Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 143

Population genetics and quantitative genetics are closely related fields, both dealing with the genetic basis of phenotypic variation among the individuals in a population. Population genetics traditionally focuses on frequencies of alleles and genotypes, whereas quantitative genetics focuses on linking phenotypic variation of complex traits to its underlying genetic basis to enable researchers to better understand and predict genetic architecture and long‐term change in populations (to predict the response to selection given data on the phenotype and relationships of individuals in the population). Historically, quantitative genetics has its roots in statistical abstractions of genetic effects, first described by Karl Pearson and Ronald Fisher in the early 1900s. The foregoing represents the classical view of quantitative genetics.

The modern molecular view of quantitative genetics focuses on the use of molecular genetics tools (genomics, bioinformatics, computational biology, etc.) to reveal links between genes and complex phenotypes (quantitative traits). Genes that control quantitative traits are called quantitative trait loci (QTL). Molecular‐based QTL analyses are being used to evaluate the coupling associations of the polymorphic deoxyribonucleic acid (DNA) sites with phenotypic variations of quantitative and complex traits and analyze their genetic architecture. There is evidence of a paradigm shift in the field of quantitative genetics. In this chapter, both classical (Sections 4.2–4.2.19) and molecular (Sections 4.3–4.7) quantitative genetics are discussed. Discussions in this section will include genetic and environmental variances, relationships and genetic diversity, linkage, and epistatic issues in populations.