23.1 The Loss of Biodiversity

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23.1 The Loss of Biodiversity

• 1. Discuss extinction and how it occurs.
• 2. Explain habitat destruction and the loss of
  biodiversity, and how they are related.
• 3. Relate the concepts of extinction,
  biodiversity, and habitat destruction

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The Loss of Biodiversity

• Do the names Stegosaurus, Triceratops, and
  Tyrannosaurus rex sound familiar? These
  dinosaurs and many others roamed Earth millions
  of years ago. All that remains of the dinosaurs
  are fossils.
• Today, the lowland gorillas, several species
  of whale, and countless plants and other
  organisms are threatened with extinction. Human
  activity is destroying many of Earths habitats.
  As habitats disappear, the organisms adapted to
  those habitats also disappear.

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The Loss of Biodiversity

• Every organism is adapted to live in a certain
  habitat. If a habitat is altered or destroyed,
  the organisms adapted to that habitat must either
  find a new habitat or die.
• If a species is generalized, it may be able to
  occupy another niche. Specialized species almost
  always die with their habitats.
• The disappearance of a species from all or part
  of the species geographical range is called
  extinction.

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The Loss of Biodiversity

• When the last population of a species dies, some
  diversity in the ecosystem is lost. Because the
  extinction of a species affects factors such as
  the flow of energy and matter and the habitats of
  other organisms, a loss in biodiversity can upset
  the balance, health, and stability of an
  ecosystem.

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Extinction

• Extinctions are a natural part of ecosystem
  function.
• More than 99 of the species that have lived on
  Earth are extinct today.
• All ecosystems change, and niches appear and
  disappear with these changes.
• Species that lack adaptations for survival in a
  changing ecosystem become extinct.
• Other species may evolve to fill new niches or
  empty niches lived by extinct species.

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Extinction

• Relatively short periods of time in which many
  species die are called mass extinction.
• Mass extinctions are typically followed by rapid
  evolution as the few organisms that survive
  evolve to fill vacant niches.
• Earth may currently be experiencing another mass
  extinction. The activities of one species
  humans are causing many other species to become
  extinct year after year.

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Extinction

• Many human activities contribute to the
  extinction of species. The most serious factor
  is deforestation and other types of habitat
  destruction
• 50 - Habitat destruction and commercial
  harvesting.
• 18 - Hunting and poaching
• 16 - Alien species introduction
• 16 - Pollution, others

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Loss of Habitat

• Extinctions and the resulting loss of
  biodiversity often occur when humans destroy the
  habitat of organisms. Disturbing the part of an
  ecosystem that an organism needs to survive is
  called habitat destruction. Cutting down all the
  trees in a forest is one form of habitat
  destruction.

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Loss of Habitat

• Land development is another form of habitat
  destruction. Draining swamps for housing
  complexes, and altering wetlands for use as
  resorts, marinas, and farmlands, destroy fragile
  wetland habitats.
• Changing the course of rivers by using dams to
  control water flow can destroy aquatic habitats.

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Loss of Habitat

• Native species can also be threatened by other
  species that are introduced by humans.
• Non-native species introduced to an area by
  humans are called alien species.
• For example, the water hyacinth is an ornamental
  plant that was brought to Louisiana from South
  America. In many ecosystems, the water hyacinth
  has out-competed other plants for the resources
  in the ecosystem.

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Loss of Habitat

• Human activity is destroying or altering habitats
  in al biomes.
• The rate of biodiversity loss increases every
  day.
• As the human population grows, Earth will
  continue to lose biodiversity as people alter m
  ore habitats. As the number of humans increases,
  the amount of space available to other organisms
  declines.

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The Endangered Species Act

• The main provisions of the Endangered Species Act
  are
• The United States Fish and Wildlife Service must
  keep a list of all threatened and endangered
  species.
• Threatened or endangered animals may not be
  caught or killed.
• Threatened or endangered plants may not be
  disturbed.
• Threatened or endangered species and products
  made from them may not be bought or sold.
• The federal government may not construct any
  project that jeopardizes endangered species.
• The Fish and Wildlife Service must prepare a
  species recover plan for each threatened or
  endangered species.
• http//www.fws.gov/endangered/

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The Endangered Species Act

• Think About
• Many ecologists thing the Endangered Species Act
  focuses too much on individual species. They
  feel the emphasis should be on whole habitats,
  not on individual species.

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The Loss of BiodiversityHomework

1. Modeling a Bald Eagle Population Activity (p
   392).
2. Part Two find 2 examples from the plant kingdom
   and 2 examples from the animal kingdom that are
   now extinct in the state of New Jersey.