8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species. - PowerPoint PPT Presentation

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8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species.

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8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species. Extinction is forever!! When is a species considered extinct? – PowerPoint PPT presentation

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Title: 8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species.


1
8-2.7 Summarize the factors, both natural and
man-made, that can contribute to the extinction
of a species.
2
Extinction is forever!!
  • When is a species considered extinct?
  • If no members of that species are still alive.
  • Most organisms that have ever lived on Earth are
    now extinct.

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Mass Extinction
  • Sudden extinctions (confined to a few million
    years or less) which sweep away a large variety
    of living creatures.
  • Geologic time is marked by these events.
  • Paleozoic era ended theoretically because of a
    major climate shift.
  • Mesozoic era ended theoretically because an
    object from space struck Earth.
  • Cenozoic era continues today..

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Factors that contribute to extinction
  • Natural factors
  • Have caused extinctions throughout history.
  • Man-made factors
  • Have caused extinction in more recent times.
  • Brainstorm potential examples of each type.

7
On a clean sheet of paper (to be kept with
notes). Set up the entire page as shown below.
Natural factors
Man-Made factors
8
Natural Factors
  • Organisms could not survive changes due to
    various natural events.
  • Natural extinctions have occurred throughout
    geologic history.
  • Not all extinctions have a negative impact.
  • They clear the way for new kinds of life.

9
Natural Factors of Extinction
  • Volcanic Activity
  • Huge lava flows that produced enormous amounts of
    ash.
  • The ash in the air altered the global climate and
    ocean chemistry.

10
Natural Factors of Extinction
  • Global Warming
  • Animals could not survive the extreme change in
    temperatures and climate.
  • Global Cooling (Ice Ages)
  • Cooling events caused Glaciation events
  • Ocean water would freeze and therefore lower the
    sea level.

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Natural Factors of Extinction
  • Oxygen Depletion
  • As water cools, it causes dramatic shifts in
    limiting factors such as oxygen.
  • As oxygen levels in sea water were depleted, many
    species died out.

13
Natural Factors of Extinction
  • Asteroid or comet impact
  • The impact from a huge asteroid would have sent
    tidal waves across the earth and caused many
    fires.
  • Clouds of dust and ash would block the sunlight.
  • The planet would cool and plants and animals
    would die due to lack of sunlight.
  • The impact that killed the Dinosaurs was thought
    to have occurred in somewhere near Mexico.

14
Chalk Talk
  • Review of natural factors of extinction.

15
Man-made Factors of Extinction
  • Many plants and animals are likely to become
    extinct in the near future.
  • Humans remove survival needs of many organisms.
  • We are also threatening our own biological
    resources.
  • Man-made factors are damaging the Earth.

16
Man-made Factors of Extinction
  • Cutting of rainforests
  • Destroys habitats and food sources of many
    different animals.
  • Trees are logged for human needs.

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Man-made Factors of Extinction
  • Removing of Natural Habitats
  • Cutting down rainforests, agricultural activities
    and houses for humans.
  • Animals have no where to live, breed and hunt.

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Man-made Factors of Extinction
  • Over-harvesting or Hunting
  • Many animals have been hunted to extinction by
    humans.
  • Example, the Carolina Parakeet.
  • Lived in the southeastern United States.
  • Appeared 5 million years ago and became extinct
    in the early 1920s from hunting.

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Man-made Factors of Extinction
  • Pollution
  • Industrial activities have polluted rivers and
    oceans with toxic chemicals.
  • Introduction of foreign species
  • Sailors would bring domesticated animals to
    remote areas. (dogs, rats)
  • These animals would kill native animals and
    compete for food sources.

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Chalk Talk
  • Review of man-made factors of extinction.

39
KEY QUESTIONS
1. What is extinction?
2. What are some man-made factors that
contribute to the extinction of plants and
animals?
3. What are some natural phenomena that
contributes to the extinction of plants and
animals?
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