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Chapter 12

Chapter 12. Sustaining Biodiversity: The Species Approach . Key Concepts. Human effects on biodiversity Importance of biodiversity How human activities affect wildlife Management of wildlife. 1% Probably extinct. 7% Critically imperiled. 8% Imperiled. 16% Vulnerable.

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Chapter 12

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  1. Chapter 12 Sustaining Biodiversity: The Species Approach

  2. Key Concepts • Human effects on biodiversity • Importance of biodiversity • How human activities affect wildlife • Management of wildlife

  3. 1% Probably extinct 7% Critically imperiled 8% Imperiled 16% Vulnerable 1% Other 67% Secure or apparently secure US Diversity

  4. What Increases Biodiversity? • Physically diverse habitat • Moderate environmental disturbance • Small variations in conditions • Middle stages of ecological succession

  5. What Decreases Biodiversity? • Environmental stress • Large environmental disturbance • Extreme environmental conditions • Severe limiting factors • Introduction of alien (exotic) species • Geographic isolation

  6. Arctic Circle Arctic Circle 60° EUROPE NORTH AMERICA ASIA 30°N Tropic of Cancer Atlantic Ocean AFRICA Pacific Ocean Pacific Ocean 0° 150° 120° 90° 30°W 0° 60°E 90° 150° SOUTH AMERICA Indian Ocean Tropic of Capricorn AUSTRALIA 30°S Antarctic Circle 60° ANTARCTICA Critical and endangered Threatened Stable or intact Projected Status of Biodiversity 1998–2018

  7. Strategies for Protecting Species

  8. Species Extinction • Local Extinction: when a species is no longer found in the area that it once inhabited (but is still found elsewhere in the world) • Ecological Extinction: so few members of a species are left that it can’t play its ecological role • Biological Extinction: species is not found anywhere on earth (permanent)

  9. Endangered and Threatened Species • Endangered Species: so few survivors that the species could soon become extinct • Threatened Species: still abundant in its natural range but is likely to become endangered due to declining numbers

  10. Extinction Risks • Low reproductive rate (K-strategists): blue whale, giant panda • Specialized niche: giant panda • Narrow distribution: island species • Feeds at high trophic level: Bengal tiger, bald eagle • Rare: island species, orchids • Commercially valuable: elephant

  11. How Do We Estimate Extinction Risks? • Population viability analysis (PVA): risk assessment to predict whether a population will persist for a certain # of generations • PVA is based on: resource needs, current and predicted habitat conditions, genetic variability, interactions with other species, reproductive rates

  12. Continued… • Minimum viable population (MVP): smallest number of individuals necessary for the survival of a population in a region • Minimum dynamic area (MDA): the minimum area of habitat needed to maintain the MVP

  13. Why Should We Care About Biodiversity? • Humans value nature in different ways • Instrumental value: usefulness to us • Intrinsic value: because they exist, regardless of use • Utilitarian (use): goods, services, recreation • Nonutilitarian (nonuse): aesthetic

  14. Value of Nature Instrumental Intrinsic (human centered) (species or ecosystem centered) Utilitarian Nonutilitarian Existence Goods Ecological services Aesthetic Information Recreation

  15. Causes of Depletion of Wild Species • Human population growth • Failure to value the environment • Increasing resource use • Poverty

  16. Habitat loss Habitat degradation Overfishing Basic Causes Introducing nonnative species Climate change • Population growth • Rising resource use • No environmental accounting • Poverty Commercial hunting Pollution Sale of exotic pets and decorative plants Predator and pest control

  17. Type of Nonnative Organism Annual Losses and Damages Crop disease $23.5 billion Crop weeds $23.4 billion Rats $19 billion Feral cats and outdoor pet cats $17 billion Crop insects $14 billion Livestock diseases $9 billion Forest insects and diseases $4.8 billion Zebra mussels $3 billion Common pigeon $1.1 billion Formosan termite $1.1 billion Damage from Nonnative Species Fishes $1.1 billion Asian clam $1.1 billion Feral pigs $0.8 billion Starlings $0.8 billion Fire ant $0.6 billion

  18. Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived • High dispersal rate • Release growth- inhibiting chemicals into soil • Generalists • High genetic variability • Similar climate to habitat of invader • Absence of predators on invading species • Early successional species • Low diversity of native species • Absence of fire • Disturbed by human activities

  19. What Can Be Done to Reduce Threat from Nonnative Species? • Identify characteristics that make species successful invaders and use this information to screen out invaders • Increase inspections of goods coming into a country • Pass laws to ban the transfer of harmful invader species

  20. Biome % of Area Disturbed Temperate broadleaf forests 94% Temperate evergreen forests 94% Temperate grasslands 72% Mixed mountain systems 71% Tropical dry forests 70% Subtropical and temperate rain forests 67% Cold deserts and semideserts 55% Mixed island systems 53% Warm deserts and semideserts 44% Habitat Disturbance by Biome Tropical humid forests 37% Tropical grasslands 26% Temperate boreal forests 18% Tundra 0.7%

  21. Hunting and Poaching

  22. Wild African Elephant • 1970: 2.5 million • Today: 300,000 • Killed for tusks (worth about $500-1500) • Bleed to death • 1989 ban on sale of ivory from elephants • Caused increased killing of walruses and hippos for ivory

  23. DO NOT POST TO INTERNET

  24. Protecting Wild Species I • Bioinformatics: managing, analyzing, and communicating biological information • Involves: 1. building computer databases 2. developing computer tools to analyze the information 3. communicating the information • Example: Species 2000- global research project with the goal of providing information about all species on earth

  25. Protecting Wild Species II • International Treaties • Convention on International Trade in Endangered Species (CITES) 1972 • Signed by 152 countries • Lists 900 species that cannot be commercially traded • Restricts international trade of 29,000 other at-risk species

  26. Protecting Wild Species III • National Laws • Lacey Act of 1900: prohibits transportation of live or dead animals (or their parts) across state borders without a permit • Endangered Species Act of 1973: illegal for Americans to import or trade any product made from an endangered or threatened species

  27. Protecting Wild Species IV • Habitat Conservation Plans • Compromise between endangered species and private landowners • Landowners are allowed to kill a certain # of endangered species on private land in exchange for taking steps to protect the species Possible steps: setting aside a preserve for the species, paying to relocate the species, paying for government buy habitat elsewhere

  28. Other Approaches to Protecting Wild Species • Wildlife refuges and protected areas • Gene banks (storing plant seeds), botanical gardens (cultivation of rare and endangered plants), and farms (raise for commercial sale) • Zoos and aquariums

  29. Wildlife Management • Laws regulating hunting and fishing • Harvest quotas • Population management plans • Improving habitat • Laws for migrating species

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