Chapter 20 - Chapter 20 Genes within Populations I. Genes...

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Chapter 20 Genes within Populations I. Genes vary in natural populations 1. Genetic variation is the basis of evolutionary change 2. Evolution = change in the genetic makeup of a population over time. 3. How does evolution occur? 4. Darwin was not the only person who proposed evolution among organisms A. Jean Baptist Lamark (1802) Inheritance of acquired characteristics Use and disuse B. Charles Darwin – Descent with modification “Natural Selection” 1. Organisms produce more offspring than will survive 2. Populations are highly variable 3. Variability is inherited 4. Resources are limited so there is a struggle to survive 5. Animals best adapted survive and reproduce 6. Inherited traits become more prevalent in the population Darwin
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*It is now known that natural selection is not the only mechanism of change in a population’s genetic makeup II. How does genetic variation arise? A. Mutation = ultimate source of variation B. Crossing over and random assortment in meiosis C. sexual reproduction results in new genetic combinations
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Chapter 20 - Chapter 20 Genes within Populations I. Genes...

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