Sustaining Biodiversity: The Species Approach

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Chapter 7

• Sustaining Biodiversity The Species Approach

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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?

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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
  www.thomsonedu.com 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

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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.

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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.

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Global Extinction

• Some animals have become prematurely extinct
  because of human activities.

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Aepyornis (Madagascar)
Passenger pigeon
Great auk
Dodo
Dusky seaside sparrow
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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.

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Florida manatee
Grizzly bear
Kirklands warbler
Knowlton cactus
African elephant
Swallowtail butterfly
Humpback chub
Utah prairie dog
Siberian tiger
Golden lion tamarin
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Giant panda
Whooping crane
Northern spotted owl
Blue whale
Black-footed ferret
Mountain gorilla
Florida panther
Hawksbill sea turtle
California condor
Black rhinoceros
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SPECIES EXTINCTION

• Some species have characteristics that make them
  vulnerable to ecological and biological
  extinction.

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Characteristic
Examples
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
Low reproductive rate (K-strategist) Specialized
niche Narrow distribution Feeds at high trophic
level Fixed migratory patterns Rare Commercial
ly valuable Large territories
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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.

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SPECIES EXTINCTION

• Percentage of various species types threatened
  with premature extinction from human activities.

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34 (51 of freshwater species)
Fish
25
Mammals
20
Reptiles
14
Plants
12
Birds
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SPECIES EXTINCTION

• Scientists use models to estimate the risk of
  particular species becoming extinct or endangered.

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Number of species existing
Effects of a 0.1 extinction rate
5,000 extinct per year
5 million
14 million
14,000 extinct per year
50 million
50,000 extinct per year
100 million
100,000 extinct per year
Number of years until one million species are
extinct
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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).

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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

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HABITAT LOSS, DEGRADATION, AND FRAGMENTATION

• The greatest threat to a species is the loss,
  degradation, and fragmentation of where it lives.

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Habitatloss
Pollution
Overfishing
Habitat degradation and fragmentation
Commercial hunting and poaching
Climate change
Introducingnonnative species
Sale of exotic petsand decorative plants
Predator and pest control
Secondary Causes
Population growth Rising resource use No
environmental accounting Poverty
Basic Causes
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HABITAT LOSS, DEGRADATION, AND FRAGMENTATION

• Reduction in ranges of four wildlife species,
  mostly due to habitat loss and overharvest.

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Indian Tiger
Range 100 years ago
Range today (about 2,300 left)
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Black Rhino
Range in 1700
Range today (about 3,600 left)
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African Elephant
Probable range 1600
Range today
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Asian or Indian Elephant
Former range
Range today (34,00054,000 left)
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Case Study A Disturbing Message from the Birds

• Human activities are causing serious declines in
  the populations of many bird species.

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Black-capped vireo
Golden-cheeked warbler
Cerulean warbler
Spragues pipit
Bichnells thrush
Henslows sparrow
Bachmans warbler
Florida scrub jay
California gnatcatcher
Kirtlands warbler
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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.

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Number of bird species
609
400
200
1
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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.
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INVASIVE SPECIES

• Many invasive species have been introduced
  intentionally.

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INVASIVE SPECIES

• Many invasive species have been introduced
  unintentionally.

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Deliberately Introduced Species
European starling
Purple loosestrife
African honeybee (Killer bee)
Salt cedar (Tamarisk)
Nutria
European wild boar (Feral pig)
Japanese beetle
Hydrilla
Marine toad (Giant toad)
Water hyacinth
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Accidentally Introduced Species
Eurasian ruffe
Sea lamprey (attached to lake trout)
Argentina fire ant
Brown tree snake
Common pigeon (Rock dove)
Gypsy moth larvae
Asian long-horned beetle
Asian tiger mosquito
Formosan termite
Zebra mussel
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INVASIVE SPECIES

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

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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.

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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 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.
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Characteristics of Successful Invader Species
Characteristics of Ecosystems Vulnerable to
Invader 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
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
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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.

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Pollution

• Each 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.

Example of biomagnification of DDT in an aquatic
food chain.
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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
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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.

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OVEREXPLOITATION

• Rhinoceros are often killed for their horns and
  sold illegally on the black market for decorative
  and medicinal purposes.

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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.

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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.

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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.

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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.

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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
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Endangered Species

• Because of scarcity of inspectors, probably no
  more than 1/10th of the illegal wildlife trade in
  the U.S. is discovered.

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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.

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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.

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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.
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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.

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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).

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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.

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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.