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EXTINCTION PROCESSES. EXTINCTION PROCESSES. EXTINCTION PROCESSES. Rare species are at risk due to : environmental stochasticity. Environmental Stochasiticity Examples – variable rate of increase.

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extinction processes2
EXTINCTION PROCESSES
  • Rare species are at risk due to:
    • environmental stochasticity
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
extinction processes4
EXTINCTION PROCESSES
  • Rare species are at risk due to:
    • genetic stochasticity
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
conservation and human resource use1
CONSERVATION AND HUMAN RESOURCE USE

Richmond, VA – USDA photo

conservation and human resource use2
CONSERVATION AND HUMAN RESOURCE USE

Texas oil wells

Russian coal power plant

conclusion
CONCLUSION
  • Conservation will fail unless:
    • human population is controlled
    • human resource use is moderated
wildlife reintroductions
Wildlife Reintroductions
  • Does habitat remain?
wildlife reintroductions1
Wildlife Reintroductions
  • Viable Population?
    • PVA
      • VORTEX
      • RAMAS
wildlife reintroductions2
Wildlife Reintroductions
  • Viable Population?
    • PVA
      • VORTEX
      • RAMAS
      • Incorporate GIS
wildlife reintroductions3
Wildlife Reintroductions
  • Genetic Considerations –
genetic considerations why should you care
Genetic Considerations: Why Should You Care?
  • Genetic variation is the underlying basis for adaptation to future environmental change
  • Loss of genetic variation is often a direct consequence of species reintroduction
  • Understanding how genetic loss occurs can help to prevent management actions that decrease the genetic diversity of reintroduced wildlife species
wildlife reintroductions4
Wildlife Reintroductions
  • Genetic Considerations
    • Inbreeding
wildlife reintroductions5
Wildlife Reintroductions
  • Genetic Considerations
    • Founder Effect
founder effect
Founder Effect
  • The reduction in overall genetic diversity experienced as a consequence of population establishment from a limited sample of individuals
    • Most reintroductions and natural colonization events exhibit Founder Effects
    • The magnitude of the effect depends upon the number of animals translocated or colonizing an area
wildlife reintroductions6
Wildlife Reintroductions
  • Genetic Considerations
    • Genetic Bottleneck
bottleneck
Bottleneck
  • An event in which a population drops significantly in size and then recovers
  • Events such as habitat loss, over harvest, or reintroduction can create bottlenecks and the magnitude of the effect on genetic diversity depends upon:
    • Number of individuals at lowest point
    • Length of time population remains depressed
genetic drift
Genetic Drift
  • Random fluctuations in gene frequencies due to temporal variance in survival and reproduction
    • Small populations drift more rapidly than large ones
    • Higher reproductive and survival rates can slow the rate of genetic drift
    • Genetic drift can result in loss of genetic diversity as well as increases in the frequency of rare alleles
inbreeding
Inbreeding
  • Mating of closely related individuals
  • Anytime genes that are alike by descent (i.e., from a shared ancestor) come together within individuals
    • Enhanced by slow population growth rates
    • Affected by mating system
    • Influenced by the relatedness of the initial population founders (e.g. reintroductions)
slide39

Trap and Transplant

Reintroduced Population

slide41

10

10 Generation Bottleneck

Genetic Drift

Inbreeding

slide42

20 Generation Bottleneck

20

Genetic Drift

Loss of Allelic Diversity Apparent

Inbreeding

slide43

30

30 Generation Bottleneck

Genetic Drift

Inbreeding

wildlife reintroductions7
Wildlife Reintroductions
  • Genetic Considerations
    • Marten reintroductions