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Chapter 9: Sustaining Biodiversity: The Species Approach

What Role Do Humans Play in the Premature Extinction of Species?

Extinctions Are Natural but Sometimes They Increase Sharply

  • Biological Extinction: No species member alive
  • Background Extinction: Natural low rate of extinction
  • Extinction Rate: Percentage or number of species that go extinct in a certain time period
  • Mass Extinction: 50-95% of species become extinct usually due to a major global change in environmental conditions.

Endangered and Threatened Species Are Ecological Smoke Alarms

  • Endangered Species: Species with few members that the species could become extinct
  • Threatened Species (vulnerable species): Still enough members to survive, but numbers declining -- may soon be endangered

Characteristics of Species That Are Prone to Ecological and Biological Extinction

  • Low reproductive rate
  • Specialized niche
  • Narrow distribution
  • Feeds at high trophic level
  • Fixed migratory patterns
  • Rare
  • Commercially valuable
  • Large territories

Why Should We Care About The Rising Rate of Species Extinction?

4 Reasons to Prevent Extinction

  1. Species provide natural resources and natural services

    1. Insects for pollution
    2. Birds for pest control

  2. Most species contribute economic services

    1. Plants for food, fuel, lumber, medicine

  3. It will take 5-10 million years to regain species’ biodiversity

  4. Many people believe species have an intrinsic right to exist

How Do Humans Accelerate Species Extinction?

HIPPCO

  • H: Habitat destruction, degradation, and fragmentation
  • I: Invasive (nonnative) species
  • P: Population and resource use growth
  • P: Pollution
  • C: Climate change
  • O: Overexploitation

Habitat Fragmentation

  • Habitat Fragmentation: Large intact habitat divided by roads, crops, urban development
    • Leaves habitat islands
    • Blocks migration routes
    • Divides populations
    • Inhibits migrations and colonization
    • Inhibits finding food

Causes of Depletion and Extinction of Species

  • Underlying Causes
    • Population growth
    • Rising resource use
    • Poverty
  • Direct Causes
    • Habitat loss
    • Invasive species
    • Pollution
    • Climate change
    • Overfishing
  • Bioaccumulation: Increase in concentration of a pollutant in an organism
  • Biomagnification: Increase in concentration of a pollutant in a food chain
  • Pesticides
    • Ex: DDT Banned in the U.S. in 1972

Characteristics of Successful Invader Species

  • High reproductive rates
  • Pioneer species
  • Long-lived
  • High dispersal rate
  • Generalists
  • High genetic variability

Characteristics of Ecosystems Vulnerable to Invader Species

  • Climate similar to the habitat of the invader
  • Absence of predators on invading species
  • Early successional systems
  • Low diversity of native species
  • Absence of fire
  • Disturbed by human activities

Controlling Invasive Species

  • Do not capture or buy wild animals/plants
  • Do not remove plants from their habitat
  • Do not release pets into the nature
  • Do not dump contents from an aquarium into the nature

Individuals Matter

  • Jane Goodall: Primatologist and anthropologist
  • 45 years of understanding and protecting chimpanzees
    • Chimps have tool-making skills

How Can We Protect Wild Species from Premature Extinction

Treaties and Acts that Help Protect Species

  • Convention on International Trade in Endangered Species (CITES): Singed by 172 countries in 1975
  • Convention on Biological Diversity: It focused on ecosystems and was ratified by 190 countries. (Not in the US)
  • Endangered Species Act: Identify and protect endangered species in the US and abroad. It also does not allow federal agencies from funding projects that threaten species that are already endangered
    • National Marine Fisheries Service: Protect and Identify ocean species
    • U.S. Fish and Wildlife Services: Protect and identify all other species

Gene Banks, Botanical Gardens, and Wildlife Farms Can Help Protect Species

  • Gene or seed banks: Preserve genetic material of endangered plants
  • Botanical gardens and arboreta are also known as living plants
  • Farms to raise organisms for commercial sale

Protecting Species

  • Do not buy items that endanger animal species
  • Do not buy products that are created by cutting old-growth forests
  • Do not buy animals that were taken from the wild
  • Do not buy plants that were taken from the wild

The Precautionary Principle

  • Precautionary Principle: Act to prevent or reduce harm when preliminary evidence indicates its needed
  • Species are primary components of biodiversity
  • Prevention of species
  • Prevention of ecosystems