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EXTINCTION PROCESSES

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 PROCESSES

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  1. EXTINCTION PROCESSES

  2. EXTINCTION PROCESSES

  3. EXTINCTION PROCESSES • Rare species are at risk due to: • environmental stochasticity

  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

  7. EXTINCTION PROCESSES • Rare species are at risk due to: • genetic stochasticity

  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

  21. CONSERVATION AND HUMAN RESOURCE USE www.usda.gov

  22. CONSERVATION AND HUMAN RESOURCE USE Richmond, VA – USDA photo

  23. CONSERVATION AND HUMAN RESOURCE USE Texas oil wells Russian coal power plant

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

  25. Reintroductions & Translocations

  26. Wildlife Reintroductions • Does habitat remain?

  27. Wildlife Reintroductions • Viable Population? • PVA • VORTEX • RAMAS

  28. Wildlife Reintroductions • Viable Population? • PVA • VORTEX • RAMAS • Incorporate GIS

  29. Wildlife Reintroductions • Genetic Considerations –

  30. 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

  31. Wildlife Reintroductions • Genetic Considerations • Inbreeding

  32. Wildlife Reintroductions • Genetic Considerations • Founder Effect

  33. 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

  34. Wildlife Reintroductions • Genetic Considerations • Genetic Bottleneck

  35. 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

  36. 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

  37. 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)

  38. Different Colors Represent Copies of Different Genes Hypothetical SourcePopulation

  39. Trap and Transplant Reintroduced Population

  40. Founder Effects

  41. 10 10 Generation Bottleneck Genetic Drift Inbreeding

  42. 20 Generation Bottleneck 20 Genetic Drift Loss of Allelic Diversity Apparent Inbreeding

  43. 30 30 Generation Bottleneck Genetic Drift Inbreeding

  44. Wildlife Reintroductions • Genetic Considerations • Marten reintroductions

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