Presentation on theme: "Chapter 9. Passenger pigeon hunted to extinction by 1900 Commercial hunters used a "stool pigeon” Geological record shows five mass extinctions."— Presentation transcript:
Passenger pigeon hunted to extinction by 1900 Commercial hunters used a "stool pigeon” Geological record shows five mass extinctions Human activities: hastening more extinctions?
Concept 9-1A We are degrading and destroying biodiversity in many parts of the world, and these threats are increasing. Concept 9-1B Species are becoming extinct 100 to 1,000 times faster than they were before modern humans arrived on the earth (the background rate), and by the end of this century, the extinction rate is expected to be 10,000 times the background rate.
Human activity has disturbed at least half of the earth’s land surface Fills in wetlands Converts grasslands and forests to crop fields and urban areas Degraded aquatic biodiversity
Background extinction Extinction rate Mass extinction: causes? Poorly understood, but involve global changes in environmental conditions. Levels of species extinction Local extinction, or extirpation Ecological extinction Biological extinction
Premature extinctions due to Habitat destruction Overhunting, or overexploitation
Conservative estimates of extinction = % Growth of human population will increase this loss to times (to 1%) Rates are higher where there are more endangered species Tropical forests and coral reefs, wetlands and estuaries—sites of new species—being destroyed Speciation crisis
Endangered species International Union for the for the Conservation of Nature (IUCN), or the World Conservation Union. Since 1960, published Red List In 2007, listed 16, 306 animals and plants that are in danger of extinction—60% higher than in Threatened species, vulnerable species Characteristics of such species
Grizzly bear Kirkland’s warbler Knowlton cactus Florida manatee Africanelephant Utah prairie dog Swallowtailbutterfly Humpback chub Golden lion tamarin Siberian tiger Giant panda Black-footedferret Whooping crane Northern spotted owl Blue whale Mountain gorilla Florida panther California condor Hawksbill sea turtle Black rhinoceros Figure 9.4 Endangered natural capital. S ome species that are endangered or threatened with premature extinction largely because of human activities. Almost 30,000 of the world’s species and roughly 1,300 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger.
Fixed migratory patterns Blue whale, whooping crane, sea turtle Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Narrow distribution Elephant seal, desert pupfish Commercially valuable Snow leopard, tiger, elephant, rhinoceros, rare plants and birds Low reproductive rate (K-strategist) Blue whale, giant panda, rhinoceros CharacteristicExamples Rare African violet, some orchids Large territories California condor, grizzly bear, Florida panther Specialized niche Blue whale, giant panda, Everglades kite Figure 9.5 Characteristics of species that are prone to ecological and biological extinction. Question: Which of these characteristics helped lead to the premature extinction of the passenger pigeon within a single human lifetime?
Three problems Hard to document due to length of time Only 1.8 million species identified Little known about nature and ecological roles of species identified Document little changes in DNA Suggests species survive for 1 to 10 million years before going extinct. Use species–area relationship On average, 90% loss of habitat results in a 50% loss of species living in that habitat. Mathematical models
Concept 9-2 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. “It will take 5-10 million years for natural speciation to rebuild the biodiversity we are likely to destroy during your lifetime.”
Instrumental value – usefulness to us in providing ecological and economic services. Use value Ecotourism: wildlife tourism Genetic information Loss in diversity of crop species is cause for concern. Food crops, recreation, scientific information, lumber, paper, etc. Nonuse value Existence value Aesthetic value Bequest value Ecological value Energy flow, nutrient cycling, and population control—the scientific principles of sustainability that sustain and support life on earth.
1989 international treaty against poaching elephants Poaching on the rise Track area of poaching through DNA analysis of elephants Elephants damaging areas of South Africa: Should they be culled?
Intrinsic value, or existence value Species have an inherent right to exist and play their ecological roles, regardless of their usefulness to us. Edward O. Wilson: biophilia phenomenon Biophobia
Vulnerable to extinction Slow to reproduce Human destruction of habitats Important ecological roles Feed on crop-damaging nocturnal insects Pollen-eaters Fruit-eaters Unwarranted fears of bats
Concept 9-3 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.
Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation
NATURAL CAPITAL DEGRADATION Underlying Causes Population growth Population growth Rising resource use Rising resource use Undervaluing natural capital Undervaluing natural capital Poverty Poverty Direct Causes Habitat loss Habitat loss Pollution Pollution Commercial hunting and poaching Commercial hunting and poaching Habitat degradation and fragmentation Habitat degradation and fragmentation Climate change Climate change Sale of exotic pets and decorative plants Sale of exotic pets and decorative plants Introduction of nonnative species Introduction of nonnative species Overfishing Overfishing Predator and pest control Predator and pest control Causes of Depletion and Premature Extinction of Wild Species Figure 9.10 Underlying and direct causes of depletion and premature extinction of wild species (Concept 9-3). The major direct causes of wildlife depletion and premature extinction are habitat loss, degradation, and fragmentation. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems.
Figure 9.11 Natural capital degradation: reductions in the ranges of four wildlife species, mostly as the result of habitat loss and hunting. What will happen to these and millions of other species when the world’s human population doubles and per capita resource consumption rises sharply in the next few decades? Question: Would you support expanding these ranges even though this would reduce the land available for people to grow food and live on? Explain. (Data from International Union for the Conservation of Nature and World Wildlife Fund)
Globally, habitat loss, greatest in temperate biomes, pace picking up in tropics. Endemic species Hawaii, the extinction capital of America—63% of species at risk. Habitat islands Habitat fragmentation The Bali Mynah is distributed and endemic to the island of Bali, where it is the island's only surviving endemic species. This rare bird was discovered in 1910 and is one of the world's most critically endangered birds. In fact, it has been hovering immediately above extinction in the wild for several years.
Tropical Biologist Bill Laurance, et al. How large must a forest fragment be in order to prevent the loss of rare trees?
70% of the worlds 10,000 birds are declining; 12% are threatened with extinction. Habitat loss and fragmentation of the birds’ breeding habitats Forests cleared for farms, lumber plantations, roads, and development Intentional or accidental introduction of nonnative species Eat the birds
NumbersLocationReason(s) 75% of birds speciesSumatra’s lowland forestsLumber and palm plantations, used for biofuels 115 bird speciesBrazilBurning/clearing of rainforests for farms and ranches; 93% loss of Atlantic coastal rainforest; clearing of savannah-like cerrado for soybean plantations 30% of bird species, 70% of grassland species North AmericaHabitat loss and fragmentation of breeding habitat; replaced by roads and other developments. 28% of speciesWorldwideIntroduction of non-native bird-eating species 52 of 388 parrot speciesWorldwidePet trade 23 SeabirdsWorldwideBycatch from commercial fishing; pollution 40% of waterbirdsWorldwideLoss of wetlands
Seabirds caught and drown in fishing equipment Migrating birds fly into power lines, communication towers, and skyscrapers Other threats Oil spills Pesticides Herbicides Ingestion of toxic lead shotgun pellets
Greatest new threat: Climate change Environmental indicators Live in every climate and biome Respond quickly to environmental changes Easy to track Economic and ecological services
Cerulean warbler Sprague’s pipit Bichnell’s thrush Black-capped vireo Golden-cheeked warbler Florida scrub jay California gnatcatcher Kirtland'swarbler Henslow's sparrow Bachman's warbler Figure 9.13 The 10 most threatened species of U.S. songbirds. Most of these species are vulnerable because of habitat loss and fragmentation from human activities. An estimated 12% of the world’s known bird species may face premature extinction due mostly to human activities during this century. (Data from National Audubon Society)
Vultures poisoned from diclofenac in cow carcasses More wild dogs eating the cow carcasses More rabies spreading to people
Most species introductions are beneficial. Food Shelter Medicine Aesthetic enjoyment Nonnative species may have no natural enemies. Predators Competitors Parasites Pathogens
Figure 9.14 Some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States.
Imported from Japan in the 1930s to control soil erosion. “ The vine that ate the South” Could there be benefits of kudzu?
Argentina fire ant: 1930s Pesticide spraying in 1950s and 1960s worsened conditions Wiped out competitor ant species and made them more pesticide resistant. Burmese python
Prevent them from becoming established Learn the characteristics of the successful invader species and the types of ecosystems that are vulnerable to invasion. Inspection of imports. Ballast water from cargo ships. Set up research programs to try to find natural ways to control them: predators, parasites, bacteria and viruses. Ground surveys and satellite observations to detect and monitor invasions to develop better models for predicting spread.
Pesticides DDT: Banned in the U.S. in 1972 Bioaccumulation Biomagnification
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 ppm, or 3 ppt
Honeybees responsible for 80% of insect-pollinated plants Dying due to? Pesticides Parasites Bee colony collapse syndrome
Environmental impact on polar bears Less summer sea ice PCBs and DDT Can adversely affect their development, behavior, and reproduction. IUCN 2006 Study: Population projected to decline by %, and may be found only in zoos by end of century listed as threatened species 2008 listed as threatened species under US ESA.
Poaching and smuggling of animals and plants Animal parts Pets Plants for landscaping and enjoyment When commercially valuable species become endangered, black market prices soar. Prevention: research and education
Primatologist and anthropologist 45 years understanding and protecting chimpanzees Chimps have tool-making skills
Indigenous people sustained by bush meat More hunters leading to local extinction of some wild animals US Agency for International Development, trying to introduce alternatives in some areas. Fish farms Breeding large rodents, like cane rats.
Concept 9-4A We can use existing environmental laws and treaties and work to enact new laws designed to prevent species extinction and protect overall biodiversity. Concept 9-4B We can help to prevent species extinction by creating and maintaining wildlife refuges, gene banks, botanical gardens, zoos, and aquariums.
Concept 9-4C According to the precautionary principle, we should take measures to prevent or reduce harm to the environment and to human health, even if some of the cause-and-effect relationships have not been fully established, scientifically.
1975: Convention on International Trade in Endangered Species (CITES) Signed by 172 countries Convention on Biological Diversity (BCD) Focuses on ecosystems Ratified by 190 countries (not the U.S.)
Endangered Species Act (ESA): 1973 and later amended in 1982, 1983, and 1985 Identify and protect endangered species in the U.S. and abroad Hot Spots Habitat Conservation Plan (HCP) colony
Mixed reviews of the ESA Weaken it Repeal it Modify it Strengthen it Simplify it Streamline it
Species listed only when serious danger of extinction Takes decades for most species to become endangered or extinct More than half of the species listed are stable or improving Budget has been small
Suggested changes to ESA Increase the budget Develop recovery plans more quickly Establish a core of the endangered organism’s survival habitat
1903: Theodore Roosevelt Wildlife refuges Most are wetland sanctuaries More needed for endangered plants Could abandoned military lands be used for wildlife habitats?
Gene or seed banks Preserve genetic material of endangered plants Botanical gardens and arboreta Living plants Farms to raise organisms for commercial sale
Techniques for preserving endangered terrestrial species Egg pulling Captive breeding Artificial insemination Embryo transfer Use of incubators Cross-fostering
Limited space and funds Critics say these facilities are prisons for the organisms
Largest North American bird Nearly extinct Birds captured and breed in captivity By 2007, 135 released into the wild Threatened by lead poisoning
Species: primary components of biodiversity Preservation of species Preservation of ecosystems