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Value of wild species & biodiversity • Ecosystem capital: goods & services provided to humans by natural systems • ecosystem capital = ecosystems • ecosystems = wild species • Ecosystem sustainability = save ecosystem integrity, resilience, processes, biodiversity © 2011 Pearson Education, Inc. Biological wealth • 2 million species examined, named, classified • 5–30 million species • Biota: natural species of living things • Biological wealth: biota + their ecosystems • = ecosystem capital & sustains humans • major part of a country’s total wealth • Biodiversity: variety of living species © 2011 Pearson Education, Inc. Biodiversity Value • Why shouldn’t we hunt species to extinction? • Wild species have value & essential to preserve • By identifying this value we can assess our moral duties to species © 2011 Pearson Education, Inc. • Instrumental value: a species’ existence benefits some other organism • Food, shelter, source of income • Usually anthropocentric • preserve species = enjoy benefits provided • Intrinsic value: value for own sake • not have to be useful to us • Do animals have rights? Or are they simply property? • Many believe only humans have intrinsic value • no reason to preserve “insignificant” species © 2011 Pearson Education, Inc. Recreational, aesthetic, and scientific uses © 2011 Pearson Education, Inc. • Ecotourism: tourists visit a place to observe wild species or unique ecological sites • It is the largest foreign exchange-generating enterprise for many developing countries • Environmental degradation affects commercial interests © 2011 Pearson Education, Inc. Biodiversity & its decline • Biodiversity = genetic diversity too • Species # • How “even” the species are • ↓biodiversity if dominated by 1 species with few other species • ↑biodiversity if dominance of any 1 species ↓ © 2011 Pearson Education, Inc. • Endemic species- found in 1 habitat • at risk • North America still not well-known • At least 500 species (100 vertebrates) extinct • 1/3 species are vulnerable or extinct © 2011 Pearson Education, Inc. North America • Freshwater habitats ↑ risk • Ex: Mussels, crayfish, fishes, amphibians • American SE ↑ freshwater diversity • Declining • Fish, amphibians, songbirds • More than 25% of North American birds are declining © 2011 Pearson Education, Inc. The state of U.S. species © 2011 Pearson Education, Inc. Global outlook • The global loss of biodiversity is disturbing • The background (past) extinction rate is less than one extinction every thousand years for mammals • Except for the five great extinction events • Current extinction rate = 100–1,000 times greater than past rates • For mammals and birds = 20–25 species per 100 years • Rates for all groups = 850 species over 500 years • 23% of mammal species and 12% of bird species are threatened © 2011 Pearson Education, Inc. Species extinction rates © 2011 Pearson Education, Inc. Most threatened species are in the tropics • The tropics have almost unimaginable biodiversity • 43 species of ants occur on one tree in Peru • Equal to all ant fauna of the British Isles • 300 species of trees on a 1-ha (2.5-acre) plot • 1,000 species of beetles on one tree species in Panama • Tropical forests are also experiencing the highest rate of deforestation • The species inventory is so incomplete it’s almost impossible to assess extinction rates © 2011 Pearson Education, Inc. Reasons for the decline • HIPPO • • • • • Habitat destruction Invasive species Pollution Population Overexploitation © 2011 Pearson Education, Inc. Biodiversity loss in the developing world • developing world • Biodiversity is greatest • So is human population growth • Asia & Africa have lost two-thirds of their original natural habitat • People’s desire for a better life • Desperate poverty • Global market for timber and other resources © 2011 Pearson Education, Inc. The border of Haiti and the Dominican Republic © 2011 Pearson Education, Inc. Habitat change: fragmentation • mosaic of different land uses • contrast with neighboring patches • Fragmentation small # & species populations • Species vulnerable to extinction © 2011 Pearson Education, Inc. Fragmentation © 2011 Pearson Education, Inc. Fragmentation: edge • Reducing habitat size increases edge • Exposing species to predators and nest parasites • Edge is beneficial to some species but not to others • Kirtland’s warbler, an endangered species, depends on jack pines in Michigan • Forests have been fragmented, creating edge • Brown-headed cowbirds are nest parasites that lay their eggs in the warbler’s nest • Edge also favors nest predators (crows, magpies, jays) © 2011 Pearson Education, Inc. Habitat change: simplification and intrusion • Simplification: humans simplify habitats • Removing logs and trees changes forest microhabitats • Streams are channelized (straightened), reducing fish and invertebrate species • Intrusion: human structures • Millions of migrating birds crash into telecommunication towers • Cell phone tower lights affect birds migrating at night • Up to a billion birds die each year by crashing into windows © 2011 Pearson Education, Inc. Invasive species • An exotic (alien) species: one that is introduced into an area from somewhere else • Most don’t survive or don’t become pests • Invasive species: thrives, spreads, and can eliminate native species by predation or competition • Accidental introductions: the brown tree snake • • • • Entered Guam on cargo ships Within 50 years, it eliminated 9 of 12 bird species It has no natural enemies Wildlife officials are trying to prevent its spread © 2011 Pearson Education, Inc. The brown tree snake © 2011 Pearson Education, Inc. • Aquaculture: the farming of shellfish, seaweed, and fish • Introducing parasites, seaweeds, invertebrates, pathogens • Species escape and enter nearby waterways © 2011 Pearson Education, Inc. The Brazilian pepper bush © 2011 Pearson Education, Inc. Invasive species and trophic levels • Nonnative plants have different resistance mechanisms • Make it harder for herbivores to eat • Energy and materials may not pass up the food chain • Norway maples were introduced to North America in 1756 • They provide less food up the food chain for herbivores (caterpillars) and their predators (song birds) © 2011 Pearson Education, Inc. © 2011 Pearson Education, Inc. Population • Human populations put pressure on species • Direct use, habitat conversion, pollution • Large numbers of humans use resources wild species need • Even if each person uses small amounts of resources • A small group of people can overuse resources • People with highly consumptive resources have a disproportionate effect on the environment • Different levels of consumption and numbers of people drive tensions between countries © 2011 Pearson Education, Inc. Overexploitation: trade in exotics • Overexploitation: overharvest of a particular species • Removing individuals faster than they can reproduce • Overuse of species harms ecosystems • Driven by greed, ignorance, desperation, poor management • Overcutting forests, overgrazing, overhunting, etc. • Trade in exotics: much trade is illegal • Illegal trade generates $12 billion/yr, the third largest source after drugs and guns • Consumers pay huge prices for “luxuries” (e.g., polar bear rugs) © 2011 Pearson Education, Inc. Consequences of losing biodiversity • Biodiversity is essential for ecosystem goods and services • Mangroves and coral reefs buffer against storms • Ecotourism depends on biodiversity • Energy flow and nutrient cycling are driven by species • Keystone species: species whose role is vital to survival of other species • Predators control herbivores • Umbrella species: larger animals that need unspoiled habitat (wolves, elephants, tigers, moose, etc.) © 2011 Pearson Education, Inc. Highway overpasses © 2011 Pearson Education, Inc. Cougar on the roof © 2011 Pearson Education, Inc. Endangered Species Act (1973) • Endangered species: in imminent danger of becoming extinct if it is not protected • Includes genetically distinct subpopulations (subspecies) • Threatened species: in jeopardy but not yet endangered • An officially recognized endangered or threatened species • Fines are levied for killing, trapping, uprooting (plants), or engaging in commerce • Administered by the U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration Fisheries Service © 2011 Pearson Education, Inc. Endangered species © 2011 Pearson Education, Inc. Elements of the Endangered Species Act • Listing: by the appropriate agency, individuals, groups, state agencies • Based on the best available information • Does not include any economic impact of listing • Critical habitat: areas where a species is or could spread as it recovers • Includes privately held lands • Recovery plans: designed to allow listed species to survive and thrive • Developed by the appropriate agency © 2011 Pearson Education, Inc. The American bald eagle © 2011 Pearson Education, Inc. The Red List • Maintained by the IUCN for threatened species • Evaluates the risk of extinction for thousands of species • Frequently updated and available on the Internet • In 2008, it had 16,928 species • Each species is classified • Given its distribution, documentation, habitat, ecology, conservation measures, and data sources • Not actively engaged in preserving species • It is the basis of conservation activities • Provides crucial leadership © 2011 Pearson Education, Inc. Critical ecosystem partnership fund • Sponsored by multiple entities and foundations • Provides grants to NGOs and community-based groups for conservation activities in biodiversity “hot spots” • Hot spots are 34 regions making up 2.3% of Earth’s land surface • Contain 75% of the most threatened species • By 2008, the fund had provided $102 million • 1,300 partners to work on preserving biodiversity in these hot spots © 2011 Pearson Education, Inc. Biodiversity hot spots © 2011 Pearson Education, Inc.