chapter 12 sustaining biodiversity species extinction
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Chapter 12: Sustaining biodiversity (species/extinction)

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Chapter 12: Sustaining biodiversity (species/extinction). Land and Water Use Unit. Types of Extinction. Local extinction : better known as extirpation. A species is no longer found in an area it used to inhabit, but can be found elsewhere.

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types of extinction
Types of Extinction
  • Local extinction: better known as extirpation. A species is no longer found in an area it used to inhabit, but can be found elsewhere.
  • Ecological extinction: too few members of that species exist in an area to continue to play their role in the ecology of an area (predator, prey, etc.)
  • Biological extinction: true extinction. No members of that species exist on Earth. Example: dinosaurs, passenger pigeon
remember these
Remember these?
  • Background extinction: “Normal” extinction that occurs at a low rate: 1-5 species per million. May be due to evolution…
  • Mass extinction: Extremely high rates of extinction. There have been 5 mass extinctions and we may be in a possible 6th mass extinction.
  • Reread 6th extinction from Ch. 1 internet activity for homework.
who re you calling threatened
Who’re you calling threatened?
  • Endangered species: Numbers are so low that the species could soon become extinct. Protected by law. (Endangered Species Act of 1973)
  • Threatened species: Numbers are low enough that species could soon become threatened. Protected by law.
  • Special concern: Animals that are suspected to be experiencing problems, but no documentation has been made. Not protected by law.
what puts them at risk
What puts them at risk?



Low reproductive rate


Blue whale, giant panda,


Specialized niche

Blue whale, giant panda,

Everglades kite

Narrow distribution

Many island species,

elephant seal, desert pupfish

Bengal tiger, bald eagle,

grizzly bear

Feeds at high trophic


Fixed migratory patterns

Blue whale, whooping crane,

sea turtles


Many island species,

African violet, some orchids

Commercially valuable

Snow leopard, tiger,

elephant, rhinoceros,

rare plants and birds

Large territories

California condor, grizzly

bear, Florida panther

34% (51% of freshwater species)






Percentage of threatened/ endangered





indian tiger
Indian Tiger

Range 100 years ago

Range today

(about 2,300 left)

Indian Tiger

black rhino
Black Rhino

Range in 1700

Range today

(about 2,400 left)

Black Rhino

african elephant
African Elephant

Probable range 1600

Range today

(300,000 left)

African Elephant

figure 12 7d page 232
Figure 12-7dPage 232

Asian Elephant

Former range

Range today

(34,000–54,000 left)

Asian or Indian Elephant

maintenance through conservation
Maintenance through Conservation

Maintaining and protecting wildlife consists of 3 major approaches:

  • Species approach – protecting endangered species though legislation.
  • Ecosystem approach – persevering balanced ecosystems
maintenance through conservation1
Maintenance through Conservation

3. Wildlife management approach – managing game species for sustained yield through interaction treaties to protect migration species, improving wild life habitats, regulating hunting and fishing, creating harvest quotas and developing population management plans.

why should we care
Why should we care???
  • Instrumental value
  • Gene pool/genetic information (useful for vaccines, resistance)
  • Wildlife tourism (existential value)
  • Recreational pleasure
  • Place in ecosystem (pollinator, keystone, indicator, etc)
  • “It’s like burning books before you read them.”
causes of endangerment
Causes of endangerment
  • Habitat destruction (for resources, farmland, residential, pollution)
  • Introduction of alien/non-native/invasive species
  • Overexploitation (over-harvested, over-hunted, poaching)
  • Disease
  • Pollution
  • Interrupted migration
oops i did it again
Oops – I did it again
  • Introduced on purpose:
    • Kudzu vine (prevent erosion - 1930)
    • House sparrow (eat cankerworms -1950)
    • Carp (“world’s finest fish” - 1877)
    • Nutria (fur)
    • Ring-neck pheasant (hunting -1881)
figure 12 9a page 235
Figure 12-9aPage 235

Purple looselife

European starling

African honeybee

(“Killer bee”)


Salt cedar


Marine toad

Water hyacinth

Japanese beetle


European wild boar

(Feral pig)

Deliberately introduced Species

unintentional introduction
Unintentional introduction
  • On ships, boats
  • On people
  • On shipping crates
  • On tire treads
  • Examples:
    • Fire ants
    • Zebra mussel
    • Water millfoil
figure 12 9b page 235
Figure 12-9b Page 235

Sea lamprey

(attached to lake trout)

Argentina fire ant

Brown tree snake

Eurasian muffle

Common pigeon

(Rock dove)

Formosan termite

Zebra mussel

Asian long-horned


Asian tiger mosquito

Gypsy moth larvae

Accidentally introduced Species

will we be invaded
Will we be invaded?

Characteristics of


Invader Species

Characteristics of

Ecosystems Vulnerable

to Invader Species

  • High reproductive rate, short generation time (r-selected species)
  • Pioneer species
  • Long lived
  • High dispersal rate
  • Release growth- inhibiting chemicals into soil
  • Generalists
  • High genetic variability
  • Similar climate to habitat of invader
  • Absence of predators on invading species
  • Early successional systems
  • Low diversity of native species
  • Absence of fire
  • Disturbed by human activities
it s the law
It’s the law…
  • CITES: Convention on International Trade in Endangered Species: 1975, treaty signed by 160 countries, lists 900 species that cannot be traded either alive or as products.
  • CBD: Convention on Biological Diversity. Signed by 186 countries legally binds governments of signing countries to attempt to reverse the loss of biological diversity. Each country forms a national conservation plan.
  • Lacey Act of 1900: US act, can’t transport live or dead wild animals or parts of them across state borders without permits
  • Endangered Species Act: 1973. Amended in 1982, 85, 88. Identifies animals as threatened or endangered and protects them by law.
zoos or not
Zoos or Not?
  • Read pages 245-247
  • Utilize the internet for additional support for your essay.
  • Essay – should be 3-4 paragraphs on whether or not zoos/aquariums/captivity programs should be utilized for endangered/threatened species (with no intention of releasing to the wild)