BIO 370 Lecture Notes - Lecture 11: Brachydactyly, Allele Frequency, Population Genetics
The Genetics of Populations
Critis attaked Medel’s olusios o ultiple grouds
• Medel’s results did ot see to eplai ariatio i otiuousl ariale traits.
• That such traits were usually controlled by multiple loci and the consequences
thereof was not understood.
• Later in the course
• Mendelian inheritance did not explain frequency of observed discrete traits in nature.
• Early criticisms were grounded in transmission genetics rather than population
genetics.
It was unclear whether a Mendelia sste of iheritae ould e osistet ith Dari’s
theory of evolution by natural selection.
E.g., a cross of 2 heterozygotic parents produces offspring in the typical 3:1 ratio (transmission
genetics).
Steeped in transmission genetics thought, some concluded that dominant traits should also
approach 3:1 ratios in nature.
The genetics of brachydactyly illustrate the difference between transmission genetics and
population genetics.
Brachydactyly is a malformation of the fingers.
Inherited as a single locus and two alleles (B and b, where B is dominant, producing the
malformation.)
BB and Bb individuals have brachydactyly.
Children of Bb x Bb
parents exhibit
brachydactyly in a
3:1 ratio.
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Document Summary
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