genetic advance is generally high with the character having high heritability and vice versa. Selection intensity: It is the proportion of plants selected from population. The high selection intensity generally gives better results than the low selection intensity.
- 20. Estimates of GAare based on empirical results and free from genetic improvement under selection for polygenic traits. GA can be estimated both from parental as well as segregating population. Estimates of GA helps in understanding the types of gene action involved into the expression of various polygenic characters. High values of GA are indicative of additive gene action. It also helps in deciding a breeding procedure for the genetic improvement of various polygenic traits by determining the gene actions.
- 21. Disadvantages ofgenetic advance: Estimates of GA are based on variance and therefore, not statistically very robust. Estimates of GA are specific to the breeding material and hence it varies according to the breeding material.
- 22. If value ofgenetic value is high show character is governed by additive gene (Selection method rewarding) If value of genetic value is low show character is governed by non-additive genes(Heterosis breeding rewarding)
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- 24. High heritabilitywith high genetic advance character is governed by additive genes fixable gene, Selection desirable. If heritability is high and low genetic advance character is governed by non-additive ,fixable genes.(selection not rewarding) If heritability is low with high genetic advance character is governed by additive gene effects If heritability is low with low genetic advance character is highly influenced by Env.