Lecture 17 Summary of Natural Selection

Lecture 17 Summary of Natural Selection - Natural Selection...

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NATS 1690 - Natural Selection 1 Natural Selection - Summarized
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NATS 1690 - Natural Selection 2 References Custom Textbook – An Introduction to Biological Evolution , 2009 Pages 70 – 85 These lecture notes
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NATS 1690 - Natural Selection 3 Darwin’s main ideas about natural selection can be summarized in 3 points 1. Natural selection is observed as differential success in reproduction Unequal ability of individuals to survive and reproduce 2. Natural selection occurs through an interaction between a. The environment b. The variability inherent among the individual organisms making up a population 3. The result of natural selection is the “adaptation of populations ” of organisms to their environment How does natural selection work? http://www.pbs.org/wgbh/evolution/library/11/2/e_s_4.html (6.4 minutes)
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4 Example : related species of insects called mantids have diverse shapes & colors that evolved in different environments http://www.pbs.org/wgbh/evolution/library/01/1/l_011_03.html (1 minute)
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NATS 1690 - Natural Selection 5 5 observations – led to 3 inferences… Tremendous fertility Stable population sizes Limited environmental resources Variation among individuals Heritability of some of this variation
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NATS 1690 - Natural Selection 6 Observation #1: Tremendous Fertility All species have great potential fertility Their population size would increase exponentially (2, 4, 8, 16, 32, 64,…) IF ALL individuals that are born reproduced successfully Observation #2: Stable population sizes Natural populations tend to remain stable in size , except for seasonal fluctuations Observation #3: Limited environmental resources Environmental resources are limited – thus cannot
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Lecture 17 Summary of Natural Selection - Natural Selection...

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