Sustaining wild species and biodiversity
What major factors affect biodiversity?
1. Factors that tend to increase biodiversity.
A. A physically diverse habitat.
B. Moderate environmental disturbance.
C. Small variations in environmental conditions such as nutrient supply, precipitation, and
temperature.
E. Evolution
2. Factors that tend to decrease biodiversity.
A. Environmental stress.
B. A large environmental disturbance.
C. Extreme environmental conditions.
D. Severe limitation of an essential nutrient, habitat, or other resource.
E. Introduction of a non-native species
F. Geographic isolation.
How have human activities affected global biodiversity?
1. Degraded or disturbed 40 – 50 % of earths land surface.
2. Waste or destroy about 27% of earth’s total potential net primary productivity, and 40% of
the net primary productivity of terrestrial ecosystems.
3. Lost about half of the world’s wetlands over the past century.
4. Logging and land conversion have reduced global forest cover by at least 20% and possibly
more.
5. Approximately 27% of the world’s coral reefs have been severely damaged.
6. Estimates of current global extinction rates are at least 100 (probably close to 1000 – 10,000)
times what it was before humans existed.
A. 34 % of fish species (51% freshwater species), 25% of amphibians, 24% of mammals,
20% of reptiles, 14% of plants, and 12% of bird species are threatened with
premature extinction.
B. Approximately 33% of the 21,000 known species in the United States are vulnerable to
premature extinction.
C. 95 – 98 % of the virgin forests in the lower 48 states have been destroyed since 1620.
D. 98% of the tall grass prairies in the Midwest and Great Plains have disappeared.
E. 99% of California’s native grasslands, 91% of its wetlands, 85% of its redwood forests
are gone.
F. 90% of Hawaii’s dry forests have disappeared.
“The natural world is everywhere disappearing before our eyes – cut to pieces, mowed down, plowed
under, gobbled up, replaced by human artifacts” Edward O. Wilson, 2001
Species extinctions
1. Local extinctions – Often involve loss of one or more populations.
2. Ecological extinction – So few are left that they no longer fill their ecological role.
3. Biological extinction – Species is no longer found anywhere on earth.
Endangered species – has so few survivors that the species could become extinct over all or most of its
natural range.
Threatened or vulnerable species – still abundant in its natural range but if trends continue it is likely
to become endangered.
Estimating extinction rates
1. Determined by the interplay of speciation and extinction.
2. Evolutionary biologists estimate that 99.9% of all species that ever existed are extinct.
A. background extinction – low rate of species loss. 1 – 10% of species per million years, or roughly
1 species per million species per year.
B. mass extinctions – take place over thousands to several million years. 25 – 70 % of species are
wiped out.
C. mass depletion – extinction rate is higher than background but not high enough to be a mass
extinction.
D. extinction spasm – species lost over a few centuries to 1,000 years at most.
3. Fossil and geologic evidence indicate that there have been two mass extinctions and three mass
depletions over the past 500 million years.
A. End of Permian period (250 million years ago) 90% of marine animals disappeared.
B. End of Cretaceous (65 million years ago) 50% of marine species and the dinosaurs disappeared.
4. Fossil records suggest that it takes 5 million years or more after mass extinctions or depletions for
adaptive radiation (evolution) to rebuild biodiversity.
If we are headed for a mass extinction or depletion what will happen?
Hypotheses:
1. A temporary outburst of speciation.
2. A proliferation of opportunistic species. Example: rats, roaches, flies.
3. End to large vertebrate species.
4. End to speciation of large vertebrates. Example: elephants, rhinoceroses, apes, big cats, bears.
How have humans affected natural extinction rates?
1. Estimates of extinction rates are based on observations of how the present number of species
present increases with the size of the area.
A. Species / area relationship indicates that a 90% loss in habitat causes a 50% loss of species.
B. Population viability analysis (PVA) – a risk assessment to predict the probability that a
population will persist for a certain number of generations.
C. Minimum viable population (MVP) – smallest number of individuals necessary to ensure the
survival of a population.
D. Minimum dynamic area (MDA) – minimum area of habitat needed to sustain the MVP.
E. Theory of island biogeography –
F. Changes in species diversity as latitude changes.
G. Differing assumptions on the total amount of biodiversity present.
How are we likely to affect such rates in the near future?
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Best estimates of current extinction rates are 0.1% per year (1000 times the rate before we
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arrived).
If there are presently 5 million species we are losing 5000/year.
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In 200 years we would lose 1 million species.
These equates to an extinction crisis that could lead to a mass extinction.
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20% of the world’s plant and animal species could be gone by 2030. Half by the end of the
century.
Why should we care about biodiversity?
Instrumental values
Economic goods –
1. 90% of today’s food crops.
2. 40% of all medicines and 80% of the top 150 prescription drugs.
3. 85% of our antibiotics.
4. Only 3% of the alkaloids from plants have been screened for their use in the fight against
cancer.
5. Bioprospecting – screening yet undiscovered species for there genetic, pharmaceutical and
ecological values.
Ecological services –
1. Photosynthesis
2. Pollination of crops and other plants.
3. Soil formation and maintenance
4. Nutrient recycling
5. Pest control
6. Climate regulation/ moderation of weather extremes.
7. Flood control
8. Drinking and irrigation water.
9. Waste decomposition
10. Absorption and detoxification of pollutants.
11. Purification of air and water
12. Production of lumber, fodder and biomass fuel.
Information –
1. Genetic information in genes.
2. Educational and scientific information by studying genes, species, ecosystems, and ecological
processes.
Recreation –
1. Eco-tourism: example: African lion skin is worth $1000. Alive over a 7 year period the lion
brings in $515,000 in tourism money. Over its lifetime a 60 year old elephant is worth 1 million in tourism
dollars.
Non-utilitarian values –
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Existence
Aesthetic
Bequest
Intrinsic value
A right to exist that is unrelated to their usefulness to humans.
1. Ethical reasons to protect species and ecosystems.
2. Biophilia – a natural affinity for nature.
A. Do you have an affinity for wildlife and wild ecosystems?
B. If so how do you display this love of wildlife in your daily actions?
C. What patterns of your consumption help destroy or degrade wildlife?
Extinction threats
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Habitat loss
The greatest threat to wildlife is habitat loss, degradation and fragmentation.
In order of significance:
o Tropical deforestation is the number one eliminator of species.
o
o
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Destruction of coral reefs and wetlands.
Plowing of grasslands.
Pollution of freshwater streams and lakes, and marine habitats.
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Globally temperate biomes have been affected more than tropical biomes.
In the United States habitat disturbance that threatens endangered species:
1. Agriculture
2. commercial development
3. water development
4. outdoor recreation
5. livestock grazing
6. pollution
Habitat fragmentation
1. Reduced in area
2. Divided into a patchwork of isolated fragments
Non-native species
 Result in $137 billion per year in damages and pest control costs.
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Threaten 49% or more of the 1,200 endangered or threatened species in the US.
Are blamed for 68% of the fish extinctions in the US.
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Examples: Estimated 1 million feral hogs in Florida. They eat food that other
animals need. Uproot agriculture and forestry crops. Cause traffic accidents.
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Feral cats (estimated 30 million) kill about 568 million song birds a year.
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Fire ants – invade cars and cause accidents by attacking drivers. Make crop
fields unplowable. Disrupt phone service and electrical power. Cost the US an estimated
$600 million per year.
Solutions:
1. Identify characteristics that will allow a species to become an invasive species.
2. Better inspections of goods entering into a country.
3. Require ships to discharge ballast and replace with salt water, pump nitrogen into bilge water,
sterilize bilge water.
Hunting and poaching
1. bushmeat – important source of protein for many local people.
2. An estimated $20 billion a year is made in the illegal trafficking of wildlife (second only to drug
smuggling)
Examples: live Mt gorilla ($150,000), gyrfalcon ($120,000), panda pelt ($100,000), chimpanzee
($50,000), Amazon macaw ($30,000).
3. Exotic pets and decorative plants
4. Predators and pest control.
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Climate change and pollution
1. Some wild species may not have enough time to migrate to favorable locations.
Protecting wild species
1. Bioinformatics – Building computer databases, communicating
Examples: Species 2000, Global Biological Information Facility, Natural Heritage Programs
International Treaties –
1. 1975 Convention on International Trade in Endangered Species (CITES)
A. Offers protection to some 900 species.
B. Restrict international trade on approximately 29,000 species.
2. Convention on Biological Diversity
A. Legally binds signatory governments to protect endangered species. Has not been
signed by US. Contains no penalties for noncompliance.
National Laws
1. The Lacey Act – prevents transport of animals (dead or alive) without permits.
2. The Endangered Species Act of 1973 – (amended in 1982 and 1983).
A. Illegal to import or trade any product made from an endangered or threatened species.
Unless used for scientific purposes or to enhance the survival of the species.
B. National Marine Fisheries Advisory – identify and list ocean species as threatened or
endangered.
C. The US Fish and Wildlife Service to identify and list and terrestrial or freshwater
species as threatened or endangered.
D. Safe harbor agreements E. Voluntary candidate conservation agreements –
The sanctuary approach
1. Gene banks, botanical gardens and farms –
2. Zoos and aquariums –
3. Wildlife management –