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.

• 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?• 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?

• 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.

Characteristic Examples

Low reproductive rate(K-strategist)

Specialized niche

Narrow distribution

Feeds at high trophic level

Fixed migratory patterns

Rare

Commercially valuable

Large territories

Blue whale, giant panda,rhinoceros

Blue whale, giant panda,Everglades kite

Many island species,elephant seal, desert pupfish

Bengal tiger, bald eagle,grizzly bear

Blue whale, whooping crane,sea turtles

Many island species,African violet, some orchids

Snow leopard, tiger, elephant, rhinoceros, rare plants and birds

California condor, grizzly bear, Florida panther

What puts them

at risk?

Fish

Percentage of

threatened/ endangered

Mammals

Reptiles

Plants

Birds

34% (51% of freshwater species)

24%

20%

14%

12%

Indian Tiger

Range 100 years ago

Range today(about 2,300 left)

Indian Tiger

Black Rhino

Range in 1700

Range today(about 2,400 left)

Black Rhino

African Elephant

Probable range 1600

Range today(300,000 left)

African Elephant

Figure 12-7dPage 232

Asian or Indian Elephant

Former range

Range today(34,000–54,000 left)

Asian Elephant

Maintenance through Conservation

Maintaining and protecting wildlife consists of 3 major approaches:

1.Species approach – protecting endangered species though legislation.

2.Ecosystem approach – persevering balanced ecosystems

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???

• 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• 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• 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 12-10Page 236

Kudzu spreading

Figure 12-9aPage 235

Purple looselife European starling African honeybee(“Killer bee”)

Nutria Salt cedar(Tamarisk)

Marine toad Water hyacinth Japanese beetle Hydrilla European wild boar(Feral pig)

Deliberately introduced Species

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

Sea lamprey(attached to lake trout)

Argentina fire ant Eurasian muffleBrown tree snake Common pigeon(Rock dove)

Formosan termite Zebra mussel Asian long-hornedbeetle

Asian tiger mosquito Gypsy moth larvae

Accidentally introduced Species

1918

2000

Argentina Fire Ant Distribution

Characteristics ofSuccessful

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

Characteristics ofEcosystems Vulnerable

to Invader Species

• 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

Will we be invaded?

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?

• 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)