BIOL 2030 Lecture Notes - Lecture 10: Quantitative Trait Locus, Quantitative Genetics, Polygene
13 Feb 2016
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Phenotypic traits: discontinuous or qualitative traits, only a few distinct phenotypes. Seed colour, pea shape, blood groups: for many discontinuous traits, there is a simple relationship between genotype and phenotype. Each genotype produces a single phenotype: environment has very little influence, even in presence of epistasis, relationship between genes and trait. Able to infer genotype from phenotype remain simple: continuous/quantitative traits, traits for which there is a continuum of possible phenotypes. Often observed in a normal (bell curve) distribution: ex. Height, growth rate, iq, metabolic rate: truly continuous traits. Phenotype can take any value between extremes. Number of offspring, number of vertebrae: meristic traits, threshold traits code. Traits have only 2 phenotypes, but have underlying polygenic. Affected vs. not affected by a disease: can be affected more severely than other"s that are affected, but you are still under the affected phenotype.
