Presentation on theme: "Chapter 7 Sustaining Biodiversity: The Species Approach."— Presentation transcript:
Chapter 7 Sustaining Biodiversity: The Species Approach
Chapter Overview Questions How do biologists estimate extinction rates, and how do human activities affect these rates? Why should we care about protecting wild species? 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?
Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at to access InfoTrac articles. InfoTrac: Domestic cats serve as add-on predators. Paducah Sun (Paducah, KY), July 26, InfoTrac: Invasion of the habitat snatchers. Wichita Eagle, August 6, InfoTrac: Group pulls for native Denali plants. Anchorage Daily News, June 26, Union of Concerned Scientists: Invasive Species PBS: Strange Days on Planet Earth USGS: Nonindigenous Aquatic Species
Core Case Study: The Passenger Pigeon - Gone Forever Once the most numerous bird on earth. In 1858, Passenger Pigeon hunting became a big business. By 1900 they became extinct from over- harvest and habitat loss.
SPECIES EXTINCTION Species can become extinct: Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. Locally: 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 ecological role. Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. Globally (biologically): Species is no longer found on the earth. Globally (biologically): Species is no longer found on the earth.
Global Extinction Some animals have become prematurely extinct because of human activities.
Endangered and Threatened Species: Ecological Smoke Alarms Endangered species: so few individual survivors that it could soon become extinct. Threatened species: still abundant in its natural range but is likely to become endangered in the near future.
Hawksbill sea turtle Giant panda Black-footed ferret Whooping crane Northern spotted owl Blue whale Mountain gorilla Florida panther California condor Black rhinoceros
Some species have characteristics that make them vulnerable to ecological and biological extinction. SPECIES EXTINCTION
Low reproductive rate (K-strategist) Specialized niche Narrow distribution Feeds at high trophic level Fixed migratory patterns Rare Commercially valuable Large territories Characteristic Blue whale, giant panda, rhinoceros Blue whale, giant panda, Everglades kite 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 Examples
SPECIES EXTINCTION Scientists use measurements and models to estimate extinction rates. The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. The 2004 Red List contains 15,589 species at risk for extinction. The 2004 Red List contains 15,589 species at risk for extinction.
SPECIES EXTINCTION Percentage of various species types threatened with premature extinction from human activities.
12% Birds Plants Reptiles Mammals Fish 34% (51% of freshwater species) 25% 20% 14%
SPECIES EXTINCTION Scientists use models to estimate the risk of particular species becoming extinct or endangered.
5 million Number of years until one million species are extinct 100,000 extinct per year 50,000 extinct per year 14,000 extinct per year Number of species existing Effects of a 0.1% extinction rate 5,000 extinct per year 100 million 50 million 14 million
IMPORTANCE OF WILD SPECIES We should not cause the premature extinction of species because of the economic and ecological services they provide. Some believe that each wild species has an inherent right to exist. Some people distinguish between the survival rights among various types of species (plants vs. animals). 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 “HIPPO”: Habitat destruction, degradation, and fragmentation Habitat destruction, degradation, and fragmentation Invasive species Invasive species Population growth Population growth Pollution Pollution Overharvest Overharvest
HABITAT LOSS, DEGRADATION, AND FRAGMENTATION The greatest threat to a species is the loss, degradation, and fragmentation of where it lives.
Introducingnonnativ e species Basic Causes Secondary Causes Population growth Rising resource use No environmental accounting Poverty Predator and pest control Climate change Overfishing Pollution Commercial hunting and poaching Sale of exotic petsand decorative plants Habitat loss Habitat degradation and fragmentation
HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Reduction in ranges of four wildlife species, mostly due to habitat loss and overharvest.
Range 100 years ago Indian Tiger Range today (about 2,300 left)
Range in 1700 Black Rhino Range today (about 3,600 left)
Probable range 1600 African Elephant Range today
(34,000–54,000 left) Asian or Indian Elephant Former range
Case Study: A Disturbing Message from the Birds Human activities are causing serious declines in the populations of many bird species.
Case Study: A Disturbing Message from the Birds The majority of the world’s bird species are found in South America. Threatened with habitat loss and invasive species. Threatened with habitat loss and invasive species.
1 609 Number of bird species
INVASIVE SPECIES Many nonnative species provide us with food, medicine, and other benefits but a a few can wipe out native species, disrupt ecosystems, and cause large economic losses. Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats.
INVASIVE SPECIES Many invasive species have been introduced intentionally.
INVASIVE SPECIES Many invasive species have been introduced unintentionally.
Deliberately Introduced Species Purple loosestrife European starling African honeybee (“Killer bee”) Nutria Salt cedar (Tamarisk) European wild boar (Feral pig) Marine toad (Giant toad) Water hyacinth Japanese beetle Hydrilla
Gypsy moth larvae Accidentally Introduced Species Sea lamprey (attached to lake trout) Argentina fire ant Brown tree snake Eurasian ruffe Common pigeon (Rock dove) Formosan termite Zebra mussel Asian long- horned beetle Asian tiger mosquito
INVASIVE SPECIES The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. Most probably from ships. Most probably from ships. No natural predators. No natural predators.
INVASIVE SPECIES Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread.
Do not allow wild animals to escape. Do not spread wild plants to other areas. Do not dump the contents of an aquarium into waterways, wetlands, or storm drains. When camping use wood near your campsite instead of bringing firewood from somewhere else. Do not dump unused bait into the water. After dogs visit woods or the water brush them before taking them home. After each use clean your vehicle, mountain bike, surfboard, kayaks, canoes, boats, tent, hiking boots, and other gear before heading for home. Empty all water from canoes, kayaks, dive gear, and other outdoor equipment before heading home. Plant a variety of trees, shrubs, and other plants in your yard to reduce losses from invasive species. Do not buy plants from overseas or swap them with others using the Internet. What Can You Do? Invasive Species
Climate similar to habitat of invader Absence of predators on invading species Early successional systems Low diversity of native species Absence of fire Disturbed by human activities Characteristics of Successful 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 Characteristics of Ecosystems Vulnerable to Invader Species
POPULATION GROWTH, POLLUTION, AND CLIMATE CHANGE Population growth, affluenza, and pollution have promoted the premature extinction of some species. Projected climate change threatens a number of species with premature extinction.
Pollution Each year pesticides: Kill about 1/5 th of the U.S. honeybee colonies. Kill about 1/5 th of the U.S. honeybee colonies. 67 million birds. 67 million birds million fish million fish. Threaten 1/5 th of the U.S.’s endangered and threatened species. Threaten 1/5 th of the U.S.’s endangered and threatened species. Example of biomagnification of DDT in an aquatic food chain.
DDT in water ppm, or 3 ppt 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
OVEREXPLOITATION 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 illegally on the black market 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 ebola virus.
PROTECTING WILD SPECIES: LEGAL AND ECONOMIC APPROACHES International treaties have helped reduce the international trade of endangered and threatened species, but enforcement is difficult. One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES). One of the most powerful is the 1975 Convention on International Trade of Endangered Species (CITES). Signed by 169 countries, lists 900 species that cannot be commercially traded.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. Endangered Species Act (ESA). ESA forbids federal agencies (besides defense department) to carry out / fund projects that would jeopardize an endangered species. 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 hunt / kill / collect endangered or threatened species. ESA makes it illegal for Americans to engage in commerce associated with or hunt / kill / collect 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.
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 High Low Moderate
Endangered Species Because of scarcity of inspectors, probably no more than 1/10 th of the illegal wildlife trade in the U.S. is discovered.
Endangered Species Congress has amended the ESA to help landowners protect species on their land. Some believe that the ESA should be weakened or repealed 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 biodiversity 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. 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. 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 Gene banks, botanical gardens and using farms to raise threatened species can help prevent extinction, but these options lack funding and storage space. Zoos and aquariums can help protect endangered animal species by preserving some individuals with the long-term goal of reintroduction, but suffer from lack of space and money.
RECONCILIATION ECOLOGY Reconciliation ecology involves finding ways to share places we dominate with other species. Replacing monoculture grasses with native species. Replacing monoculture grasses with native species. Maintaining habitats for insect eating bats can keep down unwanted insects. Maintaining habitats for insect eating bats can keep down unwanted insects. Reduction and elimination of pesticides to protect non-target organisms (such as vital insect pollinators). Reduction and elimination of pesticides to protect non-target organisms (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.
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. What Can You Do? Protecting Species