7 - lecture handout - BIOLOGY 325H Quantitative Genetics...

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BIOLOGY 325H Quantitative Genetics January 30, 2008 Genes are discrete, integer-value entities. We count them in whole numbers. There is no such thing as a half-gene or quarter-gene. And some traits in an organism are similarly discrete, like Mendel’s wrinkled and round peas. In these cases, we can see how the combinations of alleles at a locus or alleles at a small number of loci create the categories into which a trait falls. Yet, many traits vary continuously. So how do discrete entities like genes produce traits that take on a continuous range of values rather than discrete classes of values? And when a trait is produced by many genes, how can we understand how selection will operate on that trait and its genes, especially when we don’t know precisely (if at all) what the genes are that produce the trait and what the individual influence of each gene is on the trait? This is the business of quantitative genetics, understanding how a continuous trait can arise and how selection will affect its evolution. The key to the production
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This note was uploaded on 05/14/2008 for the course BIO 325H taught by Professor Staff during the Spring '08 term at University of Texas at Austin.

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