Chapter 12 Sustaining Biodiversity: The Species Approach SPECIES EXTINCTION • Species can become extinct: – ________: A species is no longer found in an.
Download ReportTranscript Chapter 12 Sustaining Biodiversity: The Species Approach SPECIES EXTINCTION • Species can become extinct: – ________: A species is no longer found in an.
Chapter 12 Sustaining Biodiversity: The Species Approach SPECIES EXTINCTION • Species can become extinct: – ________: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. – Ecologically: Occurs when so few members of a species are left they no longer play its _______role. – Globally (____________): Species is no longer found on the earth. Chapter Overview Questions • How do biologists estimate extinction rates, and how do human activities affect these rates? • Why should we care about biodiversity and species extinction? • Which human activities endanger wildlife? • How can we help prevent premature extinction of species? • What is reconciliation ecology, and how can it help prevent premature extinction of species? Core Case Study: The Passenger Pigeon - Gone Forever • Once the most numerous bird on earth. • In _______, Passenger Pigeon hunting became a big business. • By 1900 they became ______ from over-harvest and _______ _____. Figure 12-1 Global Extinction • Some animals have become prematurely extinct because of human activities. Figure 12-2 Passenger pigeon Great auk Dodo Dusky seaside sparrow Aepyornis (Madagascar) Fig. 12-2, p. 225 Endangered and Threatened Species: Ecological Smoke Alarms • Endangered species: so few ________ _____ that it could soon become ________. • ___________ _________: still abundant in its natural range but is likely to _______ ________ in the near future. Figure 12-3 Fig. 12-3, p. 226 Grizzly bear Utah prairie dog Kirkland’s warbler Knowlton cactus Florida manatee Swallowtail butterfly Golden lion tamarin Humpback chub African elephant Siberian tiger Fig. 12-3, p. 226 Giant panda Mountain gorilla Black-footed ferret Whooping crane Northern spotted Blue whale owl Florida panther California condor Hawksbill sea Black turtle rhinoceros Fig. 12-3, p. 227 SPECIES EXTINCTION • Some species have characteristics that make them vulnerable to ecological and biological extinction. • R-strategists: • K-strategists: Figure 12-4 Reproductive Patterns • r-selected species tend to be opportunists while Kselected species tend to be competitors. Figure 9-10 Characteristic Examples Low reproductive rate (K-strategist) Blue whale, giant panda, rhinoceros Specialized niche Blue whale, giant panda, Everglades kite Narrow distribution Feeds at high trophic level Fixed migratory patterns Rare Commercially valuable Large territories Many island species, elephant seal, desert pupfish Bengal tiger, bald eagle, grizzly bear Blue whale, whooping crane, sea turtles Many island species, African violet, some orchids Snow leopard, tiger, elephant, rhinoceros, rare plants and birds California condor, grizzly bear, Florida panther Fig. 12-4, p. 228 SPECIES EXTINCTION • Scientists use measurements and _______ to estimate ____________ rates. – The International Union for the ___________ of Nature and Natural Resources (IUCN) publishes an annual______ _____, listing the world’s threatened species. – The 2004 Red List contains __________ species at risk for extinction. SPECIES EXTINCTION • Percentage of various species types threatened with premature extinction from human activities. Figure 12-5 34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles Plants Birds 14% 12% Fig. 12-5, p. 228 SPECIES EXTINCTION • Scientists use models to estimate the risk of particular species becoming extinct or endangered. Number of species existing 5 million 14 million 50 million 100 million Effects of a 0.1% extinction rate 5,000 extinct per year 14,000 extinct per year 50,000 extinct per year 100,000 extinct per year Number of years until one million species are extinct IMPORTANCE OF WILD SPECIES • We should not cause the premature extinction of species because of the _________ and ________ services they provide. • Some believe that each wild species has an _________ right to exist. – Some people distinguish between the survival rights among various types of species (plants vs. animals). HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Conservation biologists summarize the most important causes of premature extinction as “_____”: – Habitat destruction, degradation, and ___________ – Invasive species – Population growth – Pollution – Overharvest HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • The greatest threat to a species is the loss, degradation, and fragmentation of where it lives. Figure 12-6 Habitat Overfishing loss Habitat degradation Climate change and fragmentation Introducing nonnative Predator and pest control species Pollution Commercial hunting and poaching Sale of exotic pets and decorative plants Secondary Causes • Population growth • Rising resource use • No environmental accounting • Poverty Basic Causes Fig. 12-6, p. 231 HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Reduction in ranges of four wildlife species, mostly due to habitat loss and overharvest. Figure 12-7 Indian Tiger Range 100 years ago Range today (about 2,300 left) Fig. 12-7a, p. 232 Black Rhino Range in 1700 Range today (about 3,600 left) Fig. 12-7b, p. 232 African Elephant Probable range 1600 Range today Fig. 12-7c, p. 232 Asian or Indian Elephant Former range Range today (34,000–54,000 left) Fig. 12-7d, p. 232 Case Study: A Disturbing Message from the Birds • Human activities are causing serious declines in the populations of many bird species. Figure 12-8 Cerulean warbler Florida scrub jay Sprague’s pipit Bichnell’s thrush California gnatcatcher Kirtland’s warbler Black-capped vireo Golden-cheeked warbler Henslow’s sparrowBachman’s warbler Fig. 12-8, p. 233 Case Study: A Disturbing Message from the Birds • The majority of the world’s bird species are found in South America. – Threatened with __________loss and _________species. Number of bird species 609 400 200 1 INVASIVE SPECIES Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats. • Many ________species provide us with food, medicine, and other benefits but a few can wipe out _______ ______, disrupt ________, and cause large economic losses. Figure 12-10 INVASIVE SPECIES • Many invasive species have been introduced intentionally. Figure 12-9 Deliberately Introduced Species Purple loosestrife European starling African honeybee (“Killer bee”) Marine toad (Giant toad) Water hyacinth Japanese beetle Nutria Hydrilla Salt cedar (Tamarisk) European wild boar (Feral pig) Fig. 12-9a, p. 235 INVASIVE SPECIES • Many invasive species have been introduced unintentionally. Figure 12-9 Accidentally Introduced Species Sea lamprey (attached to lake trout) Formosan termite Argentina fire ant Zebra mussel Brown tree snake Asian long-horned beetle Eurasian ruffe Common pigeon (Rock dove) Gypsy moth larvae Asian tiger mosquito Fig. 12-9b, p. 235 Fig. 12-9, p. 235 INVASIVE SPECIES • The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. – Most probably from ships. – No natural predators. INVASIVE SPECIES • _________is the best way to reduce threats from invasive species, because once they arrive it is almost ________ to slow their spread. Characteristics of Successful Invader Species • High reproductive rate, short generation time (r-selected species) • Pioneer species • Long lived Characteristics of Ecosystems Vulnerable to Invader Species • Climate similar to habitat of invader • Absence of predators on invading species • Early successional systems • High dispersal rate • Release growth-inhibiting chemicals into soil • Low diversity of native species • Absence of fire • Generalists • High genetic variability • Disturbed by human activities Fig. 12-12, p. 238 POPULATION GROWTH, POLLUTION, AND CLIMATE CHANGE • Population growth, _________, and pollution have promoted the premature _________ of some species. • Projected ________ _______threatens a number of species with premature extinction. Pollution • Each year pesticides: Example of biomagnification of DDT in an aquatic food chain. – Kill about 1/5th of the U.S. honeybee colonies. – 67 million birds. – 6 -14 million fish. – Threaten 1/5th of the U.S.’s endangered and threatened species. 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 • Some protected species are killed for their valuable parts or are sold live to collectors. • Killing predators and pests that bother us or cause economic losses threatens some species with premature extinction. • Legal and illegal trade in wildlife species used as pets or for decorative purposes threatens some species with extinction. OVEREXPLOITATION • Rhinoceros are often killed for their horns and sold ________ on the ______ ______ for decorative and medicinal purposes. Case Study: Rising Demand for Bushmeat in Africa • Bushmeat hunting has caused the local extinction of many animals in West Africa. • Can spread disease such as HIV/AIDS and ______ ____. Figure 12-13 PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES • International treaties have helped reduce the _____________ ______of endangered and threatened species, but enforcement is difficult. – One of the most powerful is the 1975 Convention on International Trade of Endangered Species (______). • Signed by 169 countries, lists 900 species that cannot be commercially traded. Case Study: The U.S. Endangered Species Act • One of the world’s most far-reaching and controversial environmental laws is the 1973 U.S. __________ ________ ___ (ESA). – ______forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species. – ESA makes it illegal for Americans to engage in commerce associated with or _____ / kill / _______ endangered or threatened species. Case Study: The U.S. Endangered Species Act • Biodiversity hotspots in relation to the largest concentrations of rare and potentially endangered species in the U.S. Figure 12-14 Top Six Hot Spots 1 Hawaii 2 San Francisco Bay area 3 Southern Appalachians 4 Death Valley 5 Southern California 6 Florida Panhandle Concentration of rare species Low Moderate High Fig. 12-14, p. 242 Endangered Species • Because of scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered. Endangered Species • Congress has amended the ESA to help landowners _______ _______ on their land. • Some believe that the ESA should be _________ or __________ while others believe it should be strengthened and modified to focus on protecting ecosystems. • Many scientists believe that we should focus on protecting and sustaining _________ and ecosystem function as the best way to protect species. How Would You Vote? To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment. • Should the Endangered Species Act be modified to protect and sustain the nation's overall biodiversity? – a. No. Protecting entire habitats will only further interfere with the rights of landowners. – b. Yes. Protecting endangered habitats is more efficient and effective than saving individual species. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • The U.S. has set aside 544 federal refuges for wildlife, but many refuges are suffering from environmental degradation. Pelican Island was the nation’s first wildlife refuge. PROTECTING WILD SPECIES: THE SANCTUARY APPROACH • ____ _____, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack ________and _______ space. • Zoos and aquariums can help protect endangered animal species by _________ some individuals with the long-term goal of _____________, but suffer from lack of space and ______. RECONCILIATION ECOLOGY • _____________ _______involves finding ways to share places we dominate with other species. – Replacing ____________ _______with native species. – Maintaining _________ for insect eating _____ can keep down unwanted insects. – Reduction and elimination of ________ to protect non-target __________ (such as vital insect pollinators). Using Reconciliation Ecology to Protect Bluebirds • Putting up bluebird boxes with holes too small for (nonnative) competitors in areas where trees have been cut down have helped reestablish populations. What Can You Do? Protecting Species • Do not buy furs, ivory products, and other materials made from endangered or threatened animal species. • Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics. • Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild. • Do not buy orchids, cacti, and other plants that are taken from the wild. • Spread the word. Talk to your friends and relatives about this problem and what they can do about it. Fig. 12-16, p. 249