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Modern Genetic Analysis
18. Quantitative Genetics
Key Concepts

In natural populations, variation in most characters takes the form of a continuous phenotypic range rather than discrete phenotypic classes. In other words, the variation is quantitative, not qualitative.
Mendelian genetic analysis is extremely difficult to apply to such continuous phenotypic distributions, so statistical techniques are employed instead.
A major task of quantitative genetics is to determine the ways in which genes interact with the environment to contribute to the formation of a given quantitative trait distribution.
The genetic variation underlying a continuous character distribution can be the result of segre-gation at a single genetic locus or at numerous interacting loci that produce cumulative effects on the phenotype.
The estimated ratio of genetic to environmental variation isnot a measure of the relative contri-bution of genes and environment to phenotype.
Estimates of genetic and environmental variance are specific to the single population and the particular set of environments in which the estimates are made.

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