CH 7 SEC 3

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CH 7 SEC 3

• EVOLUTION OF SPECIES

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GOAL/PURPOSE

• STUDENTS KNOW THE ROLE OF GENETIC VARIATION AND
  EXTINCTION HAS PLAYED IN THE FORMATION OF LIFE
  OVER THE HISTORY OF EARTH AND HOW WE ARE TODAY!

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VARIETY OF SPECIES

• HOW MANY MILLIONS OF SPECIES EXIST?
• 1.5 MILLION TO???
• KEY- OVER TIME, DIFFERENT ENVIRONMENTS AND
  GENETIC VARIATION HAVE PRODUCED, THROUGH NATURAL
  SELECTION, THE VARIETY OF ORGANISMS THAT EXIST
  TODAY.

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CONTD

• HABITAT- IS THE SPECIFIC ENVIRONMENT THAT
  PROVIDES THE THINGS AN ORGANISM NEEDS TO LIVE,
  GROW, AND REPRODUCE
• KEY-A NEW SPECIES CAN FORM WHEN A GROUP OF
  ORGANISMS REMAINS ISOLATED FROM THE REST OF ITS
  SPECIES LONG ENOUGH TO EVOLVE DIFFERENT TRAITS.

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CONTD

• GRAPHIC ISOLATION- IS WHEN SOME MEMBERS OF A
  SPECIES BECOME CUT OFF FROM THE REST OF THE
  SPECIES (SEE GALAPAGOS ISLANDS)
• http//video.nationalgeographic.com/video/places/p
  arks-and-nature-places/coasts-and-islands/ecuador_
  galapagos/

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INFERRING SPECIES RELATIONSHIPS

• KEY- SCIENTIST HAVE COMBINED THE EVIDENCE FROM
  DNA, PROTEIN STRUCTURE, FOSSILS, EARLY
  DEVELOPMENT AND BODY STRUCTURE TO DETERMINE THE
  EVOLUTIONARY RELATIONSHIPS AMONG SPECIES

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EXTINCTION OF A SPECIES

• EXTINCT- WHEN NO MEMBERS OF A SPECIES ARE ALIVE
  (WOOLLY MAMMOTHS)
• WHAT MAKES A SPECIES EXTINCT?
• KEY- EXTINCTION IS CAUSED BY A CHANGE IN A
  SPECIES ENVIRONMENT. THE MEMBERS OF THE SPECIES
  MAY NOT HAVE ADAPTATIONS THAT ALLOW THEM TO
  SURVIVE AND REPRODUCE IN THE CHANGED ENVIRONMENT

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EXTINCTION

• http//www.brainpop.com/science/ourfragileenvironm
  ent/extinction/preview.weml

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THERE ARE MANY WAYS EXTINCTION CAN HAPPEN

• A NEW DISEASE
• LOSS OF FOOD SOURCE
• PREDATORS KILL THEM OFF
• HUMAN IMPACT
• OVER HUNTING
• DESTRUCTION OF ENVIRONMENT
• CLIMATE CHANGE
• CATASTROPHIC EVENTS

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Contd

• Climate Change- has been the leading cause of
  extinction
• EX- an area that was once warm and moist becomes
  cool and dry
• Resulting- in plants dying and the animals that
  feed on those plants dying as well or becoming
  extinct
• KEY- SOME ORGANISMS IN A SPECIES MAY HAVE TRAITS
  THAT HELP THEM SURVIVE IN A CHANGED ENVIRONMENT.

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HORSESHOE CRABS HAVE SURVIVED MANY CLIMATE CHANGES
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HORSESHOE CRAB
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RECENTLY EXTINCT ANIMALS

• http//listverse.com/2009/07/25/10-recently-extinc
  t-animals/
• http//www.youtube.com/watch?v0Kwzg8WmSEU
• http//news.discovery.com/videos/why-tell-me-why-m
  ass-extinction.html

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REVIEW QUESTIONS

• WRITE THE QUESTION AND ANSWER
• 1. IDENTIFY 2 FACTORS THAT ACCOUNT FOR DIVERSITY
  OF SPECIES.
• 2. HOW CAN ISOLATION LEAD TO THE FORMATION OF A
  NEW SPECIES?
• 3. WHAT CAUSES EXTINCTION?