AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

VARIANCE

• The differences in phenotypic values of quantitative traits among individuals of a population are referred to as variation.
• The amount of variation is measured and expressed as variance. Variance measures the variability from an average or mean.
• The basic idea in the study of variance is its partitioning into components attributable to different causes.
• If there is no genetic variation then there is no scope for improvement.
• The components into which the phenotypic variance is partitioned are the same as the components of phenotypic value described earlier.

• The relative magnitude of variance components is determined by the degree of resemblance between relatives.