Unit 10 Evolution

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Unit 10 Evolution

• Evolution is defined as a change over time, it is
  the process by which modern organisms have
  descended from ancient organisms
• The Evolutionary Theory which is based upon a
  collection of scientific facts, observations, and
  hypotheses attempts to explain how life on earth
  has become so diverse.

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Voyage of the Beagle

• 1.Charles Darwin contributed more to our
  understandings of evolution than anyone else.
• 2.Born in England, he was a naturalist, and
  sailed with the crew of the
• H.M.S. Beagle in 1831.
• 3.Although no one knew it at the time, this was
  to be one of the most important voyages in the
  history of science.

1809-1882
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 Darwins Voyage
During his voyage Darwin made many stops where he
collected specimens and made many very important
observations about how life changes over time.
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Living Organisms and Fossils
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• 1.Darwin collected preserved remains of ancient
  organisms called fossils.
• 2.As Darwin studied fossils, He noticed that some
  resembled organisms that are alive today and
  others looked completely different.

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• Darwins Observations
• Darwin noticed that of all the plant and animal
  species that he collected, most were well suited
  to the environment that they inhabited.
• Darwin also noticed that biomes with very similar
  environments contained totally different animals.
  
• For example, he visited grasslands in Argentina
  and Australia and noticed that both had entirely
  different animals.

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Giraffe Australia
Mara Argentina
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The Galapagos Islands

• 1. A group of small islands located
• 1000 km west of South America.
• 2. Darwin noted that although they were close
  together, the islands had very different
  climates.
• 3. Darwin was fascinated in particular
• by the land tortoises
• and finches that lived
• in the Galapagos.

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Giant Tortoises of the Galápagos Islands
The shells of the tortoises on each island was
different.
Pinta
Pinta IslandIntermediate shell
Isabela
Hood
Hood Island Saddle-backed shell
Isabela Island Dome-shaped shell
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Galapagos Finches Darwin also noticed that
finches on each island had different beaks.
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Darwin Presents His Case
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• 1.)Darwin returned to England in 1836, he brought
  back specimens from around the world.
• 2.)Darwin began filling notebooks with his ideas
  about species diversity and the process that
  would later be called evolution.
• 3.)In 1859,
• Darwin published his book,
• The Origin of Species

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Natural Selection The driving force behind
evolution !

• 1.)Darwin realized that high birth rates and a
  shortage of lifes basic needs would eventually
  force organisms into competition for resources.
• 2.)The struggle for existence means that members
  of each species compete regularly to obtain food,
  living space, and other necessities of life.
• 3.)A key factor in the struggle for existence is
  how well suited an organism is to its
  environment. Those organisms best suited to the
  demands of the environment will be naturally
  selected by the environment and will go onto
  reproduce new
• offspring with the same adaptations as the
• parents.

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Evidence of Evolution
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• Darwin argued that living things have been
  evolving on Earth for millions of years.
• Evidence to support his hypothesis is found in
• 1.Fossil record
• 2.Geographical distribution of living species
  3.Homologous structures of living organisms
  4.Similarities in early embryonic development

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1. Fossil Record
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• Sedimentary rocks are the most common rocks at
  Earths surface. The buried plant and animal
  remains become fossils within the sedimentary
  layers.

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The position of fossils within rock layers also
can indicate their age. By examining the fossil
record fossils have shown the appearance of
different structures over time.
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Geographic Distribution of Living Species
M U S K R A T
B E A V E R
North America
South America
Coypu
Capybara
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How is it evidence of Evolution? 1. The beaver
and muskrat in North America have very similar
features and behaviors with the coypu and
capybara of South America. 2. Evidence would
suggest that these animals have evolved from a
common ancestor as they moved over a larger area.
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Homologous Body Structures
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• Homologous structures are structures that have
  been modified over time through the process of
  evolution. They have similar structure, but
  different functions.

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Similarities in Early Embryonic Development
An embryo is an organism in its early stages of
development
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