DO NOW

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DO NOW

• When people think EVOLUTION, they often think
  of the phrases Only the strong survive or
  survival of the fittest.
• Based on your reading for homework, what do these
  phrases mean to you?
• How do you think it applies to other species of
  animals besides humans?

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Evolution Changes Through Time
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DARWINS VOYAGE

• Charles Darwin naturalist aboard a ship from
  England that sailed around the world.
• his job was to learn about all the living things
  that he saw on the journey.
• His ship, the HMS Beagle, spent a lot of time on
  a chain of islands called the Galapagos Islands.

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• His observations of living things, fossils, and
  the characteristics of all the organisms he saw
  on the Galapagos islands led to some of the most
  basic theories about evolution

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DARWINS OBSERVATIONS

• While on the voyage Darwin was amazed by the
  variety of living things he saw.
• Today scientists have identified more than 1.7
  million species of organisms and not all living
  things have been identified.
• A species is a group of similar organisms that
  can mate with each other and produce fertile
  offspring.

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Darwins Tools Were Simple

• Magnifying glass
• Glass bottom bucket
• Notebook and pencil
• He observed organisms living on the island as
  well as studied fossils that were left behind
  from long ago.
• Fossil Preserved remains or traces of organisms
  that lived in the past
• Darwin found fossils that were similar to the
  bones of sloths living on the island now, except
  they were much larger. He wondered what happened
  to these giant animals.

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DARWINS OBSERVATIONS

• On the Galapagos Islands Darwin saw the largest
  amount of diversity. He saw giant tortoises,
  sally light-foot crab, blue footed boobies, seals
  covered with fur, and lizards that only ate
  cacti.

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Many of the plants and animals on the islands
were similar to organisms Darwin saw on the
mainland of South America.

• EXAMPLES Birds and plants.

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HOW DID THEY GET THERE?

• Darwin inferred that some species came to the
  islands from the mainland.
• Maybe they were taken there by the ocean
• Once on the islands they reproduced.

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There were also important differences between
organisms on the islands and those on the
mainland.

• Cormorants on the mainland could fly, those on
  the islands could not.
• Iguanas on the islands had large claws and
  iguanas on the mainland had small ones.

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Observe the Claws
Mainland
Galapagos Islands
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There were even differences between the islands!

• The tortoises on one island had dome-shaped
  shells, while on another island they were
  saddle-shaped shells.

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DO NOW - Discussion

• Some insects look just like sticks. How could
  this be an advantage to the insects? How could
  this trait have evolved through natural selection?

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ADAPTATIONS

• Darwin also noticed differences in finches on the
  islands.
• There beaks were suited towards their diet.
• Which two do you think were adapted to eat seeds?
• Which two do you think were adapted to eat
  insects?

Adaptation a trait that helps an organism
survive and reproduce.
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ADAPTATIONS

• Beak shape is an example of an adaptation.

Based on these two pictures, what adaptations do
you see?
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• Darwin studied his observations for many years.
  He thought that the organisms arrived on the
  islands and faced conditions that were different
  from those on the mainland.
• He concluded that the species must have gradually
  changed over generations and became better
  adapted to their new conditions

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EVOLUTION

• The gradual change in a species over time.

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How does the environment select organisms to
survive

• Individuals with helpful variations will allow
  them to survive and reproduce possibly passing
  that helpful allele to their offspring.
• Nature selects the ones with better variations
  while unfavorable variations disappear.

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Natural Selection

• Process by which individuals that are better
  adapted to their environment are more likely to
  survive and reproduce than other members of the
  same species.

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Darwin Hypothesized That There are THREE Factors
that Can Effect Natural Selection

• Overproduction
• Competition
• Variations in the species

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There are many factors that affect natural
selection

• Overproduction Most species produce more
  offspring than could possibly survive.
• Not enough food, water, or living space.

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There are many factors that affect natural
selection

• Competition The offspring must battle
  indirectly with each other to survive.

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There are many factors that affect natural
selection

• Variations Differences between individuals of
  the same species.
• HOW do variations and natural selection work to
  change a species over time?

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Variations acted on by Natural Selection

• Suppose the climate in an area becomes much drier
  than it was before. What kinds of variations in
  the areas plants might be acted on by natural
  selection.

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Can a change in the environment effect survival
of an organism?

• YES!
• An organism more suited for the environment is
  selected by nature to survive, reproduce, and
  pass on its helpful variation.

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Discussion

• When people think EVOLUTION, they often think
  of the phrases, Only the strong survive or,
  Survival of the fittest. How do these phrases
  describe the concept of natural selection?

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Discussion

• Imagine that Conackamack is one of the islands
  that Darwin is observing. What are some selected
  traits that would benefit a student and help them
  to survive and make it to the high school and
  beyond? In other words, what species of student
  would be strong enough to survive our
  educational system?