Part 3: Threats to Biodiversity

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Part 3 Threats to Biodiversity
2
Part 3 Threats to Biodiversity

• Chapter 7 Extinction
• Chapter 8 Vulnerability to Extinction
• Chapter 9 Habitat Destruction, Fragmentation,
  Degradation, Global Climate Change
• Chapter 10 Overexploitation, Invasive Species,
  Disease

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Extinction

• Chapter 7

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Extinct ?

• Globally Extinct
• none alive anywhere in the world
• Extinct in the Wild
• alive only in captivity
• Locally Extinct
• no longer found in a former habitat
• Ecologically Extinct
• reduced numbers cease to impact community
• Living Dead
• nonreproductive individuals still living- none
  others
• Extinct when not seen in 50 years (extant)

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Past Mass Extinctions

• 5 episodes of natural mass extinctions
• Ordovician
• Devonian
• Permian
• 95 Marine animals
• Triassic
• 35 animal families
• Cretaceous
• dinosaurs

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Current, Human Caused Mass Extinction

• Sixth Extinction Episode
• Human caused since 1600 most in last 150 years
• Elimination of large mammals from Australia, N.
  S. America
• 85 species mammals
• 2.1
• 113 species birds
• 1.3
• 21 reptiles
• 2 amphibians
• 23 fish
• 98 invertebrates
• 384 flowering plants

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Background Extinction Rates

• Natural extinction rates
• 1-10 million years
• Current rates are 100 1000 times greater!

8
Extinction Rates on Islands

• Islands have highest species extinction rates
• Predatory species introduced on islands decimate
  local populations
• Brown snake eats bird eggs
• Pet cats eats bird eggs
• Birds, mammals, reptiles
• 80 endemic plants
• Endemiclocation naturally occurring
• Hawaii
• Half extinct species are from islands
• 99 extinctions attributable to human activity

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Extinction Rates in Water

• No documented cases fish or coral species
• 12 species extinct in oceans
• 3 marine mammals
• 5 marine birds
• 4 mollusks
• Significant none the less
• Top predators
• Oceans once considered limitless
• Vast oceans no longer safe havens

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Estimating Extinction Rates with Island
Biogeography Model

• Species-area relationship
• Larger areas have more species
• Greater variety of community types
• Greater geographical isolation
• Farther from mainland
• Greater number of populations per species
• See equation page 175
• SCA to Z power
• C and Z are constants depends on island type

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Figure 7.8 page 176

• Interpret the number of species you can expect on
  the island of Saba compared to Jamaica.

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Box 13 Conserving Endemic Fish in Lake Victoria

• Read the story of Lake Victoria on page 177 and
  summarize the impact of chichlids as endemic
  species after the introduction of other species.

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Extinction Rates Habitat Loss

• Habitat islands
• reserves in sea of altered landscapes
• Habitat loss species loss
• Loss of 50 of island 10 species lost
• Loss of 90 50 species lost
• Loss of 99 - 75 species lost

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Assumptions Generalizations in the Island
Biogeography Model

• Based on typical values for species-area curves
• Groups of species with broad geographical ranges
  (marine species) will have lower rates of
  extinction
• Model assumes all endemic species are eliminated
  from areas
• Some may recolonize
• Species are model assume areas of habitat are
  eliminated at random
• Areas of species richness are sometimes targeted
  for species conservation efforts
• Also for destruction efforts
• Degree of habitat fragmentation may affect
  extinction rates
• Wide ranging species may be unable to maintain
  themsleves
• Exotic species increase in fragmented areas

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Other Methods for Calculating Extinction Rates

• Different Model
• Projected declines in habitat
• Numbers of populations
• Geographical range of well-known individual
  species
• Predicts 15-20 species will go extinct in next
  100 years

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Local Extinctions

• Extirpations across their range
• Restricted to a few pockets of former habitat
• Impoverished communities
• 1 million species
• 5 billion distinct populations
• 200 populations per species
• Some species have a few populations per species,
  some have thousands
• Loss of populations proportion of habitat that
  is lost

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Summary

• More species on Earth than in geological past.
  Current rate of extinction 100-1000 times
  greater.
• Island species have higher rate of extinction.
• Island biogeography model.
• Living dead in fragmented areas.
• Impoverished biological communities.

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Vulnerability to Extinction

• Chapter 8

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Rare Species

• Lives in narrow geographic range
• Occupies only one or a few specialized habitats
• Is found only in small populations

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Endemic Species Extinction

• Endemic
• Species found naturally in a single geographic
  location and no other place
• Size of the geographic location is of importance!
• Dispersal abilities also important
• Isolated geographical areas of concern
• Islands

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Species Most Vulnerable to Extinction

• Species with a very narrow geographical range
• Species with only one or a few populations
• Species in which population size is small
• Species in which population size is declining
• Species with low population density
• Species that need a large home range
• Animal species with a large body size
• Species that are not effective dispersers
• Seasonal migrants

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Species Most Vulnerable to Extinction

• Species with little genetic variability
• Species with specialized niche requirements
• Species that are characteristically found in
  stable, pristine environments
• Species that are characteristically found in
  stable, pristine environments
• Species that form permanent or temporary
  aggregations
• Species that have evolved in isolation have not
  had prior contact with people
• Species that are hunted or harvested by people
• Species that have closely related species that
  are recently extinct or are threatened with
  extinction

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Box 14 Black Footed Ferret

• List the various threats the ferret has faced.

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Conservation Categories of IUCNInternational
Union Conservation of Nature

• Extinct
• Extinct in the Wild
• Critically Endangered
• Endangered
• Vulnerable
• Conservation-dependent
• Near Threatened
• Least Concern
• Data Deficient
• Not Evaluated

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Conservation Categories of IUCNInternational
Union Conservation of Nature

• Critically endangered species
• gt50 probability of extinction within 10 years or
  3 generations
• Endangered species
• gt20 probability of extinction within 20 years or
  5 generations
• Vulnerable species
• gt10 probability of extinction within 100 years

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Conservation Categories of IUCNInternational
Union Conservation of Nature

• Assignment of categories depends on having at
  least one of the following types of information
• Observable decline in numbers of individuals
• Geographical area occupied by species and number
  of populations
• Total number of individuals alive and number of
  breeding individuals
• Expected decline in numbers of individuals if
  current and projected trends in population
  decline or habitat destruction continue
• Probability of species going extinct in a certain
  number of years or generations

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Natural Heritage Data Centers

• Similar to IUCN
• Covers United States, Canada, 14 Latin American
  countries
• Supported by Nature Conservancy and others
• Given status ranks based on standard critera
• Number of remaining populations
• Number of individuals remaining
• Aerial extent for communities
• Number of protected sites
• Degree of threat
• Innate vulnerability
• Assigned imperilment rank from 1-5
• Critically imperiled to secure
• Blobal, national, regional basis
• Applied to ecological communities!!!

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Summary

• Rare species more prone to extinction than common
  ones.
• Characteristics of vulnerable speciesl
• IUCN 10 conservation categories.
• Nature Conservancy Natural Heritage ecosystem
  categories

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Habitat Destruction, Fragmentation, Degradation,
Global Climate Change

• Chapter 9

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Human Induced Causes of Extinction

• Habitat destruction
• Habitat fragmentation
• Habitat degradation
• pollution, etc.
• Global climate change
• Overexploitation
• Exotic species
• Increased spread of disease

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Human Dominant Ecosystem

• Land Surface
• land use
• demand for resources
• transformed 50 land
• Nitrogen Cycle
• nitrogen fertilizers and burning fossil fuels
  adds nitrogen
• Atmospheric Carbon Cycle
• fossil fuels doubled carbon dioxide levels

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Unequal Use

• US citizen use compared to India use
• 43 times more peterolum
• 34 times more aluminum
• 386 times more paper

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Causes of Extinction

• Rise of Industrial Capitalism
• Materialistic Society
• Inefficient Unequal Use of Resources
• 20 people use 80 resources

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Major groups targeted by trade

• Primates
• Birds
• Reptiles
• Ornamental fish
• Reef corals
• Orchids
• Cacti

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Causes of ExtinctionHuman Induced

• Habitat destruction
• Habitat fragmentation
• Habitat degradation
• Overexploitation
• Exotic Species
• Increased Spread of Disease

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Causes of Extinction

• Population Impact
• 1 billion 1850
• 2 billion 1930
• 5.9 billion 1995
• 6.2 billion 2002
• Use of natural resources
• Agriculture and urbanization

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Problem of Human Population Growth

• Ecological footprint
• Modern city
• 200 times its area
• Affluent overconsume!
• Reevaluate lifestyles

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Population

• Impact of Population
• 1 billion 1850
• 2 billion 1930
• 6 billion 1998
• Decreased mortality
• Longer life spans
• Medical discovery
• Food supply

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Population

• Industrial capitalism
• Materialistic modern societies
• Accelerated demand for natural resources
• Inefficient and unequal use of resources
• Agriculture
• Urbanization

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Habitat Destruction

• Primary cause of loss of diversity is habitat
  destruction that results from expansion of human
  populations and human activities
• Most important way to protect biological
  diversity is to protect habitat

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Habitat Destruction

• Habitat loss major threat
• includes degredation
• Threatened rain forests
• Contain 7 Earths land surface
• Contain 50 Earths species
• Prime Examples
• Madagascar
• Atlantic Coast of Brazil
• Coastal Ecuador

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Threatened Rain Forests

• Synonymous with loss of species
• 7 Earths land surface
• 50 species
• Demand of industrialized countries for cheap ag
  products
• Rubber
• Palm oil
• Cocoa
• Beef
• Wood products

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• Other Threatened Habitats
• Tropical decidious forests
• human density 5 times greater
• Wetlands and aquatic habitats
• critical habitats
• flood control
• drinking water
• power production
• 1990 no net loss
• 1980 swampbuster

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• Other Threatened Habitats
• Mangroves
• Brackish water
• breeding grounds
• nursery habitat
• Grasslands (Prairies)
• easy to convert to ag or urban
• Coral Reefs
• contain 1/3 ocean fish species
• 10 destroyed

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Desertification

• Degrading biological communities in seasonally
  dry climates into man-made deserts
• Tropical grasslands
• Scrub
• Decisuous forests
• Temperate shrublands
• California
• 47 worlds land area fall in this category
• Home to 1 billion people

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• Desertification
• Degredation into artificial deserts
• by human activities
• Process
• Repeated cultivation or overgrazing
• leads to soil erosion and
• loss of soils water holding capacity
• Result
• loss of native species
• loss of soil cover

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Habitat Fragmentation

• Process whereby a large continuous area of
  habitat is both reduced in area and divided into
  two or more fragments
• Patchwork of habitat fragments left behind
• Fragments isolated from one another by highly
  modified or degraded landscape
• Edges experience altered set of conditions edge
  effect
• Fragments usually on least desirable land
• Steep slopes
• Poor soils
• Inaccessible areas

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Habitat Fragmentation

• Habitat is divided or reduced in area
• roads and railroads
• towns
• fields
• Island model of biogeography
• Important differences from islands
• Edge effects
• habitat adjacent to human activities
• center of each habitat closer to an edge
• Example 9.10 page 233
• reduces habitat by 50

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Habitat Fragmentation

• Results
• Reduction of area of original habitat
• Greater amount of edge habitat for given area
• Reduced distance to nearest edge
• Fragment isolation
• Following fragmentation
• Tendency for displaced animals to congregate in
  remaining habitat fragments
• Leads to temporary increase in species numbers
• Then gradual decline

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Effects of Fragmentation on Species Mobility

• Threatens species persistence by creating
  barriers
• Dispersal
• Colonization
• Many species cannot recolonize fragments
• Migration
• Species become extinct within fragments
• Restricted access to food and mates
• Reduces foraging ability of native animals
• Division of populations
• Precipitate population decline and extinction by
  developing subpopulations
• Genetic drift, inbreeding, depression, etc.

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Fragmentation

• Begin with 1000 m segment each side
• Edge is 100 m
• Interior is 64 ha
• Bisect with 2 roads
• Leaves interior of 4 segments
• 8.7 ha each

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Edge Effects

• Microclimate changes
• Light
• Temperature
• Wind
• Humidity
• Increased Incidence of Fire
• Interspecies Interaction
• Potential for Disease

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• Edge Effects
• Microclimate
• Sunlight is absorbed and reflected by leaf layers
  /forest
• gt1 suns energy reaches forest floor sometimes
• Up to 60-300 meters
• Lower temperatures
• Shade tolerant species
• wildflowers
• late-successional species
• Tropical forest
• Humidity sensitive species
• Higher humidity
• Amphibians
• Decreased wind
• Wind velocity reduced by tree canopies

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Edge Effects

• Increased Incidence of Fire
• Increased wind
• Lower humidity
• Higher temperatures
• Exotic species easier to burn
• Established due to edge effect
• Activities occurring near edges
• Agricultural
• Human activities roads

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Edge Effects

• Interspecies Interaction
• Increase vulnerability to invasion by exotic
  species
• And native pest species
• High energy, high nutrient, disturbed enviornment
• Ragweed example
• Then disperse into interior of forest
• Raccoons, skunks, blue jays
• Combination responsible for decline of many
  migratory songbird species

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Edge Effects

• Potential for Disease
• wild populations in contact with domesticated
  species
• No immumity
• Wild species contact domestic species and humans
• Potential for emerging diseases as well
• Lyme disease
• Hanta virus

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Habitat Degradation Pollution

• Habitat can be profoundly affected by our
  activities
• Biological communities can be damaged by external
  factors
• Coral reefs damaged by divers flippers or boat
  anchors
• Cattle in grassland communities or forests
• Fishing trawlers dragging ocean floor
• Pollution from pesticides, sewage, fertilizers,
  nutrients
• Air, water, soil

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Habitat Degradation Pollution

• Pesticide pollution
• Silent Spring, Rachel Carson, 1962
• Biomagnifications (DDT)
• Concentration as you go up the food chain

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Habitat Degradation Pollution

• Water Pollution
• Cultural eutrophication
• Caused by nutrient loads fertilizer, sewage
• Algal blooms thicken and die
• Decompose and absorb all oxygen in water
• Dead Zones
• Sedimentation
• Air pollution
• Acid rain
• Ozone production and nitrogen deposition
• Toxic metals
• Leaded gas
• Developing countries still use
• Forest diebacks

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Habitat Degradation Pollution

• Global Climate Change
• Greenhouse gases
• Carbon dioxide, methane, etc.
• Greenhouse effect
• Global warming
• Global climate change
• Causes
• burning fossil fuels

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• Table 9.5 Evidence for Global Warming
• Increased incidence of heat waves
• Increased incidence of droughts and fires
• Melting of glaciers and polar ice
• Rising sea levels
• Spread of disease to higher elevations
• Earlier spring arrival
• Shifts in species ranges
• Population declines of various species

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Changes in Temperate Tropical Climates

• 10 plant species in U.S. will not be able to
  migrate northward and shift toward poles
• Alpine plants found higher on mountains
• Migrating birds observed spending longer times at
  summer breeding grounds
• Plant species will have to migrate 100-530 km
  north
• 1000-5300 m/year
• 1.4 5.8 degree C change
• Spruce/fir and aspen/birch communities will
  decline 90
• Temperature and rainfall less drastic in tropics
• Small changes have big impact on species
  composition
• Cycles of plant reproduction
• Fire regime
• Migratory birds
• Hurricanes more severe and frequent in tropics

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Plants Climate Change

• Adaptable plant species
• Utilize increased carbon dioxide levels
• Higher temperatures
• Increase growth rates
• Currently seeing increase in plant growh over
  areas of northern high latitudes using satellite
  data
• Shifts in herbivorous insect species
• Plant species flower weeks earlier in growing
  season
• Disrupt pollination systems with specialist
  pollinators
• Ag crops may need to be moved

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Rising Sea Levels

• Mountain glaciers melting
• Polar ice caps shrinking
• Sea levels predicted to rise 9-88 cm
• Destroy or alter 25-80 coastal wetlands of
  United States
• Mangroves affected
• Bangladesh under water
• Sea levels already risen 10-20 cm last 100 years
• Low islands now below water level
• Coral reefs unable to keep pace
• Also threatened with rising water temperatures

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Overall Effect of Global Warming

• Radically restructure biological communities
• Change range of many species
• Pace overwhelm natural dispersal abilities
• Protect sites with large elevational gradients
• New conservation areas
• Protect migration routes
• Corridors
• North-sourth river valleys
• Immediate priority
• Preserve intact communities
• Restoring degraded ones

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Summary

• Disturbances drive species to point of extinction
  as our population grows.
• Major threat to diversity is habitat loss.
• Habitat fragmentation
• Environmental pollution
• Global climate change

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Overexploitation, Invasive Species, Disease

• Chapter 10

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Threats to Biological Communities

• Overexploitation of species
• Invasive species introduction
• Disease transmission

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Overexploitation

• Currently threatens
• 25 endangered vertebrates
• 50 endangered mammals
• Hunting and Harvesting
• Increased efficiency of harvest methods
• mechanization
• Technology (GIS satellites)
• Increased harvest amounts as population increased
• Exceeding sustainable harvest limits

70
Exploitation in the Modern World

• Lack of restraint applies to both ends of
  economic scale
• Bushmeat crisis
• Decline in animal population caused by intensive
  hunting of animals leaving empty forest (Africa)
• Illegal or legal trade
• Restrict firearms and ammunition
• Close roads
• Provide alternative protein sources
• Find examples of this.

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Maximum Sustainable Yield

• Maximum sustainable yield
• Greatest amount of a resources that can be
  harvested each year and replaced through
  population growth without detriment to the
  population
• Equation p. 273
• r is production which can double each year until
  carrying capacity is reached
• B is biomass which can be harvested each year
• Y max rb/4

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What Can Be Done to Stop Overexploitation?

• As rarity increases, it will no longer be
  commercially viable to harvest them
• Sometimes rarity increases demand
• Numbers cannot recover
• CITIES
• Convention on International Trade in Endangered
  Species

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Invasive Species

• Exotic species
• species occurring outside of natural range
• due to human activity
• Geographic barriers once effective
• Human transport bridged that barrier
• Species introductions by
• European colonization
• Horticulture and agriculture
• Accidental transport
• Biological control
• Better competitors no natural predators
• Examples
• Fire ants
• Gypsy moths

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Invasive Species on Islands

• Islands have unique assemblage of endemic species
• Yet particularly vulnerable to depredations by
  invading species
• Exotic species on Islands
• Santa Catalina
• Goats and mammals grazed 48 native plants to
  extinction
• Pacific Islands
• Brown tree snack eats eggs, nestlings, and adult
  birds

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Invasive Species in Aquatic Habitats

• Exotic species in aquatic habitats
• Some purposeful for fisheries
• Sport fishing
• Most unintentional
• Canal building
• Ballast water
• Competitive
• Larger
• More aggressive
• Zebra mussel
• Purple loosestrife
• Lake Victoria

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Ability of Species to Become Invasive

• Exotic Species Have the Edge
• Ability to invade and dominate new habitats
• Especially degraded habitats altered by humans
• Fire
• Increased nutrient levels
• Enhanced light availability
• Most serious threat to National Park System
• Absence of natural predators, pests, diseases in
  new habitat
• No effective checks on their numbers
• Better to adapting to human impacts
• Most serious threat to national parks
• Numbers increase at expense of native species
• Better competitors
• Well established populations may be impossible to
  remove from communities
• May hybridize with close relatives, eliminating
  genotypes/species
• Iowa Ecotype Project

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Increased Transmission of Disease

• Disease carrying vectors as a result of human
  activities
• Interaction with humans and wild animals
• Infection by disease organisms
• Micro parasites
• Viruses, bacteria, fungi, protozoa
• Macro parasites
• Helminth worms, parasitic arthropods
• Epidemiology
• Dense populations promote high transmission rates
• Indirect habitat destruction effects can increase
  disease susceptibility
• Species contact other species previously never
  close

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Implications of Invasive Species Diseases for
Human Health

• Displace native species
• Serious injuries to humans
• Fire ants
• Killer bees
• Serious pests and diseases
• Giardia lamblia in beavers and elk
• Requires water to be purified before drinking
• Lyme disease
• West Nile virus
• Cholera
• Disenchantment with outdoor experience
• Could lose conservation funding

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Conclusion

• Overexploitation caused many species to decline
• Degradation, such as pollution, caused same
• Threats to biological diversity underlying cause
  human activities
• Increasing population

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Do one thing that scares you every day.

• Eleanor Roosevelt

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Summary

• Overexploitation a major threat to worlds
  species.
• Invasive species especially a problem on islands
  and in aquatic communities.
• Disease in wild species increased by human
  activities.
• Species at risk by a combination of factors.