Anthro Lecture 1-17 - Anthro 7 Lecture 1/17 I Forces of...

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Anthro 7 Lecture 1/17 I. Forces of evolution a. Natural selection (non-random differential propagation of alleles) b. Mutation (the rare spontaneous change of one allele to another) c. Gene flow (migration) d. Genetic drift (sampling error) II. Modern Synthesis a. Explains: i. Continuous variation in traits ii. How variation is maintained even when selection is strong iii. How selection can move a species outside its original range of variation III. Most traits are polygenic – affected by >1 locus a. Consider a trait, body size, affected by 10 loci, each with two alleles b. Filled-in alleles promote larger body size c. More filled-in alleles >> larger body size d. Variation is continuous, and is maintained even in the face of strong selection e. At every locus, selection maintains both the large-body-size and the small- body-size alleles at roughly equal frequencies IV.How could natural selection move a population beyond original range of variation? a. Chihuahaus b. The solution to the problem is hidden variation i. Normal sized wolves carry some alleles for small body size (-) and many (+) alleles ii. People bred smaller size in earliest domestic dogs, frequency of (-) alleles is increased
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iii. Finally, recessive genes are mostly sheltered from selection, producing more hidden variation c. Resolves Darwinian selection and Mendellian genetics V. Molecular genetics a. Chromosomes consist of DNA b. DNA is a long double-stranded molecule c. Each nucleotide includes a base which is A, T, G or C d. A pairs with T, G pairs with C VI.DNA replication a.
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