BIOL 202 Lecture Notes - Backcrossing, Gene Flow, Heritability
21 May 2012
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Document Summary
In reality, the phenotypic changes observed in nature are more gradual and complex than the single, discrete changes we see with classical mendelian genetics. Most of the complex traits are controlled by many different genes, which results in their being a large variance in the types of phenotypes we observe. Therefore, quantitative genetics is the study of these polygenic traits. Quantitative genetic variation can be described in three ways: Traits are influenced by multiple genes, i. e. they"re polygenic. They are usually influence more easily by environmental factors than simple mendelian traits. Both of the factors above usually lead to a continuous distribution of the particular trait: for example, you can see the near normal, or continuous, distribution to the right when comparing a sample population by their height. There are many samples of these traits as most traits in genetics actually do involve multiple genes.
