Lecture19_slides_12Oct11 - Ageneticdefinitionofevolution:...

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1 Population Genetics: A genetic view of evolutionary change Genetic change may occur through: • Natural Selection • Genetic Drift A genetic definition of evolution: Evolution is any genetic change in a population. • Migration • Mutation Mutation Ultimate source of genetic variation in a population Mutation causes white mutation evolutionary change (new mutations change allele frequencies), but is a slow and weak process relative to other population genetic forces. normal eye Drosophila melanogaster Natural Selection Organisms face many obstacles to survival and reproduction. “Nature red in tooth and claw…” Advantageous alleles will increase in frequency over time in a population. Gene Flow (Migration) Movement of individuals (and their genes) between populations can cause shifts in allele frequencies. Random Genetic Drift Random events can dramatically alter gene frequencies in populations Populations have finite size, allele frequencies change due to random sampling of genotypes across generations Colorblindness on Pingelap Atoll
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2 Types of mutation point mutations o synonymous o non synonymous regulatory mutations insertions and deletion insertions and deletions aneuploidies polyploidies The book describes different types of mutation in detail. No matter what the type of mutation, the result is a new genetic variant (allele). Recall: Point mutations Pro Leu Tyr Asp Glu CCGCTCTACAACCAG Any mutation that alters a single nucleotide base Point mutations Pro Leu Tyr Asp Glu CCGCT T TACAACCAG Pro Leu Tyr Asp Glu CCGCT C TACAACCAG CTC = Leucine CTT = Leucine Point mutations Pro Leu Tyr Asp Glu CCGCT T TACAACCAG Pro Leu Tyr Asp Glu CCGCT C TACAACCAG Substitutions that do not cause amino acid changes are called silent or synonymous mutations these are frequently assumed to have no functional consequence Point mutations Pro HIS Tyr Asp Glu CCGC A CTACAACCAG
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Lecture19_slides_12Oct11 - Ageneticdefinitionofevolution:...

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