Calculate broad-sense (H²) and narrow-sense (h²) heritability coefficients from genetic variance, phenotypic variance, and twin correlations to estimate trait inheritance patterns.
Heritability Coefficient
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Heritability Percentage
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Environmental Variance (Ve)
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Interpretation
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Broad-sense heritability (H²) measures the proportion of total phenotypic variance due to all genetic factors, while narrow-sense heritability (h²) measures only the additive genetic effects that are passed from parents to offspring.
Heritability values range from 0 to 1. A value of 0.8 means 80% of the variation in a trait is due to genetic factors, while 20% is environmental. Higher values indicate stronger genetic influence on the trait.
Twin studies use correlations between monozygotic (identical) and dizygotic (fraternal) twins. The formula is h² = 2(rMZ - rDZ), where rMZ is the correlation for identical twins and rDZ is the correlation for fraternal twins.
No, heritability cannot exceed 1.0 by definition, as it represents a proportion of variance. Values above 1.0 indicate calculation errors or invalid input parameters.
Environmental variance (Ve) represents the portion of phenotypic variation caused by environmental factors rather than genetics. It equals total phenotypic variance minus genetic variance (Ve = Vp - Vg).
Heritability estimates are population-specific and environment-specific. They represent the proportion of variance in a particular population under specific conditions, not the absolute genetic contribution to a trait.
Breeding response (R) is the change in trait mean after selection. It relates to heritability through the formula h² = R/S, where S is the selection differential (difference between selected parents and population mean).