Chapter 4 - Witnessing Change

Notes for Evolution - The Triumph of an Idea - Chapter 4

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Chapter 4 - Witnessing Change - Genes, Natural Selection, and Evolution in Action

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Introduction

Featured Scientist: Gregor Mendel
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Links: 1 - 2 - 3 - 4

For much more extensive coverage of Mendel and genetic inheritance see Understanding Evolution Ch. 3.

I. Introduction

RQ Ev-4.1: In what ways (if any) did not knowing about how traits are inherited limit Darwin in what he could conclude about his proposed mechanism of natural selection?

II. Heredity's Monk

Key Terms: deoxyribonucleic acid

RQ Ev-4.2: In what ways (if any) did not knowing about DNA and how proteins are encoded limit Mendel in what he could conclude about his proposed mechanism of inheritance?

RQ Ev-4.3: Briefly summarize, at a 9th-grade level, how information in "the genes" becomes expressed in "the phenotype."

III. Rewriting Life's Cookbook

For much more extensive coverage of mutations see Understanding Evolution Ch. 4.

RQ Ev-4.4: Briefly describe the role mutations play in evolution, compared with other factors such as sexual recombination and natural selection. When a mutation occurs, has evolution taken place?

RQ Ev-4.5: In the example in Zimmer, how could a cross between two smooth hybrid pea plants (heterozygotes for smooth and wrinkled alleles) end up with all four progeny being wrinkled phenotypes?

IV. The Modern Synthesis

For much more extensive coverage of Dobzhansky's contributions see Understanding Evolution Ch. 6.

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Featured Organism: Drosophila pseudoobscura
Links: 1 - 2 - 3

Drosophila spp. (other species in same genus)
Links: 1 - 2 - 3 - 4

Featured Scientist: Theodosius Dobzhansky
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Links: 1 - 2 - 3 - 4 - 5 - 6

RQ Ev-4.6: How did Dobzhansky's studies reveal a previously unknown wealth of natural variation in flies and other organisms, and what were the implications of his discoveries?

RQ Ev-4.7: How did Dobzhansky influence ornithologist, Ernst Mayr, and mammalian paleontologist, George Simpson, in helping them formulate hypotheses of how speciation might normally occur?

V. Bird Beaks and Guppy Lifetimes

Featured Scientist: David Reznick
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Links: 1 - 2 - 3 - 4 (pdf)

For much more extensive coverage of the Galápagos finches see Understanding Evolution Ch. 12.

RQ Ev-4.8: Compare and contrast the studies on guppies by David Reznick and the studies on Galápagos finches by Peter and Rosemary Grant.

VI. How Species are Made

RQ Ev-4.9: The evolutionary tree on p. 89 of Zimmer provides evidence that the Galápagos finches had a single common ancestor, which then radiated into species with different ecological roles, for example, as the warbler finch, as the vegetarian finch, as ground finches, or as tree finches. The "Common Ancestor" labeled on the tree is actually the last common ancestor of the Grassquit and the Galápagos finches, so where on the tree would you place the last common ancestor of the Galápagos finches? What is the "common ancestor"? A bird? Multiple birds? A species? Can you guess how speciation might have occurred once the last common ancestor made it to the Galápagos?

RQ Ev-4.10: Why are the speciation events leading to hundreds of cichlid species in East Africa's Lake Victoria and other nearby "rift" lakes considered to be a rather spectacular example of "adaptive radiation"?

VII. Fighting Colds with Natural Selection

RQ Ev-4.11: Explain how our immune system has a sort of built-in natural selection mechanism for fighting colds and other diseases?:

VIII. Evolution In Silico

RQ Ev-4.12 (Skip): Compare and contrast the approach used in the field of evolutionary computing with real-life evolution in natural populations of organisms.

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