Download Species

Sustaining Wild Species
Lecture Outlines
Chapter 11
Environment:
The Science behind the
Stories
4th Edition
Withgott/Brennan
This lecture will help you
understand:
• The scope of Earth’s
biodiversity
• Background extinction
rates and mass extinctions
• Causes of biodiversity loss
• The benefits of biodiversity
• Conservation biology
• Conservation of species
• Conservation above the
species level
Review:
Explain the difference in
genetic diversity, species
richness, and ecosystem
diversity.
Levels of biological diversity (biodiversity)
• Humans are reducing Earth’s
diversity of life
• Biodiversity = variety of life
at all levels of organization
– Species diversity
– Genetic diversity
– Population and community
diversity
Central Case: Saving the Siberian Tiger
• Tigers are going extinct
• The last Siberian tigers live in
the Russian Far East mountains
• They are hunted and poached,
and their habitat was destroyed
• International conservation
groups are trying to save the
species from extinction
• Research, education, zoos, and
captive breeding programs help
Plate Tectonic, Earthquakes, and
Volcanoes
What does all this have to do with biodiversity?
What is Biological Diversity?
• What changes have occurred to change the
biodiversity of the earth?
– Background extinction
– Mass extinction
– Adaptive radiation
• What is different today?
Humans are causing this mass
extinction
• Humans have driven
hundreds of species to
extinction
– Dodo bird, Carolina parakeet,
passenger pigeon
• Multitudes of others teeter
on the brink of extinction
– Whooping crane, Kirtland’s
warbler, California condor
The ivory-billed woodpecker
may not be extinct
People have hunted species to
extinction
Extinctions followed human arrival on islands and continents
Importance of Biodiversity
• Biologist estimate that for every 2,000
species that have ever lived, 1,999 of
them are extinct today.
• Currently species extinction is occurring
at a rate of 100 to 1,000 times the
natural rate of background extinction.
Species diversity
• Species - a set of individuals that share certain
characteristics and can interbreed
– Producing fertile offspring
• Species diversity - the number or variety of
species in a particular region
– Richness = the number of species
– Evenness (relative abundance) = the similarity in
numbers between species
• Speciation adds to species richness and
Extinction reduces species richness
Species diversity and evenness
Compared with the boxed area at the top:
Which area has greater species richness? Why?
Which has reduced richness? Why?
Subspecies: the level below a species
• Subspecies = populations of species that occur
in different areas and differ slightly from each
other
– Divergence stops short of separating the species
– Subspecies are denoted with a third part of the
scientific name
Bengal tiger =
Panthera tigris
tigris
Siberian tiger =
Panthera tigris
altaica
Genetic diversity
• Encompasses the differences in DNA among
individuals
• The raw material for adaptation to local conditions
• Populations with higher genetic diversity can survive
– They can cope with environmental change
• Populations with low genetic diversity are vulnerable
to environmental change or disease
• Inbreeding depression = genetically similar parents
mate and produce inferior offspring
– Cheetahs, bison, elephant seals
Ecosystem diversity
• Ecosystem diversity = the number and variety of
ecosystems
– Including different communities and habitats in an
area
• May include habitats, communities, or ecosystems at
the landscape level
– Sizes, shapes, and connections among patches
– Beaches, cliffs, coral reefs, ocean waters
• An area with a variety of vegetation holds more
biodiversity than the same size area with one plant
type
Some groups have more species than others
• Species are not evenly
distributed among taxonomic
groups
– Insects predominate over
all other life-forms
– 40% of insects are beetles
• Groups accumulate species by:
– Adapting to local conditions
– Allopatric speciation
– Low rates of extinction
Insects outnumber all other species
Measuring biodiversity is not easy
• Out of the estimated 3–100 million species on Earth, 1.8
million species have been identified and described
• Most widely accepted estimate of the number of species?
– 14 million
• It is very difficult to know how many species exist
– Small organisms are easily overlooked
– Many species look identical until thoroughly examined
– Many remote spots on Earth remain unexplored
• Entomologist Terry Erwin found 163 beetle species living on
one tree species
Biodiversity is unevenly distributed
• Living things are not
distributed evenly on
Earth
• Latitudinal gradient
= species richness
increases toward the
equator
Canada has 30–100
species of breeding birds,
while Costa Rica has more
than 600 species
Latitudinal gradient has many causes…
• Climate stability, high plant
productivity, no glaciation
– More niches, species
coexistence
• Diverse habitats increase species
diversity and evenness
– Tropical rainforests and
drylands, ecotones
• Human disturbance can increase
habitat diversity
– But only at the local level
Importance of Biodiversity
Economic: crop strains such as the winged
bean plant (page 355), paper, fiber, dyes,
lumber, oils
Some potential new food sources
Importance of Biodiversity
Medical:
drug source, testing for toxicity and
drugs/vaccines
• 80% of the world’s population relies on plants or
plant extracts for medicines.
• At least 40% of all pharmaceuticals come from
the genetic resources of wild plants, mostly
tropical developing countries. Example:
anticancer drugs
• Rosy periwinkle produces chemicals that are
effective against certain cancers --- childhood
leukemia (page 354)
Organisms provide drugs and medicines
• Wild species
produce $150
billion/year of drugs
• Taxol comes from
the Pacific yew tree
– Treats cancer
• Every species that
goes extinct is a lost
opportunity to cure
disease
Species may go extinct before they can help
Gastric brooding frogs went extinct in the 1980s—taking their medical secrets
with them forever
Importance of Biodiversity
scientific knowledge: how life evolved and
functions
genetic engineering – the incorporation of
genes from one organism into an entirely
different species.
*We have skills to transfer genes from one
organism to another but we do not have the
ability to make genes that encode for specific
traits. Why destroy the genetic diversity
when it may hold the solutions?
Importance of Biodiversity
Ecological services: nutrient cycling,
pollination, soil fertility, oxygen production,
climate moderation, waste recycling,
detoxification, pest control, gene
pool/evolution
Remember Earth’s
Capital????
Importance of Biodiversity
Aesthetic and
Recreational
• Ecotourism: wildlife
tourism
• Americans spend 3 times
more to watch wildlife
than to go to movies or
on professional sporting
events
Why Use the Precautionary
Principle?
Aldo Leopold said….“we have little
understanding of the ecological roles of the
world’s identified 1.75 million species and
how to prevent the premature extinction of
species as a result of our activities.”
Estimates are that on average 50 - 200 species
per day become extinct (above the
background extinction rate)
Keystone species
A species that is crucial in determining
the nature and structure of the entire
ecosystem in which it lives; other species
of a community depend on or are greatly
affected by the keystone species, whose
influence is much greater than would be
expected by its relative abundance.
These are most vulnerable
to habitat loss.
Why Use the Precautionary
Principle?
Ecosystems may lose their ability to support
many forms of life because of the
disappearance of local populations of key
organisms
Why Use the Precautionary
Principle?
Mathematical models indicate a time lag of
several generations between habitat loss and
extinction, primarily because habitat loss also
removes potential colonization sites….
If this is true, biologist may be grossly
underestimating the magnitude of
the current biodiversity meltdown!
Three Levels of Extinction
Local Extinction (extirpation): when a species
is no longer found in an area it once inhabited
but is still found elsewhere in the world.
Three Levels of Extinction
Ecological Extinction: Where there are so few
members of a species left that it can no longer
play its ecological roles in the biological
communities where it is found.
Sea Otter
Three Levels of Extinction
Biological Extinction: Occurs when a species is
no longer found anywhere on the earth.
Biological extinction is FOREVER!!!
Endangered vs. Threatened
• What is the difference in the terms
endangered and threatened?
• Endangered: has so few individual survivors
that the species could soon become extinct
over all or most of its natural range.
• Threatened: still abundant in its natural
range but is declining in numbers and is likely
to become endangered. Examples: grizzly
bear, southern sea otter, American alligator
Estimated extinction rate
Current extinction rates are higher
than normal
• The current extinction rate is 100 to 1,000 times greater
than the background rate
• This rate will increase tenfold in future decades
– Human population growth and resource consumption
• The Red List = species facing high risks of extinction
– Mammal species (21%), bird species (12%)
– 17–74% of all other species
• In the U.S., in the last 500 years, 237 animal and 30 plant
species have been confirmed extinct
– Actual numbers are undoubtedly higher
Estimated Extinction Rates
• Average annual extinction rate of Mammal
and Bird species
– 8000 B.C - A.D. 1600 1 species per 1000
– 1600 – 1900 1 species every 4 years
– 1900 – 1975 1 species every year
Estimated Extinction Rates
• Extinction rate of All Species
– 1975
– 1985
– 1990
– 2000
several hundred
several thousand
at least 10,000
20,000 – 50,000
Threatened
Endangered
Extinct
Ten Characteristics of
Extinction-Prone Species
•
•
•
•
•
found in limited areas
small population size
low population density
large body size
specialized niches and feeding habits --- Giant
Panda (bamboo)
• low reproductive rates
Ten Characteristics of
Extinction-Prone Species
• fixed migrations
Flyway – An established route that ducks, geese,
and shorebirds
follow during
their annual
migrations.
Ten Characteristics of
Extinction-Prone Species
• feed at the top of long food chains or webs
• have high economic value to people
• need large territory :
The California Condor
(page 357)
Snow Leopard Coat
Three Root Causes of
Extinction of Wildlife:
• human population growth
• economic systems that don’t value
the environment
• exploitation, degradation of wildlife
habitats
Human Activities Which Directly
Increase the Wildlife Extinction Rate:
• population growth
• poverty
• habitat loss
Example: The dusky seaside sparrow found
only in the marshes of St. Johns River in Fla.
became extinct in 1987 due to human
destruction of its habitat.
What Type of Feedback Loop?
Human Activities Which Directly
Increase the Wildlife Extinction Rate:
• habitat fragmentation
• hunting/poaching (Carolina Parakeet, Prairie
Dog)
Habitat fragmentation
• Habitat fragmentation =
gradual, piecemeal
degradation of habitat
– Farming, roads, logging,
etc.
• Continuous habitats are
broken into patches
– Species needing that
habitat disappear
• Landscape-level strategies
try to optimize areas to be
preserved
Habitat loss occurs in every biome
• Habitat loss is responsible for declines for 83% of mammals and
85% of birds
• 99% of U.S. prairies have been converted to agriculture
– Grassland birds have declined 82–99%
Critical population density
• Animals must have minimum viable
population size: below this number the
species’ survival may be jeopardized because
males and females have a difficult time finding
each other. Problems are:
– Death rate exceeds birth rate as population falls
below its critical size
– Remaining small population can easily be wiped
out by fire, flood, disease
Critical population density
• Genetic diversity also decreases because the
resulting smaller gene pool and inbreeding reduce
population’s ability to respond to environmental
changes through natural selection
• An endangered species must number at least 10,000
and often more to maintain its evolutionary potential
for survival.
Human Activities Which Directly
Increase the Wildlife Extinction Rate:
• introduced species (alien species)
Examples: Kudzu, Brown Tree Snake,
Blue Water Hyacinth
**Be familiar with examples
of introduced species to
the US
(
Human Activities Which Directly
Increase the Wildlife Extinction Rate:
• uses as pets/ decorations
• climate change/pollution
Warming has been the greatest in the Arctic
Because of melting ice, polar bears can’t hunt
seals, so they were added to the endangered
species list in 2008
Facts to Know
• Species is considered extinct when it has not
been seen for at least 50 years or when the
last of a few monitored individuals die.
• endemic species: Found no where else on
earth
• range: The area in which a particular species is
found
Causes and consequences of
biodiversity loss
Bioinformatics
• Organizing and storing useful biological
information about wild species using a data
base
• Provides computer tools to find, visualize,
analyze, and communicate biological
information
.
Biophilia
An inherent affinity for the natural world
(love of life)
Facts to Know
• Commercial extinction: Depletion of the
population of a wild species used as a
resource to a level at which it is no longer
profitable to harvest the species.
• Where is declining biological diversity the
greatest problem?
Florida, California, Hawaii Hawaii is #1
Biophilia
E. O. Wilson popularized
the notion of biophilia
We have an emotional bond
with other living things
Facts to Know
Biodiversity Hotspots: Describe relatively small areas of
land that contain an exceptional number of endemic
species and are at high risk from human activities.
Support a great number of
endemic species = species
found nowhere else in the
World. The area must have at
least 1,500 endemic plant species
(0.5% of the world total)
There are 34 global biodiversity hotspots
2.3% of the planet’s land surface contains 50% of the
world’s plant species and 42% of all terrestrial
vertebrate species
Human Causes of Species
Endangerment
Give an examples of:
– habitat destruction, habitat
fragmentation, or habitat degradation
–invasive species (biological pollution)
–pollution
–overexploitation
How Important is the Tropical
Rainforest?
• Cover 7% of the Earth’s surface but has as
many as 50% of the Earth’s species inhabit
them
Tropical Deforestation and Degradation
Primary causes
– Rapid population growth
– Poverty
– Exploitive government policies
– Exports to developed countries
– Failure to include ecological services in evaluating
forest resources
Tropical Deforestation and
Degradation
Secondary causes
– Roads
– Cattle ranching
– Logging
– Tree plantations
– Flooding from dams
– Unsustainable peasant farming
- Mining
- Cash crops
- Oil drilling
What Happens When
Tropical Rainforest Are Destroyed?
• Birds that migrate from North America to the
rain forest in Central America and the
Caribbean have been declining in numbers
faster than other migratory birds
• The forest itself generates much of the rainfall
in tropical rain forest. If half of the existing
rain forest in the Amazon region of South
America were to be destroyed, precipitation in
the remaining forest would decrease.
What Happens When
Tropical Rainforest Are Destroyed?
• As the land became drier, organisms adapted to moister
conditions would be replace by organisms able to tolerate the
drier conditions. Many endemic species would become
extinct.
• Disruption of the evolutionary process.
– Tropical Rainforest have supplied the base of ancestral
organism from which adaptive radiation occurs.
– Are we eliminating nature’s ability to replace its species
through adaptive radiation?
Overfishing
• Tragedy of the commons???
• Commercial fishing methods
Bycatch
• By-catch is the term used for the accidental capture
of non-target species in fishing gear. Humpback
whale entangled in a fishing net.
By-catch
Conservation Biology
The scientific study of how humans impact
organism and the development of ways to
protect biological diversity.
Conservation biology: the search
for solutions
• Conservation geneticists = study genetic
attributes of organisms to infer the status of
their populations
• Minimum viable population size = how small a
population can become before it runs into
problems
• Metapopulations = a network of
subpopulations
– Small populations are most vulnerable to
extinction and need special attention
Conservation Biology
• What are the concepts that guide it?
– Large habitats are more effective at safeguarding
species than several habitat fragments
– Large areas of habitat typically have the potential
to support greater species richness.
– It is better if areas of habitat for a given species
are located close together rather than far apart.
Conservation Biology
– Areas that are inaccessible to humans are better
than human accessible areas.
– It is more effective and more economical to
preserve intact ecosystems in which many species
live than to work on preserving individual species
one at a time.
– Higher priority is given to preserving areas that
are more biologically diverse than others.
(Remember the Hot Spots?)
Three Techniques of Conservation
Biology
1. Ecosystem Approach
• In situ conservation
– Protecting habitats
– Restoring damaged or destroyed habitats
– Preserve balanced populations of species in their
native habitat
– Establish legally protected wilderness areas and
wildlife reserves
– Eliminate or reduce the populations of nonnative
species
Three Techniques of Conservation
Biology
2. Species Approach
• Identify endangered species and give them legal
protection
• Preserve and manage crucial habitats
• Ex situ conservation
– zoos, aquariums, botanical gardens, seed banks
• Reintroducing endangered species to nature
Three Techniques of Conservation
Biology
3. Wildlife Management Approach
• Manages game species by:
– Using laws to regulate hunting
– Establishing harvest quotas
– Developing population management plans
– Using international treaties to protect migrating
game species such as waterfowl
Wildlife Refuges
• Teddy Roosevelt established Pelican Island off
Florida’s Atlantic coast as the 1st wildlife
refuge to protect the brown pelican (1903)
• Now have 508 refuges, 85% are in Alaska
• ¾ are wetlands for protection of migratory
waterfowl
Laws, Acts, and Organizations
•
•
•
•
•
CITES
Lacey Act
Endangered Species Act
Wild Bird Conservation Act
Magnuson Fisheries Management and
Conservation Act
CITES
http://www.youtube.com/watch?v=C_Wpcb7G52I
United States
• Lacey Act (1900)
– The Lacey Act prohibits the transportation of
illegally captured or prohibited animals across
state line. In 1900, illegal commercial hunting
threatened many game species. The original Act
was directed at the preservation of game and wild
birds, making it a federal crime to poach game in
one state with the purpose of selling it in another
state.
Endangered Species Act (1973)
Endangered or threatened species cannot
be hunted, killed, collected or injured in the
United States.
Endangered Species Act
• Endangered Species Act (ESA) (1973) = the primary U.S.
legislation for protecting biodiversity
• It forbids the government and citizens from taking
actions that destroy endangered species or their habitats
– Or trading in products made from endangered species
• The ESA’s goal is to prevent extinction
– Stabilize declining populations
– Enable populations to recover
• In 2010, the U.S. had 1,010 species listed as endangered
and 314 listed as threatened
The Endangered Species Act
•
•
•
•
60% are plants and 40 % are animals.
Hawaii leads this list (298+).
Each year about 85 species are added to the list
Requires all commercial shipments of wildlife and
wildlife products enter or leave the country through
one of nine designated ports.
The Endangered Species Act
• National Marine Fisheries Services (NMFS) identifies
and list endangered and threatened ocean species.
• U.S. Fish and Wildlife Service (USFWS) identifies and
list all other endangered and threatened species.
• Adding or removing a species from the list must be
based on biology, not economic or political reasons
The Endangered Species Act
• Forbids federal agencies to carry out, fund, or
authorize projects that would either
jeopardize, destroy or modify the critical
habitat.
• Fines and jail sentences can be imposed on
private lands to ensure protection of the
habitats of endangered species.
Wild Bird Conservation Act
• Imposed a moratorium on importing rare bird
species
Magnuson Fisheries Management and
Conservation Act
• Gives the federal government authority to
manage fisheries in the zone between 3 and
200 miles off the U.S. shore. There is no limit
on the number of U.S. fishing vessels, but
quotas can be imposed on the quantity of fish
taken.
The Convention on Biological Diversity
• The Convention aims to:
– Provide incentives to conserve biodiversity
– Manage access to and use of genetic resources
– Transfer technology (including biotechnology)
– Promote scientific cooperation
– Assess human effects on biodiversity
– Promote biodiversity education and awareness
– Provide funding for critical activities
– Encourage nations to report on conservation efforts
• Despite some successes, biodiversity is still being lost
Protecting biodiversity: captive breeding
• Captive breeding = individuals are bred and
raised so they can be reintroduced into the wild
– 65 plant and animal species exist only in captivity
• Reintroductions can be controversial
– Ranchers opposed reintroducing wolves to
Yellowstone National Park
– Fragmented habitat must be improved
before releasing animals
Biologists have raised condor
chicks in captivity with the
help of hand puppets that look like
the heads of adult condors
Protecting biodiversity: cloning
• Cloning creates more individuals and saves species
from extinction
– DNA from an endangered species is inserted into an
egg without a nucleus
– The egg is inserted into a closely related species
• Several mammal species have been cloned
– But these efforts are not enough to recreate lost
biodiversity
• Without ample habitat and protection in the wild,
having cloned animals in a zoo does little good
Forensics protects threatened species
• Forensic science (forensics) = analyzes evidence to
identify or answer questions relating to a crime
• Conservation scientists use forensics to protect species
– Researchers use DNA to identify a species or
subspecies and its geographic origin
• Detecting illegal activity helps enforce laws protecting
wildlife
– For example, whale meat is analyzed in Asian
markets
– DNA from killed elephants shows many more were
killed than the Zambian government admitted
Umbrella species protect others
• Conservation biologists use particular species as tools to
conserve communities and ecosystems
• Umbrella species = species that, when protected, also
help protect other, less charismatic species
– Often large species that need large amounts of habitat
– Protecting their habitat automatically protects others
• Flagship species = large and charismatic species used as
spearheads for biodiversity conservation
– The World Wildlife Fund’s panda bear
• Some organizations are moving beyond the singlespecies approach to focus on whole landscapes
Other Solutions
• Biosphere Reserves
• Reintroduction of endangered species
Restoration ecology
• Restoration ecology is the scientific study
supporting the practice of renewing and
restoring degraded, damaged, or destroyed
ecosystems and habitats in the environment
by human intervention and action.
Restoration ecology
• "Here is the means to end the great
extinction spasm. The next century will, I
believe, be the era of restoration in ecology"
--E. O. Wilson, 1992
What Else Can We Do?
• Increase Public Awareness
• Support Research in Conservation
Biology
• Support Establishment of an
International Park System
• Control Pollution
What Else Can We Do?
• Give Economic Incentives
–Fees for Medicinal Drugs
–Ecotourism
–Debt for Nature Swap
–Payments to landowners for protecting
endangered species or reduce their
property tax
Using innovative economic strategies
• Debt-for-nature swap = a conservation organization
pays off a portion of a developing country’s
international debt
• In exchange, the country promises to set aside
reserves to:
– Fund environmental education and
– Better manage protected areas
• The U.S.’s Tropical Forest Conservation Act
– Paid $218 million in debt payments to 13
developing countries for conservation efforts
• Conservation concession = conservation organizations
pay nations to conserve, and not sell, resources