Transcript 2. Mass Extinction

Ch. 5
Biodiversity
and
Conservation
I. Biodiversity
- the variety of life in an area
- As extinction reduces biodiversity,
ecosystem stability decreases.
A. Types of Biodiversity
1.Genetic Diversity
- the variety of genes in a
population (gene pool)
- could include useful genes
such as disease or drought
resistance
A. Types of Biodiversity
1.Genetic
Diversity
2. Species Diversity
- the number and relative
abundance of species in an area
Teosinte
Maize
3. Ecosystem Diversity
- the variety of ecosystems in a
region or the biosphere
3. Ecosystem Diversity
B. Importance of Biodiversity
- biodiversity provides direct and
indirect value to humans
1. Direct Economic Value
- plants and animals provide food,
clothing, energy, medicine,
shelter
1. Direct Economic Value
- also provide sources for new
medicines, crops, useful genes
1. Direct Economic Value
- also provide sources for new
medicines, crops, useful genes
2. Ecosystem Services
- functions provided by nature
that benefit all
humans and
other organisms
- oxygen,
drinking water,
pollination,
flood control,
nutrient cycling
3. Aesthetic and Scientific Value
- Their true value is realized
when they are
lost.
II.Threats to Biodiversity
A. Extinction Rates
1. Background Extinction
- the ‘natural’ rate of extinction
~ 1 species per 1,000 species
per year
2. Mass Extinction
- catrastrophic, global events that
causes extinction of a large
percentage of species
- 5 mass extinctions have occurred.
Diversity of Life and Periods
of Mass Extinction
600
100
500
0
Number of
taxonomic
Permian mass families
extinction
Extinction rate
)
100
2,500
2,000
60
1,500
40
Cretaceous
mass extinction
1,000
Number of families (
80
)
500
Paleozoic
Mesozoic
Cenozoic
Neogene
Paleogene
Cretaceous
Jurassic
Triassic
0
Permian
Devonian
Silurian
Ordovician
Cambrian
0
Carboniferous
20
Proterozoic eon
Extinction rate (
Millions of years ago
400
300
200
2. Mass Extinction
- catastrophic, global events that
causes extinction of a large
percentage of species
- 5 mass extinctions have occurred.
- We are probably witnessing the
6th mass extinction.
B. Factors That Threaten
Biodiversity
- Today’s high extinction
rate is human caused.
~ 1,000 times the background
extinction rate.
Passenger Pigeons, now extinct,
was numbered more than 3.5 billion.
In 1866 one flock of passenger
pigeons was estimated to be 1.5
miles wide and 300 miles long,
taking 14 hours to pass.
1. Overexploitation
- over hunting or harvesting
- especially the ‘charismatic
megafauna’ (panda, rhinos, tigers,
California condor)
- As the species
becomes
increasingly
rare, its value
goes up.
Northern White Rhino,
only 7 survive in the wild
2. Habitat Loss
- deforestation, urbanization,
expanding agriculture
3. Habitat Fragmentation
- Dividing habitats into smaller
parcels reduces species diversity.
- Populations become isolated
reducing genetic diversity.
4. Pollution
- Biomagnification
4. Pollution
- Acid Precipitation
4. Pollution
- Eutrophication
4. Pollution
- Eutrophication
5. Introduced Species
5. Introduced Species
- Exotic species lack natural enemies.
- can outcompete native species
In 1859, an Australian
farmer introduced 24
grey rabbits to remind
him of home. By the
1930’s the rabbit
population increased
to 600 million. In 1950
Myxomatosis virus was
introduced, las in this
government dug water
hole and the
population was
reduced to “only” 100
million.
5. Introduced Species
- Exotic species lack natural enemies.
- can outcompete native species
Kudzu overgrowing a house in S. Carolina.
5. Introduced Species
- Exotic species lack natural enemies.
- can outcompete native species
Asian or Silver Carp, some
over 100 pounds, were
originally imported from
China to clear algae from
catfish ponds. Flooding
allowed some into the
Mississippi River and its
tributaries where
populations have exploded.
5. Introduced Species
Burmese Python
Red Lion Fish
Cane Toad
III. Conserving Biodiversity
A. Natural Resources
- As human population grows,
demand for resources increases.
- Consumption is higher in
industrial nations.
- As developing countries become
more industrialized, consumption
rates increase.
On average, one American consumes as
much energy as:
2
Japanese
6
Mexicans
13 Chinese
31 Indians
128 Bangladeshis
307 Tanzanians
370 Ethiopians
Ecological Footprint in Relation
to Available Ecological Capacity
Ecological footprint (ha per person)
16
14
12
New Zealand
10
8
Australia
Canada
Sweden
Japan Netherlands
Norway
6
UK
Spain
4
2
0
USA
Germany
World
China
India
0
2
4
6
8
10
Available ecological capacity
(ha per person)
12
14
16
1. Renewable Resources
- replaced by natural processes
faster than they are consumed
- sunlight, timber, clean air and water
2. Nonrenewable Resources
- limited supply, replaced by nature
very slowly
- fossil fuels, minerals, old-growth
forest
3. Sustainable Use
- rate of resource consumption equals
replacement rate
B.Protecting Biodiversity
1. U.S. Protected Areas
- National Parks, Wildlife Refuges,
Wilderness Areas, etc.
2. International Protected Areas
- Biosphere Reserves, World Heritage
Sites, National Parks
~ 7% of world’s land
Nanda Devi Biosphere Reserve,
Uttarakhand, India
Biosphere Reserves
2. International Protected Areas
- Biosphere Reserves, World Heritage
Sites, National Parks
~ 7% of world’s land
3. Biodiversity Hot Spots
- regions of exceptional diversity
3. Biodiversity Hot Spots
- regions of exceptional diversity
- 34 areas recognized internationally
- contain >1500 species of endemic
plants and 70% of habitat lost
4. Habitat Corridors
- connect fragmented habitats
- increases species and genetic
diversity
‘Migration Corridor’ for herptofauna
‘Wildlife Bridge’ in Netherlands
‘Toad Tunnel’ in England
C. Restoring Ecosystems
- speeding up a damaged ecosystem’s
recovery
Bioremediation
- Bacteria and plants have been used
to remove or immobilize pollutants.
D.Legally Protecting
Biodiversity
- Endangered Species Act (1973)
protects endangered species in U.S.
- CITES (Convention on International
Trade in Endangered Species of Wild
Flora and Fauna (1975)
The
End