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Chapter 11: Biodiversity Conservation
11.1 What Is Biodiversity?
• Biodiversity
• Variety of life in all forms, combinations, and
organization
– Landscape biodiversity (ecological)
– Community biodiversity (species)
– Population biodiversity (genetic)
BIODIVERSITY
• Biodiversity - Variety of living things.
– Genetic Diversity - Measures variety of
different versions of same genes.
– Species Diversity - Measures number of
different kinds of organisms within a
community.
– Ecological Diversity - Measures richness and
complexity of a community.
11.1 What Is Biodiversity?
• Landscape biodiversity
– Variety and abundance of species from place
to place
• Pattern driven by two factors
– Gradual change in environmental factors
• Temperature
• Growing seasons
• Water availability
– History of local disturbance
• Fire/flood cycles
11.1 What Is Biodiversity?
• Community biodiversity
• Number of species, their relative abundance and
arrangement in space
– Species richness
• Total number of species in an area
– Species evenness
• Relative abundance of the species in a community
• Structural complexity
• Three-dimensional distribution of species and
biological features
11.1 What Is Biodiversity?
• Population biodiversity
– Measured by genetic diversity
• Genetic variation among individuals
– Outbreeding
• Mating with nonrelated individuals
• Maximizes diversity
– Inbreeding
• Mating between closely related individuals
• Increases chance of genetic disease and
reproductive failure
How Many Species
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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.
 North America and Europe only contain
10-15%.
11.2 Why Biodiversity Matters
• Importance of biodiversity
– Helps ecosystems respond to
disturbance/change
– Provides humans with many ecosystem
services
– Improves production of goods
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Food
Fuel
Fiber
Medicine
BENEFITS OF BIODIVERSITY
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Food
 As many as 80,000 edible wild plant
species could be utilized by humans.
Drugs and Medicines
 More than half of all prescriptions contain
some natural product.
 Pharmaceutical products derived from
developing world, plants, animals, and
microbes to be more than $30 billion/year.
BENEFITS OF BIODIVERSITY CONT’D
•
Ecological Benefits
 Soil formation, waste disposal, air and
water purification, nutrient cycling, solar
energy absorption, and food production
and hydrological cycles all depend on
biodiversity.
- At least $33 Trillion annual benefit.
 Can a system function without all its
integral parts?
BENEFITS OF BIODIVERSITY CONT’D
•
Aesthetic and Cultural Benefits
 Cultural diversity inextricably linked to
biodiversity.
 USFWS estimates Americans spend $104
billion annually on wildlife-related
recreation.
 Ecotourism can be an important form of
sustainable economic development.
 Existence (intrinsic) value.
11.2 Why Biodiversity Matters
• Ecosystem function and service
– Depends on individual species and
interactions
– Species vary with regard to importance
• Example: Producers more abundant
– Complementarity effect
• Resources used by various species in a
complementary fashion
• More efficient
11.2 Why Biodiversity Matters
• Ecosystem stability
– Biodiversity enables ecosystem to
resist/recover from changes or disturbance
• Diverse ecosystems have many species with
varying tolerances
– Enhances ecosystem ability to survive disturbance or
change
11.2 Why Biodiversity Matters
• Economic value
• Biodiversity provides essential goods and
services
– Food
– Fiber
– Ecotourism
– Medicine
– Biotechnology
11.2 Why Biodiversity Matters
• Existence value
– Intrinsic value of plants and animals
– Religious beliefs
– Ethics
• United Nations Charter for Nature
– "Every form of life is unique, warranting respect . . ."
11.3 Global Patterns of Biodiversity
• Earth supports 7–15 million species of
eukaryotes
• Only 10–20% have been described
– Terrestrial
• Over 80% animals, most insects
– Marine
• Almost 50% algae
11.3 Global Patterns of Biodiversity
• Species richness
– Generally, number of species in biomes
decreases with distance from equator
• Global pattern based on 4 factors
– Net primary production
– Past disturbance
– Habitat gradients
– Ecosystems complexity
11.3 Global Patterns of Biodiversity
• Biodiversity hotspots
– Large number of endemic species
– Human actions threaten habitats
• Conservation International
– Uses biodiversity hotspots to prioritize
activities
– Defines hotspots as area having at least
1,500 endemic species with at least 70% of
original area altered by humans
11.4 Differences in Biodiversity among
Communities
• Biodiversity varies among ecological
communities
• Enhanced by differences
– Habitat diversity
– Species interactions
– Disturbance
– Immigration/extinction
11.4 Differences in Biodiversity among
Communities
• Habitat diversity
– Greater habitat diversity supports more
species
– Varying topography creates differing habitats
• Mountains, rivers, valleys
– Habitat complexity supports more niches
• Greater species diversity
11.4 Differences in Biodiversity among
Communities
• Species interactions
– Competition and predation influence
biodiversity
• Predators
– Prey species cannot become dominant to exclude
competitors
• Herbivores
– Drive adaptation and increases diversity of plants
11.4 Differences in Biodiversity among
Communities
• Disturbance
– Biodiversity peaks at intermediate level of
disturbance
– Disturbance acts like an herbivore
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Prevents any one species from dominating
Fire
Flood
Hurricanes
11.4 Differences in Biodiversity among
Communities
• Local immigration and extinction rates
– Species richness affected by both
• Equilibrium theory of island biogeography
– R.H. MacArthur and E.O. Wilson
– Species diversity on islands determined by 2
factors
• Rate of new species migration
• Rate of species disappearing from island
• Certain habitats act as islands
THREATS TO BIODIVERSITY
•
Extinction - Elimination of a species.
 Normal Process
- In undisturbed ecosystems, background
rate appears to be one species per
decade.
 In this century, human impacts have
accelerated that rate, causing perhaps
hundreds to thousands of extinctions
annually.
Natural Causes of Extinction
•
Fossil record suggests more than 99% of all
species ever in existence are now extinct.
 Most went extinct before humans arrived.
- End of Cretaceous period - Dinosaurs
and 50% of existing genera
disappeared.
- Permian period - Two-thirds of all marine
species and nearly half of all plant and
animal families died out.
Human-Caused Reductions in Biodiversity
•
Habitat Destruction
 Biggest reason for current increase in
extinction is habitat loss.
- Habitat fragmentation divides
populations into isolated groups
vulnerable to catastrophic events.
 Island Biogeography
 Species diversity is a balance
between colonization and
extinction.
Habitat Fragmentation - Cadiz Township, WI
Human-Caused Reductions in
Biodiversity Cont’d
•
Hunting and Fishing
 Overharvesting of game species.
- American Passenger Pigeon
- American Bison
- Whales
- Atlantic Cod
•
Human-Caused Reductions in
Biodiversity Cont’d
Commercial Products and Live Specimens
 Wildlife smuggling is very profitable.
- 50 deaths for every live arrival at market.
 U.S. Annual pet trade in wild species:
 2 million reptiles
 1 million amphibians and mammals
 500,000 birds
 128 million tropical fish - often
caught with cyanide above coral
reefs.
Endangered Species Parts
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
Predator and Pest Control Cont’d
•
Exotic Species Introductions
 Exotic organisms - Organisms introduced
into habitats where they are not native.
- Biological Pollution
 Kudzu Vine
 Leafy Spurge
 Purple Loosestrife
 Zebra Mussels
 Asian Long-Horned Beetles
Predator and Pest Control Cont’d
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Diseases
 When a disease is introduced into a new
environment, natural balance may be
tipped, leading to an epidemic.
- Chestnut Blight, Whirling Disease
Pollution
 Toxic Pollutants
- Pesticides, Lead , DDT
Genetic Assimilation
11.5 Threats to Biodiversity
• Human activities increasing extinction rate
– Habitat loss/destruction
– Habitat fragmentation
– Overharvesting
– Non-native invasive species
– Pollution
– Altered patterns of disturbance
– Climate change
About 200 years ago,
the American passenger
pigeon was probably the
world's most abundant
bird.
Population: 3-5 billion
Over hunting and
habitat destruction
caused its extinction.
11.5 Threats to Biodiversity
• Habitat loss
– Single greatest threat to biodiversity
• 82% of endangered bird species from habitat loss
• Logging, agriculture, and development
– 95% of North American deciduous forest
lost/altered
– 3% of U.S. mixed and tall grass prairie remain
11.5 Threats to Biodiversity
• Habitat fragmentation
– Habitats are divided into small disconnected
habitats
• Roads
• Developments
• Dams
– Many behave as islands
– Reduces or eliminates movement or dispersal
– Reduces gene flow
11.5 Threats to Biodiversity
• Overharvesting
– Human consumption reduces population
• Food, industry, pet trade
– When harvested faster than can reproduce,
species population will crash
– Certain species vulnerable
• Slow population growth rates
• Flocking/schooling behavior
• Large bodied
Trade in Wildlife
About 75% of all saltwater tropical aquarium fish sold come from coral reefs of the Philippines
and Indonesia, where they are commonly caught with dynamite or cyanide.
11.5 Threats to Biodiversity
• Non-native invasive species
– Population explodes and
outcompetes/displaces natives
• Lack of predators/pathogens
• Lack of competitors
• Own adaptations
• May disrupt food web or species
composition
Introduced Species
• If introduced species prey upon, or
compete more successfully than, native
populations, the nature of the
community may be altered
– Human history littered with examples of
introducing exotic species to solve
problems caused by previous introductions
• Mongoose and Rats in Caribbean
Cane Toad
11.5 Threats to Biodiversity
• Pollution
– Air and water pollution remove species
– Pollutants may build up through food web
• Altered patterns of disturbance
– Changes of frequency and intensity
• Floods
• Fire
– Changes species composition
11.5 Threats to Biodiversity
• Climate change
– Shifting weather patterns alter or eliminate
habitat
• Disappearing sea ice
– Polar bear habitat
– Warmer seas
• Coral bleaching
Protecting Biodiversity
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Hunting and fishing laws
The Endangered Species Act (ESA)
Recovery plans
Reintroductions
Minimum viable population
Private land and critical habitat
Reauthorization of the ESA
International wildlife treaties
11.6 Strategies for Conserving Biodiversity
• Effective conservation of diversity requires
multiple strategies
– Preserves and protected areas
• Health of individual species population
• Management of habitat
– Maximizing migration
– Maintaining cycles
– Mitigating human influence
11.6 Strategies for Conserving Biodiversity
• Preserves and protected areas
• Behave as islands
• Depend on principles of island biogeography
– Size
• Larger preserves support more species
– Connectivity
• Migration corridors
– Distance from other preserves
– Buffers
• Protect from human influence/disturbance
11.6 Strategies for Conserving Biodiversity
• Managing populations of individual
species
– Requires restoration and maintenance of
healthy populations
• Population viability
– Probability of extinction in a given number of years
• Affected by several factors
– Availability and quality of habitat
– Size of population
– Disease/predators
• Umbrella species
– Species whose protection protects other species that
require similar habitat
11.7 U.S. Policies for Conserving
Biodiversity
• National parks and wilderness areas
– Park system set high standard for managing
biodiversity
– Established for protection of habitat and
preservation for human use
• Parks protect sensitive habitat
• Some suffer from overuse/visitation
BIODIVERSITY PROTECTION
•
Hunting and Fishing Laws
 By 1890’s, most states had enacted some
hunting and fishing laws.
- General idea was pragmatic, not
aesthetic or moral preservation.
 White-tailed deer
 Wild turkeys
 Wood ducks
11.7 U.S. Policies for Conserving
Biodiversity
• Legislation to protect species
– U.S. laws limit commerce and injury to threatened
and endangered species
• 1900 Lacey Act
– Prohibits trade in wildlife, fish, or plants taken illegally
• U.S. Fish and Wildlife Service
– Created to enforce Lacey Act
– Endangered Species Act
• Prohibits taking of endangered or threatened species
regardless of landownership.
Endangered Species Act
•
Established in 1973.
 Endangered are those considered in
imminent danger of extinction.
 Threatened are those likely to become
endangered, at least locally, in the near
future.
- Vulnerable are those that are naturally
rare or have been locally depleted to a
level that puts them at risk.
Endangered Species Act Cont’d
•
ESA regulates a wide range of 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
Endangered Species Act Cont’d
•
Currently, the U.S. has 1,300 species on its
endangered and threatened lists, and 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% worthy of
protection.
 Listing process is extremely slow.
Recovery Plans
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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.
Opponents have continually tried to require
economic costs and benefits be incorporated
into planning.
Minimum Viable Populations
•
Minimum Viable Population is the minimum
population size required for long-term
viability of a species.
Minimum Viable Populations Cont’d
•
Diversity Loss in Small Populations:
 Founder Effect
- Few individuals start a new population.
 Demographic Bottleneck
- Few individuals survive catastrophe.
 Genetic Drift
- Random reduction in gene frequency.
 Inbreeding
- Mating between related individuals.
Private Land and Critical Habitat
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Private land is essential in endangered
species protection.
 Eighty percent of habitat for more than half
of all listed species is on nonpublic
property.
Habitat Conservation Plans (HCP)
 Landowners are allowed to harvest
resources or build on part of their land as
long as the species benefits overall.
Reauthorizing ESA
•
ESA officially expired in 1992.
 Proposals for new ESA generally fall into
two general categories:
- Versions that encourage ecosystem and
habitat protection rather than individual
species.
- Safe Harbor policies that allow exceptions
to critical habitat designations.
 (Economic Considerations)
11.8 International Policies for Conserving
Biodiversity
• Convention on International Trade in
Endangered Species of Wild Fauna and Flora
– Known as CITES
– Has slowed the overhunting and collection of many
plants and animals
– Effectiveness debatable
• Black market
– Other international treaties
• International Convention on the regulation of whaling
11.8 International Policies for Conserving
Biodiversity
• Economic incentives for conservation
– Many hotspots in poor developing nations
– Ecotourism
– Debt-for-nature swaps
• International debt forgiven for creation of preserves
and parks