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13e Sustaining Biodiversity: The Species Approach Core Case Study: Polar Bears and Projected Climate Change • 20,000 – 25,000 polar bears in Arctic • Hunt seals on winter sea ice • Global warming is quickly reducing the amount of sea ice and how long it lasts in winter • Polar bears have less time to hunt and store fat for summer fasting • Projected 30-35% decline by 2050 • Potentially extinct from wild by 2100 Fig. 8-1, p. 152 8-1 What Role Do Humans Play in the Premature Extinction of Species? • Concept 8-1 Species are becoming extinct 100 to 1,000 times faster than they were before modern humans arrived on earth, and by the end of this century, the extinction rate is expected be 10,000 times higher than the background rate. Human Activities and Extinction • Background extinction rate • Current rate is 100-1000 times background extinction • Rate likely to rise to 10,000 times • Is a mass extinction coming? Current Extinction Rate Estimates Are Conservative • Species and biodiversity decrease in next 50–100 years • Biodiversity hotspot rates higher than global average • Degrading, simplifying, and destroying diverse environments Fig. 8-2, p. 154 Passenger pigeon Great auk Dodo Golden Toad Aepyornis (Madagascar) Fig. 8-2, p. 154 Science Focus: Estimating Extinction Rates (1) • Three difficulties 1. Not easy to document – takes a long time 2. Only 2 million species of 8-100 million identified 3. Little is known about the 2 million species Science Focus: Estimating Extinction Rates (2) • Study records of post-human extinctions with previous extinctions from the fossil record • DNA copying mistakes • How habitat reduction increases extinction • Mathematical models • Inadequate data and models • Normal: 1 million to 10 million years • Humans have greatly accelerated this Ecological Smoke Alarms • Endangered species • Threatened species • The first to go: large, slow, tasty, or have valuable parts • Some behaviors make species prone to extinction Fig. 8-3, p. 156 Grizzly bear Kirkland’s warbler Utah prairie dog Swallowtail butterfly Knowlton cactus Florida manatee African elephant Humpback chub Golden lion tamarin Siberian tiger Fig. 8-3, p. 156 Fig. 8-3, p. 156 Giant panda Black-footed ferret Mountain gorilla Florida panther Whooping crane Northern spotted owl California condor Hawksbill sea turtle Blue whale Black rhinoceros Fig. 8-3, p. 156 Fig. 8-4, p. 157 Characteristic Examples Low reproductive rate Blue whale, giant panda, rhinoceros Specialized niche Blue whale, giant panda, Everglades kite Narrow distribution Elephant seal, desert pupfish Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Fixed migratory patterns Blue whale, whooping crane, sea turtle Rare African violet, some orchids Commercially valuable Large territories Snow leopard, tiger, elephant, rhinoceros, rare plants and birds California condor, grizzly bear, Florida panther Fig. 8-4, p. 157 Characteristic Examples Low reproductive rate Blue whale, giant panda, rhinoceros Specialized niche Narrow distribution Blue whale, giant panda, Everglades kite Elephant seal, desert pupfish Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Fixed migratory patterns Rare Commercially valuable Large territories Blue whale, whooping crane, sea turtle African violet, some orchids Snow leopard, tiger, elephant, rhinoceros, rare plants and birds California condor, grizzly bear, Florida panther Stepped Art Fig. 8-4, p. 157 Fig. 8-5, p. 157 Fish 34% (51% of freshwater species) Amphibians 32% Mammals 25% 20% Reptiles Plants Birds 14% 12% Fig. 8-5, p. 157 Case Study: Extinction of the Passenger Pigeon • Audubon, 1813: 3 days for a flock to pass over • Extinct by 1900 – Good to eat – Feathers good for pillows – Bones good for fertilizer – Easy to kill 8-2 Why Should We Care about Preventing Species Extinction? • Concept 8-2 We should prevent the premature extinction of wild species because of the economic and ecological services they provide and because they have a right to exist regardless of their usefulness to us. Value of Species • Instrumental value of biodiversity – Food crops – Genetic information – Medicine – Bioprospectors – Ecotourism • Do not know what we lose when species go extinct Fig. 8-6, p. 158 Fig. 8-7, p. 158 Rauvolfia Rosy periwinkle Pacific yew Neem tree Foxglove Cinchona Rauvolfia sepentina, Southeast Asia Anxiety, high blood pressure Taxus brevifolia, Pacific Northwest Ovarian cancer Digitalis purpurea, Europe Digitalis for heart failure Cathranthus roseus, Madagascar Hodgkin's disease, lymphocytic leukemia Cinchona ledogeriana, South America Quinine for malaria treatment Azadirachta indica, India Treatment of many diseases, insecticide, spermicide Fig. 8-7, p. 158 Ethical Obligations • Intrinsic (existence) value • Stewardship viewpoint 8-3 How Do Humans Accelerate Species Extinction? • Concept 8-3 The greatest threats to any species are (in order) loss or degradation of its habitat, harmful invasive species, human population growth, pollution, climate change, and overexploitation. Fig. 8-8, p. 160 Natural Capital Degradation Causes of Depletion and Premature Extinction of Wild Species Underlying Causes • Population growth • Rising resource use • Undervaluing natural capital • Poverty Direct Causes • Habitat loss • Pollution • Commercial hunting and poaching • Habitat degradation and fragmentation • Climate change • Sale of exotic pets and decorative plants • Introduction of nonnative species • Overfishing • Predator and pest control Fig. 8-8, p. 160 Causes of Endangerment and Premature Extinction (HIPPCO) • • • • • • Habitat destruction Invasive species Population growth Pollution Climate change Overexploitation Habitat Loss • Deforestation of tropical areas greatest eliminator of species • Endemic species • Habitat fragmentation Fig. 8-9, p. 161 Fig. 8-9, p. 161 Indian Tiger Range 100 years ago Range today African Elephant Probable range 1600 Range today Black Rhino Range in 1700 Range today Asian or Indian Elephant Former range Range today Stepped Art Fig. 8-9, p. 161 Case Study: Declining Bird Species (1) • Decline of ~70% of ~10,000 known species • 12% threatened with extinction • Birds around humans benefited, but forest species declined • Long-distance migrants – greatest decline Case Study: Declining Bird Species (2) • Reasons – Habitat loss – Habitat fragmentation – Climate change • Birds are environmental indicators • Perform economic and ecological services Species Introductions • Most beneficial – food crops, livestock, pest control • 500,000 alien invader species globally • 50,000 nonnative species in the U.S. • Some definitely not beneficial Fig. 8-10, p. 163 Deliberately Introduced Species Purple loosestrife European starling African honeybee Nutria (“Killer bee”) Marine toad (Giant toad) Water hyacinth Japanese beetle Hydrilla Salt cedar (Tamarisk) European wild boar (Feral pig) Fig. 8-10, p. 163 Fig. 8-10, p. 163 Accidentally Introduced Species Sea lamprey Argentina fire (attached to lake ant trout) Brown tree snake Eurasian ruffe Common pigeon (Rock dove) Formosan termite Asian longhorned beetle Asian tiger mosquito Gypsy moth larvae Zebra mussel Fig. 8-10, p. 163 Deliberately introduced species Purple European loosestrife starling Marine toad (Giant toad) African honeybee Nutria (“Killer bee”) Water hyacinth Japanese beetle Hydrilla Salt cedar (Tamarisk) European wild boar (Feral pig) Accidentally introduced species Sea lamprey (attached to lake trout) Formosan termite Argentina fire ant Zebra mussel Brown tree snake Eurasian ruffe Common pigeon (Rock dove) Asian long- Asian tiger Gypsy moth horned beetle mosquito larvae Stepped Art Fig. 8-10, p. 163 Case Study: The Kudzu Vine • Kudzu introduced to control erosion • Prolific growth • Uses – Asians use powdered starch in beverages – Edible – Source of tree-free paper – Japanese kudzu farm in Alabama Fig. 8-11, p. 164 Disruptions from Accidentally Introduced Species • • • • • Downside of global trade Downside of traveling Argentina fire ant Burmese python Zebra mussel Fig. 8-12, p. 165 Prevention of Nonnative Species (1) • Identify characteristics of successful invaders • Detect and monitor invasions • Inspect imported goods • Identify harmful invasive species and ban transfer Prevention of Nonnative Species (2) • Ships discharge ballast waters at sea • Introduce natural control organisms of invaders Fig. 8-13, p. 165 Fig. 8-14, p. 166 Human Choices Drive Extinction • • • • Human population growth Excessive, wasteful consumption Use of pesticides Climate change DDT and Bioaccumulation • 1950s–1960s fish-eating bird populations drop • DDT biologically magnified in food webs • Bird’s eggshells thin and fragile • Leads to unsuccessful reproduction Fig. 8-15, p. 166 DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, or 3 ppt Fig. 8-15, p. 166 DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, or 3 ppt Stepped Art Fig. 8-15, p. 166 Case Study: Where Have All the Honeybees Gone? • Honeybees responsible for 80% of pollination of insect-pollinated plants • Population down 30% since the 1980s – Pesticides – Parasitic mites – Invasive African honeybees • 2008: 36% of honeybee colonies lost – Colony collapse disorder – New nicotine-based pesticides to blame? Illegal Killing and Trading of Wildlife • Poaching endangers many larger animals, rare plants • Over two-thirds die in transit • Illegal trade: $1.1 million per hour • Wild species depleted by pet trade • Exotic plants often illegally gathered Fig. 8-16, p. 168 Fig. 8-A, p. 168 The Value of Wild Rare Species • Declining populations increase black market values • Rare species valuable in the wild – eco-tourism • Some ex-poachers turn to ecotourism Rising Demand for Bush Meat • Demand increasing with population growth • Increased road access • Loggers, miners, ranchers add to pressure • Local and biological extinctions • Spread of HIV and Ebola virus Fig. 8-17, p. 169 8-4 How Can We Protect Wild Species from Premature Extinction? • Concept 8-4 We can reduce species extinction and help to protect overall biodiversity by establishing and enforcing national environmental laws and international treaties, creating a variety of protected wildlife sanctuaries, and taking precautionary measures to prevent such harm. International Treaties • Convention on International Trade of Endangered Species (CITES) • Convention on Biological Diversity (CBD) U.S. Endangered Species Act (1) • National Marine Fisheries Services – ocean species • U.S. Fish and Wildlife Service – other species • Listings based on biological factors • Forbids federal agency projects that jeopardize listed species or habitats U.S. Endangered Species Act (2) • • • • Fines violations on private land Illegal to sell or buy listed species 1,318 species listed USFWS and NMFS supposed to prepare recovery plan – 86% species in 2009 U.S. Endangered Species Act (3) • Successful recovery plans include American alligator, grey wolf, and bald eagle • Lax enforcement of imports and exports • Amended to give private landowners economic incentive to save species Science Focus: Accomplishments of the Endangered Species Act • Biologists defend limited success – Species listed only when gravely threatened – Takes long time for species to recover – >50% endangered species improving • Need more funding • Develop recovery plans more quickly • Core habitat established when listed Protection of Marine Species • ESA and international treaties protect endangered marine reptiles and mammals • Challenges to protecting marine species – Limited knowledge of species – Difficulty in monitoring and enforcing treaties – open oceans Sea Turtles Threatened • • • • • Six species critically endangered Loss or degradation of habitat Illegal harvest of eggs Threats from fishing methods Protection measures have helped Fig. 8-18, p. 171 Case Study: Protecting Whales (1) • Easy to kill • International Whaling Commission – Sets quotas – Often ignored – No enforcement powers • 1986: Whaling ban, although violated, greatly decreased whale kills Case Study: Protecting Whales (2) • Key countries that violate whaling ban – Japan – Norway – Iceland Fig. 8-19, p. 172 Establish Wildlife Refuges • • • • National Wildlife Refuge System Wetland refuges: ~75% 40 million American visitors 20% of listed species in refuge system • Many refuges in disrepair, and many allow mining, oil drilling, and off-road vehicles Storing Genetic Information • Gene or seed banks • Botanical gardens and arboreta • Farms – commercial sale of endangered species removes pressure Zoos and Aquariums for Protection • Collect species with long-term goal of returning them into habitat • Egg pulling • Captive breeding • 100–500 captive individuals to avoid extinction • 10,000 individuals to maintain capacity for biological evolution Case Study: Trying to Save the California Condor • • • • Last 22 individuals captured Released a few at a time 2009: 167 condors in the wild Threatened by lead poisoning from animal carcasses and gut piles The Precautionary Principle • When substantial preliminary evidence indicates an activity could harm humans or the environment, we should take precautionary measures to prevent or reduce the harm • Do even if cause-and-effect relationships are not yet clearly established • “Better safe than sorry”