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BIODIVERSITY
• Includes a variety of factors Genetic Diversity – genetic variability
within a species Species Diversity – variety of different
species- Species Richness - Total number of species in a community.
Ecological Diversity – variety of abiotic and biotic factors
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Factors That Increase Biodiversity
• Diverse habitat• Moderate environmental disturbance• Small variations in environmental
conditions• Middle stages of succession• Evolution
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Factors That Decrease Biodiversity
• Environmental Stress• Large environmental disturbance• Extreme environmental conditions• Introduction of alien species• Geographic isolation• Severe limitation of essential
resources
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How Many Species Are There ?
• Currently 1.7 million species identified.
• Estimates range between 3-50 million. May be 30 million insect species. Invertebrates make up 70% of all
known species, and probably most of yet to be discovered species.
• Tropical rainforests and coral reefs are biodiversity hotspots. NA and Europe only contain 10-15%.
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BENEFITS OF BIODIVERSITY
• Food As many as 80,000 edible wild plant
species could be utilized by humans.• Drugs and Medicines
> ½ of all prescriptions contain some natural product.
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Benefits of Biodiversity
• Ecological Benefits Soil formation, waste disposal, air and water
purification, nutrient cycling, solar energy absorption, and biogeochemical and hydrological cycles
• Aesthetic and Cultural Benefits Cultural diversity linked to biodiversity. USFWS estimates Americans spend $104
billion annually on wildlife-related recreation.
Ecotourism Intrinsic value.
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THREATS TO BIODIVERSITY
• Extinction - Elimination of a species. Natural Causes
- In undisturbed ecosystems, ~ one species per decade.
In this century, human impacts have accelerated that rate, causing perhaps hundreds to thousands of extinctions annually.
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Human-Caused Threats to Biodiversity
• Habitat Destruction Biggest reason for current increase
in extinction- Habitat fragmentation divides populations into isolated groups
Northern Spotted Owl
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Human-Caused Reductions in Biodiversity
• Alien Species Thrive in new territories-free of
predators, diseases, or resource limitations that limited them in original habitat.
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Human-Caused Reductions in Biodiversity
• Pollution Pesticides Lead
• Population Human population growth
- Resource Use• Overharvesting
American Passenger Pigeon Whales
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Human-Caused Reductions in Biodiversity
• Commercial Products and Live Specimens Wildlife smuggling is very profitable.
- Leopard fur / Rhinoceros horns U.S. Annual pet trade in wild species:
- 2 million reptiles- 1 million amphibians and mammals- 500,000 birds- 128,000,000 tropical fish
Cyanide released above coral reefs.
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Human-Caused Reductions in Biodiversity
Predator and Pest Control• Many animal populations have been
greatly reduced or exterminated because they are regarded as dangerous to humans or livestock. Animal control costs $20 million in
federal and state funds annually.- 700,000 birds and mammals annually.
100,000 coyotes
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Solutions to Protecting Wild Species
• Endangered Species Act-1973 Conservation of threatened and
endangered plants and animals and the habitats in which they are found
Endangered- are those considered in imminent danger of extinction.
Threatened are those likely to become endangered, at least locally, in the near future.
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Endangered Species Act
• Regulates the following activities involving endangered species: Taking (harassing, harming, pursuing,
hunting, shooting, killing, capturing, or collecting) either accidentally, or on purpose.
Selling Importing into or Exporting out of the
U.S. Possessing Transporting or Shipping
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Endangered Species Act
• Currently, U.S. has 1,300 species on its Endangered and Threatened lists, and about 250 candidate species waiting for consideration. Number reflects more about human
interests than actual status.- Invertebrates make up 75% of all species, but only 9% of T/E list.
Listing process is extremely slow.
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Recovery Plans
• Once a species is listed, USFWS is required to propose a recovery plan detailing the rebuilding of the species to sustainable levels. Total cost of all current plans = $5
billion.- Some have been very successful.
• Opponents have continually tried to require economic costs and benefits be incorporated into planning.
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Solutions to Protecting Wild Species
• International treaties Convention on International Trade in
Endangered Species (CITES)- Bans hunting, capturing and selling of
endangered and threatened species • Egg pulling-collecting wild eggs laid by
critically endangered species and hatching them in zoos or research centers
• Captive breeding-bred in captivity with the aim of reintroducing the offspring into the wild
• Wildlife Management Population management plans Saving critical habitat especially for
migratory species