B1510F07_L8_EvolMechanisms_skeleton

B1510F07_L8_EvolMechanisms_skeleton - Georgia Tech School...

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Biology 1510/1511 Georgia Tech School of Biology Fall 2006 Basic Mechanics of Evolution Excess production Populations tend to increase exponentially when most/all offspring survive to adulthood. But most populations are relatively stable in size, so mortality must be important. Genetic variation Individuals often differ significantly in survival and reproductive success. Selection The set of genes passed from one generation to the next is biased toward those carried by the more successful individuals. Natural selection is simply differential success in reproduction. Evolution As long as variation is heritable and not simply due to environmental factors, differential success in survival and reproduction will lead to changes in a population through time. Population of organisms Hereditary variations Differences in reproductive success Evolution of adaptations in the population Overproduction and struggle for existence Campbell & Reece, Fig. 1.2
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Biology 1510/1511 Georgia Tech School of Biology Fall 2006 1. Individuals vary in phenotype, even among close relatives such as siblings 2. Some of this phenotypic variance is due to genetic variance 3. There is a struggle for existence and some phenotypes are better suited to prevailing conditions than others The result: Adaptation – the increase in frequency of well-adapted phenotypes within the population over time Evolution by Natural Selection
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Biology 1510/1511 Georgia Tech School of Biology Fall 2006 Artificial selection The use and utility of artificial selection were common knowledge in Darwin’s day… – selective breeding of livestock and food plants is an ancient technology – breeding fancy forms or animals and flowers was a very common hobby
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Biology 1510/1511 Georgia Tech School of Biology Fall 2006 Columba livia (Rock pigeon)
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Biology 1510/1511 Georgia Tech School of Biology Fall 2006 Columba livia (Rock pigeon) Standing variation
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Biology 1510/1511 Georgia Tech School of Biology Fall 2006
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B1510F07_L8_EvolMechanisms_skeleton - Georgia Tech School...

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