DOWN SYNDROME Also known as trisomy 21, is the most common autosomal aneuploidy in humans About 75% of the nondisjunction events that cause Down syndrome are maternal in origin, most arising in meiosis I. 

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#Unit 11. Evolution and Behavior

Relative genotypic frequency after selection

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#Unit 11. Evolution and Behavior

Selection coefficients-  The allelic frequency at equilibrium (qˆ) depends on the relative fitnesses of the two homozygotes:

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#Unit 11. Evolution and Behavior

Positive Selection: The Spread of Beneficial Mutations

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#Unit 11. Evolution and Behavior

Hitchhiking - An allele at one locus spreads by natural selection acting on a second locus that is in linkage disequilibrium with  the first.

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#Unit 11. Evolution and Behavior

Mutation and natural selection act as opposing forces on detrimental alleles.

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#Id: 2179

#Unit 11. Evolution and Behavior

Genetic drift and directional selection will eventually result in fixation of allele.