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EXTINCTION PROCESSES

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

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  1. EXTINCTION PROCESSES • Rare species are at risk

  2. EXTINCTION PROCESSES • Rare species are at risk

  3. EXTINCTION PROCESSES • Rare species are at risk due to: • environmental stochasticity • Random variation in habitat quality • Extreme cases = catastrophes

  4. Environmental Stochasiticity Examples – variable rate of increase Muskox population on Nunivak Island, 1947-1964 (Akcakaya et al. 1999)

  5. Environmental Stochasiticity- Example of random K • Serengeti wildebeest data set – recovering from Rinderpest outbreak • Fluctuations around K possibly related to rainfall

  6. EXTINCTION PROCESSES • Rare species are at risk due to: • demographic stochasticity • Random variation birth/death rates • “good” years and “bad” years

  7. EXTINCTION PROCESSES • Rare species are at risk due to: • genetic stochasticity • Random variation in gene freq. due to: • Genetic drift • Bottlenecks • inbreeding

  8. EXTINCTION PROCESSES A. Specialization • habitat restriction • proboscis monkeys and mangrove swamps

  9. EXTINCTION PROCESSES A. Specialization • habitat restriction • range restriction • golden-lion tamarins

  10. EXTINCTION PROCESSES A. Specialization • habitat restriction • range restriction • body size and home-range size • maned wolf Photo by Pete Oxford

  11. EXTINCTION PROCESSES A. Specialization B. Catastrophes • earthquakes, asteroids • 5 mass extinctions • Cretaceous-Tertiary extinctions

  12. EXTINCTION PROCESSES A. Specialization B. Catastrophes • the human catastrophe • humans have caused 75% of extinctions since 1600

  13. HUMANS AND EXTINCTION A. Role of Overexploitation • Lessons from North America

  14. HUMANS AND EXTINCTION A. Role of Overexploitation • Bison • presettlement: ca. 60 million • used food, hides • weapon against Native Americans • by 1889: only 600

  15. HUMANS AND EXTINCTION A. Role of Overexploitation B. Role of Exotics • introduced organisms • cause of 20% of extinctions since 1600

  16. 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

  17. HUMANS AND EXTINCTION B. Role of Exotics • Domestic Cats • domesticated to kill pests • in 1/3 of U.S. households • humans support high densities

  18. 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

  19. HUMANS AND EXTINCTION C. Role of Human Population Size • most abundant mammal (Suzuki) • currently about 6.7 billion • stabilize at ~9 billion by 2042

  20. 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

  21. CONSERVATION AND HUMAN RESOURCE USE • Humans use ca. 40% of total terrestrial NPP www.usda.gov

  22. 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

  23. 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

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

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