Natural Selection and the Evidence for Evolution

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Chapter 15.1

• Natural Selection and the Evidence for Evolution

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Charles Darwin and Natural Selection

• Biologist have used fossils in their work since
  the eighteenth century
• Fossil evidence formed the basis of the early
  evolutionary concepts.
• Charles Darwin went on a five year voyage to
  collect different species from around the world.
• Through his observations he noticed that many of
  the same types species had different
  characteristics but were basically the same just
  like breeders of dogs.

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• Artificial Selection Breeding organisms with
  specific traits in order to produce offspring
  with identical traits.
• Darwin hypothesized that there was a force in
  nature that worked like artificial selection.
• After many years of experimentation and
  observation, he proposed the idea that species
  originated through a process of natural
  selection.
• Natural Selection is a mechanism for change in
  populations. It occurs when organisms with
  certain variations survive, reproduce, and pass
  their variations to the next generation.

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Adaptations Evidence for Evolution

• Structural Adaptations
• a. Having body parts that help
  you survive and losing parts that
  you dont need.
• b. Mimicry a structural
  adaptation that enables one species
  to resemble another species.
• c. Camouflage an adaption
  that enables species to blend
  with their surroundings.
• Physiological Adaptations
• a. Physiological adaptations are
  changes in an organisms metabolic
  processes.

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Other evidence for evolution

• Fossils are an important source of evolutionary
  evidence because they provide a record of early
  life and evolutionary history.
• Anatomy
• a. Homologous structures Structural
  features with a common evolutionary origin.
• b. Analogous structures Body parts that
  do not have a common evolutionary origin but
  are similar in function.
• c. Vestigial structure A body structure
  that has no function in a present-day organism
  but was probably useful to an ancestor.

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• Embryology
• a. Embryo is the earliest stage of
  growth and development of both plants and
  animals.
• Biochemistry
• a. Shows that DNA and RNA in
  different species are up to 90 the same
  in plants and animals
• and allowed scientist to develop
  an evolutionary
• diagram of the earths species.