L41 BIOL 2970 Lecture Notes - Lecture 32: Quantitative Trait Locus, Quantitative Genetics, Total Variation
13 Nov 2017
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Quantitative genetics: analysis of genetic variance for continuous phenotypes -- ronald a. fisher. Polygenic inheritance -- phenotype is controlled by variation at a large number of different genes that each contribute a minor amount to the total variation. Environmental variation -- interaction with environmental conditions that influence expression of the phenotype. These two are not mutually exclusive -- in most cases both are invoked. In additive inheritance, there is no dominant condition. The capital allele is treated as adding additively to the phenotype. The heterozygous condition is exactly in between the two extremes. As the number of loci that influences the trait gets larger and larger, each individual locus. As the number of loci that influences the trait gets larger and larger, each individual locus contributes a smaller proportion of the total variation, so the categories become more continuous. When there are few loci, the categories are rather distinct. Area under the curve = frequency of genotype in the population.
