Ch06 Lecture (1) - 6 Evolution and Ecology What Is...

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6 Evolution and Ecology
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What Is Evolution? Concept 6.1: Evolution can be viewed as genetic change over time or as a process of descent with modification. Evolution strictly is change in allele frequency (proportion) over time.
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What Is Evolution? Example: In a population of 1,000, 360 are AA , 480 are Aa , 160 are aa . Frequency of a is 0.4 or 40%; frequency of A is 0.6 or 60%. If the frequency of a changed to 71%, the population would have evolved at that gene.
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Figure 6.3 Descent with Modification
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Mechanisms of Evolution Four key processes influence evolution: Mutation (provides raw material for evolution) Natural selection (includes human causes) - Three types Genetic drift Gene flow Concept 6.2: Natural selection, genetic drift, and gene flow can cause allele frequencies in a population to change over time.
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Figure 6.6 A Three Types of Natural Selection
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Figure 6.6 B Three Types of Natural Selection
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Figure 6.6 C Three Types of Natural Selection
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Mechanisms of Evolution Genetic drift is significant only for small populations.
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