Chapter 15 Principles of Evolution

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Chapter 15 Principles of Evolution
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Summary of Darwins Observations and Conclusions
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What is Evolution?

• The definitionBiological evolution, simply put,
  is descent with modification.
• Evolution helps us to understand the history of
  life.

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• The explanationBiological evolution is not
  simply a matter of change over time. Lots of
  things change over time trees lose their leaves,
  mountain ranges rise and erode, but they aren't
  examples of biological evolution because they
  don't involve descent through genetic
  inheritance.

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• The central idea of biological evolution is that
  all life on Earth shares a common ancestor, just
  as you and your cousins share a common
  grandmother.

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• Through the process of descent with modification,
  the common ancestor of life on Earth gave rise to
  the fantastic diversity that we see documented in
  the fossil record and around us today. Evolution
  means that we're all distant cousins humans and
  oak trees, hummingbirds and whales.

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Evidence for evolution comes from geology and the
fossil record. These are examples of fossils
from different time periods. Each layer of rock
represents a different time period in earths
history.
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Darwins Finches demonstrate that organisms can
change over time. Adaptations best suited for a
particular environment become more common in
offspring.
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Fossil record of the Evolution of the Horse.
Notice the leg and tooth morphology
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Convergent Evolution leads to Analogous
Structures. Organisms in the same environment
tend to develop similar structures and look
similar even though they are distantly related.
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Another example of Convergent Evolution. Notice
the body shape and coloring
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Divergent Evolution leads to Homologous
structures. The swallow and the penguin are both
birds, but they live in different environments.
The swallow is more closely related to the
penguin even though it may look more like the
mayfly.
Even though the penguin looks more like the seal,
it is more closely related to the swallow.
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More homologous structures among
vertebrates. Notice the basic bone pattern but
different functions Darwins Theory suggests such
similar bone patterns were due to a common
ancestor.
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• Vestigial Structures are evidence of common
  ancestry.
• Vestigial structures in humans include
• Wisdom teeth
• Appendix
• The muscle that wiggles your ears
• The gene that codes for the production of Vitamin
  C

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Artificial selectionIf humans can
select traits of offspring, Why cant Nature?
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More examples of artificial selection Dogs from
wolves Corn from teosinte