BIOL 2040 Lecture Notes - Lecture 9: Heritability, Disruptive Selection, Stabilizing Selection
13 Feb 2016
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A line cross in tobacco: cross long x short. F2 is also intermediate, but with greater variance: if the 2 extremes of f2 were bred, could get offspring similar to parents. Many characteristics not entirely determined by genotype: same genotype can produce multiple varying phenotypes. Ex. plants with the same genotype grown in 3. Affected by environment raised in different environments. Genetic and environmental variance o o: phenotypic variance. Result from cumulative effects of multiple loci. Adds one unit to the size of the trait: additive model simplest model: each upper case allele. Imagine lower case alleles either decrease a trait or add less to a trait than upper case alleles. Ex. lower case allele makes corolla 10mm shorter, and upper case makes 10mm taller. Each upper case allele adds one unit (10mm) to the size of the trait. Few individuals on extreme ends of trait spectrum. Heritability is high if individuals with same genotypes have very.
