Download 5-1

SUSTAINING THE
MILLER/SPOOLMAN
EARTH | G. TYLER MILLER | SCOTT E. SPOOLMAN
11e
5
Sustaining
Biodiversity:
The Species Approach
© Cengage Learning 2015
5-1 What Are the Trends in Species
Extinction?
• Extinction is a natural process that
sometimes accelerates
– Background extinction
• Natural low rate of extinction
– Species extinction
• Local extinction
• Ecological extinction
• Biological extinction: irreversible loss
© Cengage Learning 2015
According to the UN, the Earth is in the midst
of a mass extinction of life. Scientists estimate
that 150-200 species of plant, insect, bird
and mammal become extinct every 24
hours. This is nearly 1,000 times the “natural”
or “background” rate and, say many biologists,
is greater than anything the world has
experienced since the vanishing of the
dinosaurs nearly 65m years ago.
Case Study ─
The Passenger Pigeon: Gone Forever
• Once one of the world’s most abundant
birds
– Audubon (1813): flock took 3 days to fly over
– Hunted to extinction by 1900
• Contributing factors
– Habitat loss
– Commercial hunting
– Easy to kill: flew in large flocks and nested in
dense colonies
© Cengage Learning 2015
Some Human Activities Are Causing
Extinctions
• Human activity has taken over, disturbed,
or polluted
– 60 to 80 percent of the earth’s land surface
– 50 percent of surface waters
• Current annual extinction rate
– 0.1 percent per year
© Cengage Learning 2015
Some Human Activities Are Causing
Extinctions
• Projected 1.0 percent extinction rate in
next 50 to 100 years may be too low
– Species loss rate and biodiversity losses likely
to increase sharply
– Highly endangered biodiversity centers
already exist
– Many biologically diverse environments have
already been degraded
© Cengage Learning 2015
Science Focus: Estimating Extinction
Rates
• Challenges
– Natural extinction takes a very long time
– Only 2 million species have been identified
– Scientists know little about the ecological
roles of identified species
• Scientists strive to get better data and to
improve mathematical models
© Cengage Learning 2015
Table 11_02
Endangered and Threatened Species Are
Ecological Smoke Alarms
• Endangered species
– So few members that the species could soon
become extinct
• Threatened species (vulnerable species)
– Still enough members to survive, but numbers
declining ─ may soon be endangered
© Cengage Learning 2015
Characteristic
Examples
Low reproductive
rate
Blue whale, giant
panda, rhinoceros
Specialized
niche
Narrow
distribution
Blue whale, giant
panda, Everglades
kite
Elephant seal,
desert pupfish
Feeds at high
trophic level
Bengal tiger, bald
eagle, grizzly bear
Fixed
migratory
patterns
Rare
Commercially
valuable
Large territories
Stepped Art
Fig. 5-3
Blue whale,
whooping crane,
sea turtle
African violet,
some orchids
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
California condor,
grizzly bear, Florida
panther
5-2 Why Should We Care about the Rising
Rate of Species Extinction?
• A diversity of species is a vital part of the
earth’s natural capital
– Reasons to prevent extinctions
• Instrumental value, e.g., pollination, natural pest,
economically valuable products, ecotourism,
genetic information, etc.
• Amount of time required for natural speciation to
rebuild lost biodiversity
© Cengage Learning 2015
Science Focus: Where Have All the
Honeybees Gone?
• Honeybees’ ecosystem service: pollination
– One-third of human food supply from
insect-pollinated plants
– U.S. growers rent European honeybees from
beekeepers
• Colony collapse disorder (CCD)
– Decline in honeybee populations
– Scientists seeking the cause
© Cengage Learning 2015
Rauvolfia
Rauvolfia
sepentina,
Southeast Asia
Anxiety, high
blood pressure
Fig. 5-4
Pacific yew
Taxus
brevifolia,
Pacific
Northwest
Ovarian cancer
Foxglove
Digitalis
purpurea,
Europe Digitalis
for heart failure
Rosy
periwinkle
Cathranthus
roseus,
Madagascar
Hodgkin's
disease,
lymphocytic
leukemia
Cinchona
Cinchona
ledogeriana,
South America
Quinine for
malaria treatment
Neem tree
Azadirachta
indica, India
Treatment of
many diseases,
insecticide,
spermicides
Are We Ethically Obligated to Prevent
Premature Extinction?
• Species’ intrinsic (existence) value
– Inherent right to exist and play its ecological
roles
• Ethical dilemma
– Which species should we protect?
• Biologists urge caution
– True foundation of the earth’s ecosystems
and ecological processes are invisible
microorganisms
© Cengage Learning 2015
How do Humans Accelerate Species Extinction?
• Loss of habitat is the single greatest threat to
species: remember HIPPCO
– Habitat destruction, degradation, and
fragmentation
– Invasive (nonnative) species
– Population growth and increasing use of
resources
– Pollution
– Climate change
– Overexploitation
© Cengage Learning 2015
Indian
Tiger
Range 100 years ago
Range today
African
Elephant
Stepped Art
Fig. 5-6
Probable range 1600
Range today
Black
Rhino
Range in 1700
Range today
Asian or Indian
Elephant
Former range
Range today
Some Deliberately Introduced Species
Can Disrupt Ecosystems
• Most species introductions are beneficial
– Such as corn, wheat, cattle, poultry, and trees
• Nonnative species may have no natural
controls
– Predators
– Competitors
– Parasites
– Pathogens
© Cengage Learning 2015
Some Accidentally Introduced Species
Can Disrupt Ecosystems
• Most arrive from other continents as
stowaways
• Example: Argentina fire ant
– Introduced into the U.S. in the 1930s
– Can overtake native ant populations
– Have killed deer fawns, birds, people allergic
to their venom, etc.
© Cengage Learning 2015
Deliberately Introduced Species
Purple
loosestrife
African honeybee
(“Killer bee”)
Kudzu
Nutria
European wild
boar (Feral pig)
Accidentally Introduced Species
Sea lamprey
Argentina fire
(attached to lake ant
trout)
Fig. 5-7
Burmese python Formosan
termite
Zebra mussel
Case Study: Burmese Pythons Eating
Their Way through the Florida Everglades
• Burmese and African pythons
– Sold as pets
– Dumped in Everglades by some owners
• Reproduce rapidly
• Huge appetites
– Feed on birds, mammals, and some reptiles
• Tens of thousands now in Everglades
– Fear of spreading to other swampy wetlands
© Cengage Learning 2015
Prevention Is the Best Way to Reduce
Threats from Invasive Species
•
•
•
•
•
Prevent them from being introduced
Learn the species’ characteristics
Inspect incoming goods
Pass international laws to prevent transfer
Require cargo ships to be free of invader
organisms before entering ports
• Increase research
• Individual awareness and efforts
© Cengage Learning 2015
Fig. 5-7
Fig. 9-12, p. 202
Other Causes of Species Extinction
•
•
•
•
Human population growth
Overconsumption
Pollution
Climate change
© Cengage Learning 2015
Case Study: Polar Bears and Global
Warming
• 20,000-25,000 in the arctic regions
• Primary winter food
– Seals found on floating ice
• Live on body fat during summer and fall
– Resume hunting when ice expands in winter
• Environmental impact on polar bears
– Shortened winter: shrinking ice
• Placed on threatened species list (2008)
© Cengage Learning 2015
Illegal Killing, Capturing, and Selling of
Wild Species Threatens Biodiversity
• Poaching
• Wildlife smuggling
– For each animal smuggled many others die in
transit
• Prevention through education
– Show financial benefit of preserving a species
as opposed to poaching
© Cengage Learning 2015
Case Study: A Disturbing Message from
the Birds
• Twelve percent of all bird species
– Threatened with extinction
• Species’ loss: main cause is H in HIPPCO
• One-third of 800 bird species in U.S. are
endangered or threatened
• Second leading danger: intentional or
accidental nonnative species’ introduction
© Cengage Learning 2015
Case Study: A Disturbing Message from
the Birds
• Other threats
– Oil spills
– Pesticides and herbicides
– Lead poisoning from shotgun pellets
– Fishing nets
– Climate change
– Overexploitation
• Birds serve as environmental indicators
© Cengage Learning 2015
5-4 How Can We Protect Wild Species
from Extinction from Our Activities?
• International treaties and national laws can
help to protect species
– 1975 Convention on International Trade in
Endangered Species (CITES)
• Signed by 175 countries
– Convention on Biological Diversity (BCD)
• Focuses on ecosystems
• Ratified by 193 countries (not the U.S.)
© Cengage Learning 2015
Case Study: The U.S. Endangered
Species Act
• Endangered Species Act (ESA): 1973
– Amended in 1982, 1985, and 1988
• National Marine Fisheries Service (NMFS)
– Identifies and lists endangered and
threatened ocean species
• U.S. Fish and Wildlife Service (USFWS)
– Identifies and lists all other endangered and
threatened species
© Cengage Learning 2015
Case Study: The U.S. Endangered
Species Act
• Federal agencies (except Defense)
– Forbidden from funding or authorizing projects
that jeopardize endangered or threatened
species
• 2012: 1,374 species officially listed
• USFWS and NMFS
– Prepare recovery plans
• Incentives for private property owners
© Cengage Learning 2015
Case Study: The U.S. Endangered
Species Act
• ESA proponents point out reasons the
agency is not a failure
– Species listed only when in serious danger
– Takes decades to help endangered species
– 2011: average expenditure is 8 cents per U.S.
citizen
© Cengage Learning 2015
Case Study: The U.S. Endangered
Species Act
• Ways to improve ESA
– Greatly increase funding
– Develop recovery plans more quickly
– When a species is first listed, establish the
core of its habitat that is critical for survival
and give that area the maximum protection
• New law needed to focus on sustaining
biodiversity and ecosystem health
© Cengage Learning 2015
We Can Establish Wildlife Refuges
and Other Protected Areas
• 1903: Theodore Roosevelt
– Established U.S. federal wildlife refuge at
Pelican Island, Florida
• 2012: 555 refuges in the National Wildlife
Refuge System
– Most are wetland sanctuaries
– More needed for endangered plants
© Cengage Learning 2015
Seed Banks / Botanical Gardens / Wildlife
Farms Can Help to Protect Species
• Seed banks
– Preserve endangered plants’ genetic material
• Botanical gardens and arboreta
– Living plants
• Farms to raise some endangered or
threatened species for commercial sale
© Cengage Learning 2015
Zoos and Aquariums Can Protect
Some Species
• Long-term goal
– Reintroducing the species into protected wild
habitats
• Techniques for preserving endangered
terrestrial species
– Egg pulling
– Captive breeding
• Non-feasible solutions: limited space and
funds
© Cengage Learning 2015
We Can Use the Principles of
Sustainability to Protect Species
• Actions needed to:
– Prevent the factors that will hasten species’
extinction
– Slow climate change
– Reduce the size and impact of our ecological
footprints
© Cengage Learning 2015