Introduction to Species Ecology

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Introduction to Species Ecology

• Environmental Studies
• October 2005

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What is a species and how many are there?

• A species is a group of organisms that resemble
  one another in appearance, behavior, chemistry,
  and genetic make-up
• The true test to determine if two individuals are
  members of the same species is to see whether or
  not viable (fertile) offspring can be produced
  under natural conditions
• We dont know how many exist on earth
• 1.5 to 1.8 million identified
• Estimates (save bacteria) are 3 to 100 million
• Most common are insects and plants

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Special Categories of Species

• Native vs. Non-native (aka exotic, alien)
• See figure 8-7 pg 171
• Indicator Species
• Serve as early warnings of damage to a community
  or ecosystem
• Respond quickly to environmental change
• Songbirds, amphibians, rainbow trout, coral reefs
• Keystone Species
• Role or niche in an ecosystem is much more
  important than their abundance would suggest
• Bees, ants, bats, hummingbirds (pollinators)
• Wolf, leopard, lion, sea otter, white shark (top
  predator)

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Characteristics of Successful Invasive Species
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Generalist vs. Specialist Species

• Niche role in the biological community
• Includes
• range of tolerance to abiotic factors
• Types and amounts of resources it uses
• Interactions with other species
• Habitat physical location address
• Generalist species (broad niche)
• Can live in variety of habitats, eat a variety of
  things, tolerate a wide array of conditions
• Flies, cockroaches, deer, raccoons, humans
• Specialist species (narrow niche)
• Can live in only one or a few habitats, narrow
  diet, tolerate a narrow range of conditions
• More vulnerable to extinction (giant panda)

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Biotic interactions between species

• Inter vs. Intraspecific competition
• Interbetween species
• Intrawithin species
• Strategies to avoid competitionresource
  partitioning (eg warblers)
• Predation
• Why is predation important?
• Parasitism
• Parasite usually smaller, gradually weakens host
  over time, rarely kills its host
• Mutualism (symbiosis)
• Commensalism
• Epiphytic plants (eg. Orchids)

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Resource Partitioning in Warblers
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Mutualism/Symbiosis
Coral Reef is another great example
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Commensalism
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What is biodiversity

• A renewable resource
• The different forms of life and life sustaining
  processes that can best survive the variety of
  habitats on earth
• Four different types fall under biodiversity
• Genetic Diversity
• Species Diversity
• Ecological Diversity
• Functional Diversity

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Why is biodiversity worth saving?

• Economically important
• 40 of all medicines and 80 of top 150
  prescription drugs in USA derived from living
  organisms
• Give us wood, fibers, energy, raw materials,
  industrial chemicals, medicines etc that fuel our
  economies (estimated _at_ 37 trillion/yr)
• Crops domesticated from wild plants
• Need genetic diversity to develop future crops
• Recreation and tourism
• Ethical and moral considerations
• Natural Capital and its Life Sustaining Processes
• Purify our water, air, soil
• Decompose our organic and chemical wastes
  recycle nutrients
• Natural pest control and pollination
• Regulate climate, protect us from harmful
  radiation
• Production of all food
• Prevent soil erosion/flood control
• Detoxification of human and industrial wastes

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Who cares!? Its just one species!

• Every species today contains genetic information
  that represents millions of years of evolution
  and adaptation to earths changing environmental
  conditions
• This diversity also represents the raw materials
  for future adaptations if environmental
  conditions change
• In other words, biodiversity is lifes insurance
  policy against natural disaster!
• Loss of biodiversity
• Reduces the availability of ecosystem services
• Decreases ability of species and ecosystems to
  adapt to changing environmental conditions

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BiodiversitySpeciation minus extinction

• Speciation formation of new species
• Extinction total disappearance of a spp.
• When environmental conditions change, a species
  must either
• Move to a more favorable environment OR
• Adapt to the new conditions OR
• Die (become extinct)

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Status of Biodiversity 1998-2018
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Types of Extinctions

• Local
• No longer in an area it once inhabited
• Ecological
• So few left that it cant do its job
• Biological
• No longer found anywhere on earth
• Mass
• Huge amounts of species lost over a short period
  of time
• Much faster than the background rate

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Human Impacts on Extinction Rates

• Before humans, estimated rate was one species per
  million ( 0.0001 per yr)
• Now, best guess is 0.1 per yr (1000X background
  rate)
• If the rate is as high as 1 as some believe
  (E.O. Wilson), then 20 of current animal and
  plant species could be gone by 2030 and 50 gone
  by the end of this century
• At this rate, it will take at least 5 million
  years for speciation to rebuild the diversity we
  destroy during this century.

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Extinctions over time
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Extinctions over time II
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Are humans currently causing a mass extinction?

• During 20th century, it has been estimated that
  the extinction rate has increased 100 to 1000
  times the natural background rate
• We already use 27 of earths NPP
• 75 of habitable area disturbed
• World wide forest cover reduced by 20-50
• More than half of wetlands of the world
  threatened
• On our time scale, the loss of these species
  cannot be recouped by formation of new species
  (b/c this takes a long time)

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Premature Extinctions Caused By Human Beings
Nature Conservancy Study 539 extinctions since
1600
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Endangered vs. Threatened

• Endangered
• So few left that species could soon become
  extinct over all or most of its range
• Threatened
• Still relatively abundant but b/c of declining
  numbers is likely to become endangered in the
  near future
• WWF study 30k Under threat of extinction
• 34 of worlds fish
• 25 of worlds amphibians
• 24 of worlds mammals
• 20 of worlds reptiles
• 14 of worlds plant species
• 12 of worlds bird species

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Endangered and Threatened Part I
Florida manatee
Northern spotted owl (threatened)
Florida panther
Bannerman's turaco (Africa)
Gray wolf
Devil's Hole pupfish
Snow leopard (Central Asia)
Black footed ferret
Symphonia (Madagascar)
Utah prairie dog (threatened)
Ghost bat (Australia)
Black rhinoceros (Africa)
Oahu tree snail
California condor
Black lace cactus
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Endangered and Threatened Part II
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Endangered and Threatened Part III
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What makes a species vulnerable to extinction?

• Specialized niche
• Low reproductive rate
• Blue whales, giant panda, rhinoceros
• Feeds at high trophic level
• Bengal tiger, bald eagle
• Fixed migratory patterns
• Blue whale, whooping crane, sea turtles
• Commercially valuable
• Snow leopard, tigers, elephants, rare birds,
  orchids
• Need Large Territory
• Condor, Florida panther

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Underlying Causes of Extinction
1Habitat loss
Habitat degradation
Overfishing
2Introducing nonnative species
Basic Causes
Climate change

• Population growth
• Rising resource use
• Improper accounting
• Poverty

Commercial hunting and poaching
Pollution
Sale of exotic pets and decorative plants
Predator and pest control
Fig. 8-5, p 169
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Poaching often Extinction
CITIES Treaty
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Hot Spots of Biodiversity in the USA
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Habitat Loss
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Human Impacts on Ecosystems

• Fragmenting and degrading habitat
• e.g. Tropical forests being cut at a rate of 0.6
  to 2 per year
• Half of remaining forests lost or degraded in 25
  to 83yrs
• Eliminating some key predators
• Deliberately or accidentally introducing exotic
  species
• Over harvesting of renewable resources
• Interfering with normal cycling and flows of
  energy in ecosystems

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Preserving Biodiversity
PRESERVE HOT SPOTS