Chapter 11

Chapter 11

Chapter 11 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 books e-resources page at to access InfoTrac articles. InfoTrac: Domestic cats serve as add-on predators. Paducah Sun (Paducah, KY), July 26, 2006. InfoTrac: Invasion of the habitat snatchers. Wichita

Eagle, August 6, 2006. InfoTrac: Group pulls for native Denali plants. Anchorage Daily News, June 26, 2006. 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 overharvest and habitat loss. Figure 11-1 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. 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. Global Extinction Some animals have become prematurely extinct because of human activities. Figure 11-2

Passenger pigeon Great auk Dodo Dusky seaside sparrow Aepyornis (Madagascar) Fig. 11-2, p. 223 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. Figure 11-3 Fig. 11-3, p. 224 Grizzly bear Utah prairie dog

Kirklands warbler Knowlton cactus Florida manatee Swallowtail butterfly Humpback chub

Golden lion tamarin African elephant Siberian tiger Fig. 11-3, p. 224 Giant panda Black-footed Whooping crane ferret Mountain gorilla Florida panther

California condor Northern spotted owl Hawksbill sea turtle Blue whale Black rhinoceros Fig. 11-3, p. 224 SPECIES

EXTINCTION Some species have characteristics that make them vulnerable to ecological and biological extinction. Figure 11-4 Characteristic Low reproductive

rate (K-strategist) Specialized niche Narrow distribution Examples Blue whale, giant panda, rhinoceros Blue whale, giant panda, Everglades kite Many island species, elephant seal, desert pupfish Feeds at high trophic Bengal tiger, bald eagle, grizzly bear level

Fixed migratory patterns Blue whale, whooping crane, sea turtles Rare Many island species, African violet, some orchids Commercially valuable Snow leopard, tiger, elephant, rhinoceros,

rare plants and birds Large territories California condor, grizzly bear, Florida panther Fig. 11-4, p. 225 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 worlds threatened species. The 2004 Red List contains 15,589 species at risk for extinction. Figure 11-5 SPECIES EXTINCTION Percentage of various species types

threatened with premature extinction from human activities. Figure 11-5 34% (51% of freshwater species) Fish 25% Mammals 20% Reptiles

Plants Birds 14% 12% Fig. 11-5, p. 225 SPECIES EXTINCTION Scientists use models to

estimate the risk of particular species becoming extinct or endangered. Figure 11-6 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 Fig. 11-6, p. 226 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). HABITAT LOSS, DEGRADATION, AND FRAGMENTATION

Conservation biologists summarize the most important causes of premature extinction as HIPPO: Habitat destruction, degradation, and fragmentation 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 11-7 Habitat Pollution Overfishing loss

Habitat degradation Commercial hunting Climate change and fragmentation and poaching Introducingnonnativ Sale of exotic Predator and pest control e species petsand decorative plants Secondary Causes Population growth Rising resource use No environmental

accounting Poverty Basic Causes Fig. 11-7, p. 229 HABITAT LOSS, DEGRADATION, AND FRAGMENTATION Reduction in ranges of four wildlife species, mostly due to habitat loss and

overharvest. Figure 11-8 Indian Tiger Range 100 years ago Range today (about 2,300 left) Fig. 11-8a, p. 230 Black Rhino Range in 1700 Range today (about 3,600 left) Fig. 11-8b, p. 230

African Elephant Probable range 1600 Range today Fig. 11-8c, p. 230 Asian or Indian Elephant Former range Range today (34,00054,000 left) Fig. 11-8d, p. 230 Case Study: A Disturbing Message from the Birds

Human activities are causing serious declines in the populations of many bird species. Figure 11-9 Cerulean warbler Florida scrub jay Spragues pipit California gnatcatcher

Bichnells thrush Black-capped vireo Kirtlands warbler Henslows sparrow Golden-cheeked warbler Bachmans warbler Fig. 11-10, p. 232 Case Study: A Disturbing Message from the Birds The

majority of the worlds bird species are found in South America. Threatened with habitat loss and invasive species. Figure 11-10 Number of bird species 609

400 200 1 Fig. 11-9, p. 231 INVASIVE SPECIES Many Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats.

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. Figure 11-A INVASIVE SPECIES Many invasive species have been introduced

intentionally. Figure 11-11 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. 11-11a, p. 234 INVASIVE SPECIES Many invasive species have been introduced

unintentionally. Figure 11-11 Accidentally Introduced Species Sea lamprey Argentina (attached to lake trout) fire ant Formosan termite Zebra mussel Brown tree snake

Asian longhorned beetle Eurasian ruffe Asian tiger mosquito Common pigeon (Rock dove) Gypsy moth larvae Fig. 11-11b, p. 234 Fig. 11-11, p. 234

INVASIVE SPECIES The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. Most probably from ships. No natural

predators. Figure 11-12 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. Figure 11-13

What Can You Do? Invasive Species 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 them home. before taking 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, outdoor equipment before heading home. and other 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. Fig. 11-14, p. 236 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. 11-13, p. 236 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

Example of biomagnification of DDT in an aquatic food chain. year pesticides: 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. Figure 11-15 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. 11-15, p. 237 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. Figure 11-16 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. Figure 11-17 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). Signed by 169 countries, lists 900 species that cannot be commercially traded. Case Study: The U.S. Endangered Species Act

One of the worlds 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 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. Figure 11-18 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. 11-18, p. 241 Endangered Species Because of

scarcity of inspectors, probably no more than 1/10th of the illegal wildlife trade in the U.S. is discovered. Figure 11-19 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. 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 nations first wildlife refuge. Figure 11-20 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. 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). 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. Figure 11-B 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. 11-21, p. 246

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