Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 145

The major way in which qualitative genetics and quantitative genetics differ may be summarized as follows:

 Nature of traitsQualitative genetics is concerned with traits that have Mendelian inheritance and can be described according to kind, and as previously discussed, can be unambiguously categorized. Quantitative genetic traits are described in terms of the degree of expression of the trait, rather than the kind.

 Scale of variabilityQualitative genetic traits provide discrete (discontinuous) phenotypic variation, whereas quantitative genetic traits produce phenotypic variation that spans the full spectrum (continuous).

 Number of genesIn qualitative genetics, the effects of single genes are readily detectable, while in quantitative genetics, single gene effects are not discernible. Rather, traits are under polygenic control (genes with small indistinguishable effects).

 Mating patternQualitative genetics is concerned with individual matings and their progenies. Quantitative genetics is concerned with a population of individuals that may comprise a diversity of mating kinds.

 Statistical analysisQualitative genetic analysis is quite straightforward, and is based on counts and ratios. On the other hand, quantitative analysis provides estimates of population parameters (attributes of the population from which the sample was obtained).