3. 05 Examine the development of the theory of evolution by natural selection including: development of the theory, the origin and history of life, fossil and biochemical evidence, mechanisms of evolution

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3.05 Examine the development of the theory of evolution by natural selection including: development of the theory, the origin and history of life, fossil and biochemical evidence, mechanisms of evolution, and applications (pesticide and antibiotic resistance).

92. In the following chart, describe the role of each of the following in developing the current theory of evolution.

Discussion of importance to evolutionary theory

Understanding of geology

(Changes in the earth)

That the early has been constantly changing, why not living things?

Malthus’ ideas about population


Humans (perhaps like other organisms) are limited by environmental pressures (disease, resources, space, etc)

Anatomical comparisons

Animals that share common characteristics in bone structure may have had some form of common ancestry.

Patterns in fossil evidence

Ancient organisms adapted and responded to their environment by inheritable characteristics depending on the type of environment.

Lamarck’s ideas about inheritance

Of acquired characteristics

He believed that animals inherited characteristics based upon their use and disuse of traits which is not true, but raised the issue of how they were they passed on?

Biochemical comparisons

(DNA and proteins)

By directly comparing DNA and proteins, scientists can determine when animals diverged from one another as well as compare their evolutionary relationships.

The role of variations

Animals seemed to adapt to their particular environments. Why?

The role of sexual reproduction

Animals that sexually reproduced had more success (fitness) in a changing environment. Why was this?

The role of geographic isolation

When animals are separated geographically, major adaptations occurred. Why?

The importance of the


A constant theme in whether or not animals survived or went extinct was their natural environment. How did this shape how animals survived then and today?

93. What is a vestigial structure? Name a few in humans. A structure that is no longer useful to an organism, but may have been used by ancestors. Vestigial structures in humans include the coccyx (tail bone), ear muscles, appendix, and goose bumps from getting scared.

94. What are some of the ideas on the origins of life? (A.k.a. where and when did it form?) Life likely formed in the Earth’s oceans where it was constant and safe from the toxic, oxygen deprived atmosphere and harsh land conditions. As cyanobacteria produced oxygen and the climate changed that the oceans dried up (not totally!), animals and plants began to move the land environment and develop complexity from simple carbon molecules to amino acids, protocells and cells.

95. Discuss the steps in Darwin’s theory of evolution by natural selection. (Chapter 15)

1) Populations of organisms have many genetic variations. Where do these come from? Inherited genes seen fit by those best suited to the environment who could find food and a mate to pass those on to their offspring.

2) Organisms could reproduce exponentially but they don’t. Why not? What are they restricted by? No, they are restricted by food availability, space and mate selections. The best suited to the environment will survive & reproduce.

3) What are adaptations? Any inherited characteristic that increases an organism’s chance of survival.

4) Some adaptations have better survival value in certain environments. What does this mean? Some adaptations (based upon genotypic mutations) are not favorable for that particular environment. They are not selected for and that particular organism dies and does not pass on that particular adaptation to their offspring.

5) What does it mean to be “fit” to an environment? The ability of an individual to survive and reproduce in their particular environment.

6) The next population will have a high frequency of the genes that have been selected for. Why will the frequency of selected genes increase? Those who are fit will be the only ones to survive and reproduce passing on those genes.

7) What is Darwin’s theory of Natural Selection? What is Artificial Selection? In natural selection, only the fittest will survive to produce offspring for the next generation (survival of the fittest.) In artificial selection, humans select organisms for desired traits and ensure breeding (plus survival) so those traits is present in their offspring. Such as particular dog breeds that could never survive in the natural environment.

8) When this process continues over millions of years, it can lead to speciation. What is speciation? When members of a species evolve they split and become reproductively isolated from one another. This creates two new species.

96. Compare and contrast convergent and divergent evolution. Convergent evolution is when two generally unrelated species in different areas adopt similar adaptations based upon a common environment. Divergent evolution is when animals diverge from each other then they geographically adopt different areas and must take on different characteristics as adaptations in order to survive, becoming more different than one another.

97. Sketch or describe the following: Stabilizing Selection, Directional Selection and Disruptive Selection.

Stabilizing Selection – When individuals at the phenotypic extremes are selected against and those in the middle are selected for. Creates a species more uniform, towards the average. (Bell Shaped Curve)

Directional Selection – When individuals at one phenotypic extreme are selected for and those in the middle or other extreme are selected against. Creates one type of species slanted in that direction. (Directional Curve)

Disruptive Selection – When individuals at each phenotypic extreme are selected for and those in the middle are selected against. Creates two new species (speciation) to form. (Disruptive Shaped Curve)

98. What is adaptive radiation? How did the finches of the Galapagos adapt to their environment?

Adaptive radiation is a type of divergent evolution where groups based upon new environments adapt differently creating new species. Darwin’s finches adapted according to their food source and was reflected in their type of beak.

99. Describe how a population of bacteria can become resistant to an antibiotic (or an insect to a pesticide) using the steps listed above. How is this a direct way to observe evolution? Bacteria that have natural mutations to survive a particular insect or pesticide have new space and resources to survive and reproduce creating a new generation resistant to that particular obstacle.

100. What happens when pesticides and antibiotics are used and how does it relate to evolution? When one particular antibiotic is used frequently, populations evolve (see question 99) a natural immunity to it. This is the exact theory of Darwin’s survival of the fittest.

101. What are the differences between abiogenesis (spontaneous generation) and biogenesis? In abiogenesis life can arise from nothing, even air. In biogenesis, life must arise from other living life.

102. What did Louis Pasteur contribute to our understanding of the origins of life? Louis Pasteur described through his curved flask experiment that life cannot come simply from air but through other living things, such as molecules that we cannot see (microorganisms).

103. Why did Miller and Urey put those particular gases into their experiment? They were found in the early Earth’s atmosphere where life would have likely started.

104. What type of organic molecules did they find? Amino acids

105. What is the significance of their experiments? Amino acids are the monomers or building blocks of proteins that make up organisms or life.

106. Most hypotheses state that prokaryotic anaerobes probably evolved first. Why?

Because there was no oxygen in the early Earth’s atmosphere.

107. The hypotheses then suggest that prokaryotic autotrophs probably evolved? Why? They were the ones (i.e. cyanobacteria) that produced the oxygen that is found in our atmosphere today.

108. What gas would enter the atmosphere as a result of these autotrophs appearing. OXYGEN!

109. Then prokaryotic aerobic heterotrophs could evolve. What can these cells do that others before them cannot? Synthesize organic materials into energy. Before then there was only the SUN to use energy.

110. What is the hypothesis explaining how eukaryotic cells evolved? Endosymbiont theory (Lynn Margulis)

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