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EXTINCTION PROCESSES. Rare species are at risk. EXTINCTION PROCESSES. Rare species are at risk. EXTINCTION PROCESSES. Rare species are at risk due to : environmental stochasticity Random variation in habitat quality

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extinction processes
EXTINCTION PROCESSES
  • Rare species are at risk
extinction processes1
EXTINCTION PROCESSES
  • Rare species are at risk
extinction processes2
EXTINCTION PROCESSES
  • Rare species are at risk due to:
    • environmental stochasticity
      • Random variation in habitat quality
      • Extreme cases = catastrophes
environmental stochasiticity examples variable rate of increase
Environmental Stochasiticity Examples – variable rate of increase

Muskox population on Nunivak Island, 1947-1964 (Akcakaya et al. 1999)

environmental stochasiticity example of random k
Environmental Stochasiticity- Example of random K
  • Serengeti wildebeest data set – recovering from Rinderpest outbreak
    • Fluctuations around K possibly related to rainfall
extinction processes3
EXTINCTION PROCESSES
  • Rare species are at risk due to:
    • demographic stochasticity
      • Random variation birth/death rates
        • “good” years and “bad” years
extinction processes4
EXTINCTION PROCESSES
  • Rare species are at risk due to:
    • genetic stochasticity
      • Random variation in gene freq. due to:
        • Genetic drift
        • Bottlenecks
        • inbreeding
extinction processes5
EXTINCTION PROCESSES

A. Specialization

  • habitat restriction
    • proboscis monkeys and mangrove swamps
extinction processes6
EXTINCTION PROCESSES

A. Specialization

  • habitat restriction
  • range restriction
    • golden-lion tamarins
extinction processes7
EXTINCTION PROCESSES

A. Specialization

  • habitat restriction
  • range restriction
  • body size and home-range size
    • maned wolf

Photo by Pete Oxford

extinction processes8
EXTINCTION PROCESSES

A. Specialization

B. Catastrophes

  • earthquakes, asteroids
  • 5 mass extinctions
  • Cretaceous-Tertiary extinctions
extinction processes9
EXTINCTION PROCESSES

A. Specialization

B. Catastrophes

  • the human catastrophe
  • humans have caused 75% of extinctions since 1600
humans and extinction
HUMANS AND EXTINCTION

A. Role of Overexploitation

  • Lessons from North America
humans and extinction1
HUMANS AND EXTINCTION

A. Role of Overexploitation

  • Bison
  • presettlement: ca. 60 million
  • used food, hides
  • weapon against Native Americans
  • by 1889: only 600
humans and extinction2
HUMANS AND EXTINCTION

A. Role of Overexploitation

B. Role of Exotics

  • introduced organisms
  • cause of 20% of extinctions since 1600
humans and extinction3
HUMANS AND EXTINCTION

B. Role of Exotics

  • Feral Pigs
    • game species
    • destroy understory and groundcover
    • effect on brown honeycreeper
    • expensive to exterminate

Po’ouli, n = 3 on 2/03

humans and extinction4
HUMANS AND EXTINCTION

B. Role of Exotics

  • Domestic Cats
    • domesticated to kill pests
    • in 1/3 of U.S. households
    • humans support high densities
humans and extinction5
HUMANS AND EXTINCTION
  • Cats: Effects on Native Wildlife
    • Wisconsin: 19 million songbirds, 140,000 game birds per year
    • Great Britain: 50 million small mammals per year
    • Australia: endangerment of eastern barred bandicoot

Photo: Ian McCann

humans and extinction6
HUMANS AND EXTINCTION

C. Role of Human Population Size

  • most abundant mammal (Suzuki)
  • currently about 6.7 billion
  • stabilize at ~9 billion by 2042
humans and extinction7
HUMANS AND EXTINCTION

C. Role of Human Population Size

  • Habitat Destruction
  • Habitat Disturbance
  • The “human footprint” on habitats is today’s biggest threat to mammals
    • Human density
    • Land transformation
    • Access to areas
    • Electrical power infrastructure
conservation and human resource use
CONSERVATION AND HUMAN RESOURCE USE
  • Humans use ca. 40% of total terrestrial NPP

www.usda.gov

conservation and human resource use1
CONSERVATION AND HUMAN RESOURCE USE
  • Humans use ca. 40% of total terrestrial productivity
  • Land pre-empted for agriculture and cities: extinction of 5% of land mammals

Richmond, VA – USDA photo

conservation and human resource use2
CONSERVATION AND HUMAN RESOURCE USE
  • Humans use 20-30% of total terrestrial productivity
  • Agriculture pre-emption: extinction of 5%
  • Energy pre-emption: extinction of 10% more of land mammals

Texas oil wells

Russian coal power plant

conclusion
CONCLUSION
  • Conservation will fail unless:
    • human population is controlled
    • human resource use is moderated