Heritability

heritability

[‚her·əd·ə′bil·əd·ē] (genetics) In a population, the ratio of the total genetic variance to the total phenotypic variance.

Heritability

the degree to which the phenotypic variation of any trait in a population of animals or plants (or group of them) is determined by the genotypic differences among individuals.

The term “heritability” was introduced in 1939 by the American geneticist J. Lush. The total variation in a population is the total result of genotypic variation and the variation caused by environmental factors. Since the degree of variation can be measured by variance (that is, the square of the mean of the square deviation of the variants from the mean of the variational series), the population-genetic parameter h², or the coefficient of heritability, is used to characterize heritability. The formula in the broad sense is:

where σp² is the total phenotypic variance, σg² is the genotypic variance determined by the genotypic differences among individuals, and σE² is the variance caused by fluctuations in the environment. h₁², the coefficient of heritability in the narrow sense, is also distinguished: h₁² = σA²/σp2; in this case account is taken not of the entire genotypic variation but only of one of its components σA², the variance determined by the differences in the additive genes (the effect of these genes on a trait is summed arithmetically). The σA² index is important for selection because selection is achieved mainly through additive genes or polygenes.

The values of h² and h₁² are expressed in fractions of less than 1, less often in percent. The special methods available for determining h² are based chiefly on establishing the phenotypic resemblance among individuals related to different degrees for which correlation, regression, and other factors are used. The coefficient of heritability applies only to populations and not to individuals. The values of h² depend on the nature of the trait studied. For example, the traits associated with reproduction have fairly low h² (for example, h² of fertility in sheep, pigs, and mice is 0.1–0.2), whereas constitutional traits are fairly high h² (h² of head length in cattle is 0.6–0.7, and h² of skin folds in sheep 0.5–0.8).

The differences between h² of economically useful traits in specific herds of breeding animals and plant populations are of practical importance. However, these differences may vary considerably, depending on the conditions under which the animals are maintained and fed or on the agrotechnical conditions under which plants are grown, as well as the breeding methods used. The value of h² cannot be absolutely precise, but the important thing is whether the value is large, medium, or small because the value of h² makes it possible to evaluate both the genetic structure of a population and the methods of selection needed to achieve the best results.

REFERENCES

Nikoro, Z. S. , and P. F. Rokitskii. “Primenenie i sposoby opredeleniia koeffitsienta nasleduemosti.” Genetika, 1972, vol. 8, no. 2.
Rokitskii, P. F. Vvedenie ν statisticheskuiu genitiku. Minsk, 1974.
Falconer, D. S. Introduction to Quantitative Genetics. Edinburgh-London, 1960.

P. F. ROKITSKII

heritability

her·i·ta·bil·i·ty

(her'i-tă-bil'i-tē), 1. In psychometrics, a statistical term used to denote the extent of variance of a person's total score or response that is attributable to a presumed genetic component, in contrast to an acquired component. 2. In genetics, a statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h². [see heredity]

heritability

Genetics The likelihood of suffering from a hereditary disease when the defective gene is in a person's gene pool. See Additive genetic variance, Genetic variance, Phenotypic variance, Population.

her·i·ta·bil·i·ty

(her'i-tă-bil'i-tē) 1. psychometrics A statistical term used to denote the extent of variance of a subject's total score or response that is attributable to a presumed genetic component, in contrast to an acquired component. 2. genetics A statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h².

heritability (h2)

the proportion of all phenotypic variance in a population that is due to genetic differences and which can be assessed in terms of two main ways, BROAD-SENSE HERITABILITY and NARROW-SENSE HERITABILITY. Heritability is thus a general measure of genetic variation without which SELECTION (both natural and artificial) could not proceed, and is used widely by plant and animal breeders to predict the likely effect of selection. For example, if heritability values for a character are low this indicates high environmental variability, and suggests that the response to selection would not be very rapid.

her·i·ta·bil·i·ty

(her'i-tă-bil'i-tē) In genetics, a statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h².

Patient discussion about heritability

Q. Is Autism hereditary? My 3 year old son has been diagnosed with autism last year. I am now pregnant with my second child and am scared that he will too have autism.A. There is a higher chance that your additional children will have autism too, however its not a given. Be more alert and notice any early signs that your child may develop.

Q. Is Leukemia hereditary? My Grandpa died of Leukemia when he was 50. I am worried that it might be hereditary. Is it?A. Overall leukemia is not hereditary but there are rare reports of family clusters, that is, more than one case in a family. Therefore, you should consult your Doctor and tell him about your family's medical history.

Q. Is migraine hereditary? If both my parents suffer from migraines does it mean I can't avoid it?A. Yes, migraines do have a very strong genetic correlation. However, it does not mean that if both your parents have it, you will have it too for 100%. It means only that you have a much higher risk than the regular population, that does not have migraines in their family, to suffer from this condition.

More discussions about heritability

单词	heritability
释义	heritability her·i·ta·ble H0162900 (hĕr′ĭ-tə-bəl)adj.1. Capable of being passed from one generation to the next; hereditary.2. Capable of inheriting or taking by inheritance. [Middle English, from Old French, from heriter, to inherit, from Late Latin hērēditāre; see inherit.] her′i·ta·bil′i·ty n.her′i·ta·bly adv. Translations ereditarietà Heritability heritability [‚her·əd·ə′bil·əd·ē] (genetics) In a population, the ratio of the total genetic variance to the total phenotypic variance. Heritability the degree to which the phenotypic variation of any trait in a population of animals or plants (or group of them) is determined by the genotypic differences among individuals. The term “heritability” was introduced in 1939 by the American geneticist J. Lush. The total variation in a population is the total result of genotypic variation and the variation caused by environmental factors. Since the degree of variation can be measured by variance (that is, the square of the mean of the square deviation of the variants from the mean of the variational series), the population-genetic parameter h², or the coefficient of heritability, is used to characterize heritability. The formula in the broad sense is: where σp² is the total phenotypic variance, σg² is the genotypic variance determined by the genotypic differences among individuals, and σE² is the variance caused by fluctuations in the environment. h₁², the coefficient of heritability in the narrow sense, is also distinguished: h₁² = σA²/σp2; in this case account is taken not of the entire genotypic variation but only of one of its components σA², the variance determined by the differences in the additive genes (the effect of these genes on a trait is summed arithmetically). The σA² index is important for selection because selection is achieved mainly through additive genes or polygenes. The values of h² and h₁² are expressed in fractions of less than 1, less often in percent. The special methods available for determining h² are based chiefly on establishing the phenotypic resemblance among individuals related to different degrees for which correlation, regression, and other factors are used. The coefficient of heritability applies only to populations and not to individuals. The values of h² depend on the nature of the trait studied. For example, the traits associated with reproduction have fairly low h² (for example, h² of fertility in sheep, pigs, and mice is 0.1–0.2), whereas constitutional traits are fairly high h² (h² of head length in cattle is 0.6–0.7, and h² of skin folds in sheep 0.5–0.8). The differences between h² of economically useful traits in specific herds of breeding animals and plant populations are of practical importance. However, these differences may vary considerably, depending on the conditions under which the animals are maintained and fed or on the agrotechnical conditions under which plants are grown, as well as the breeding methods used. The value of h² cannot be absolutely precise, but the important thing is whether the value is large, medium, or small because the value of h² makes it possible to evaluate both the genetic structure of a population and the methods of selection needed to achieve the best results. REFERENCES Nikoro, Z. S. , and P. F. Rokitskii. “Primenenie i sposoby opredeleniia koeffitsienta nasleduemosti.” Genetika, 1972, vol. 8, no. 2. Rokitskii, P. F. Vvedenie ν statisticheskuiu genitiku. Minsk, 1974. Falconer, D. S. Introduction to Quantitative Genetics. Edinburgh-London, 1960. P. F. ROKITSKII heritability her·i·ta·bil·i·ty (her'i-tă-bil'i-tē), 1. In psychometrics, a statistical term used to denote the extent of variance of a person's total score or response that is attributable to a presumed genetic component, in contrast to an acquired component. 2. In genetics, a statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h². [see heredity] heritability Genetics The likelihood of suffering from a hereditary disease when the defective gene is in a person's gene pool. See Additive genetic variance, Genetic variance, Phenotypic variance, Population. her·i·ta·bil·i·ty (her'i-tă-bil'i-tē) 1. psychometrics A statistical term used to denote the extent of variance of a subject's total score or response that is attributable to a presumed genetic component, in contrast to an acquired component. 2. genetics A statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h². heritability (h2) the proportion of all phenotypic variance in a population that is due to genetic differences and which can be assessed in terms of two main ways, BROAD-SENSE HERITABILITY and NARROW-SENSE HERITABILITY. Heritability is thus a general measure of genetic variation without which SELECTION (both natural and artificial) could not proceed, and is used widely by plant and animal breeders to predict the likely effect of selection. For example, if heritability values for a character are low this indicates high environmental variability, and suggests that the response to selection would not be very rapid. her·i·ta·bil·i·ty (her'i-tă-bil'i-tē) In genetics, a statistical term used to denote the proportion of phenotypic variance due to variance in genotypes that is genetically determined, denoted by the traditional symbol h². Patient discussion about heritability Q. Is Autism hereditary? My 3 year old son has been diagnosed with autism last year. I am now pregnant with my second child and am scared that he will too have autism.A. There is a higher chance that your additional children will have autism too, however its not a given. Be more alert and notice any early signs that your child may develop. Q. Is Leukemia hereditary? My Grandpa died of Leukemia when he was 50. I am worried that it might be hereditary. Is it?A. Overall leukemia is not hereditary but there are rare reports of family clusters, that is, more than one case in a family. Therefore, you should consult your Doctor and tell him about your family's medical history. Q. Is migraine hereditary? If both my parents suffer from migraines does it mean I can't avoid it?A. Yes, migraines do have a very strong genetic correlation. However, it does not mean that if both your parents have it, you will have it too for 100%. It means only that you have a much higher risk than the regular population, that does not have migraines in their family, to suffer from this condition. More discussions about heritability ThesaurusSeeheritable
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heritability

her·i·ta·ble

Heritability

heritability

Heritability

REFERENCES

heritability

her·i·ta·bil·i·ty

heritability

her·i·ta·bil·i·ty

heritability (h2)

her·i·ta·bil·i·ty

Patient discussion about heritability