Introduction to Species Ecology

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Introduction to Species Ecology

• Environmental Studies
• October 2004

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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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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 important?

• The rich variety of genes, species, biological
  communities, and life sustaining processes
• Give us wood, fibers, energy, raw materials,
  industrial chemicals, medicines etc that fuel our
  economies (estimated _at_ 37 trillion/yr)
• 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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Evolution 101 Revisited

• Recall some basic evolution
• Microevolutionchange in gene pool of a
  POPULATION over time in response to natural
  selection
• Adaptations are inherited traits that increase
  the chance of survival ( ability to pass on
  genes)
• Fitnesshow many offspring are produced per
  individual
• Depends upon genetic variability in a pop
• Sexual reproduction
• Mutations (random, unpredictable, ultimate source
  of new variation, rare events)
• Sequence?genes mutate, individuals are selected,
  and populations evolve
• Over time, accumulated changes can lead to a new
  speciesspeciation

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Allopatric Speciation (Macroevolution)

• Two phases (stop)
• Geographic isolation
• Members of same species become physically
  separated for long periods of time
• Physical barrier, physical change (volcanic
  eruption, earthquake), or carried by wind/water
• Reproductive isolation
• Mutation and natural selection change the gene
  pools of geographically isolated populations
• Members of isolated populations over time may
  become so different in genetic make up that they
  can no longer interbreed or produce viable
  (fertile) offspring
• Can take hundreds of years in organisms with
  really short life spans (bacteria) and thousands
  to millions of years for most other species
• Animation

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Allopatric Speciation Example
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BiodiversitySpeciation minus extinction

• When environmental conditions change, a species
  must either
• Evolve (become better adapted) OR
• Move to a more favorable environment OR
• Cease to exist (become extinct)
• Extinction is the ultimate fate of all species
  just as death is ultimate fate of all individuals
• 99.9 of all of the species that have ever
  existed are now extinct!
• Background Rate vs. Mass Extinctions

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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)
• Genetic engineering wont solve this (why?)

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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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Premature Extinctions Caused By Human Beings
Nature Conservancy Study 539 extinctions since
1600
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Poaching often Extinction
CITIES Treaty
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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
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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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Characteristics of Species Prone to Extinction
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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

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Status of Biodiversity
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Why preserve wild species?

• Economic goods
• Food, fuel, lumber, fiber, paper, etc
• 40 of all medicines and 80 of top 150
  prescription drugs in USA derived from living
  organisms
• Crops domesticated from wild plants
• Need genetic diversity to develop future crops
• Ecological services
• Genetic information
• Recreation
• Eco-tourism
• 1 male lion living to age 7550K or 1000 if
  killed by a poacher for its skin
• Ethical considerations

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Underlying Causes of Extinction
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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
• Simplifying natural ecosystems
• Creating monocultures
• Using, wasting, or destroying an increasing
  percentage of earths NPP (27 of total)
• Strengthening some populations of pest species
  and disease causing bacteria by causing genetic
  resistance through overuse of pesticides
  antibiotics
• 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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Destruction of Tropical Forests
Fig. 7-11, p. 148
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Lessons from Nature

• Our lives, lifestyles, and economies are totally
  dependent upon the sun and the earth
• We need the earth, it does not need us
• Everything is connected to everything else
• We can never do merely one thing
• We should reduce and minimize the damage we do to
  nature
• We should use care, restraint, humility, and
  cooperation with nature as we alter the biosphere
  to meet our needs and wants
• Precautionary Principle
• Take precautionary measures to prevent harm even
  if some of the cause and effect relationships
  have not been fully established scientifically.

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Sustainability Lessons From Nature

• Ecosystems use renewable solar energy as their
  primary source of high quality nrg
• We should be powered by current sun not ancient
  sun stored as polluting fossil fuels
• Ecosystems replenish nutrients and dispose of
  wastes by recycling chemicals
• We should prevent and reduce matter and energy
  waste
• Biodiversity helps maintain the integrity and
  functioning of ecosystems
• We should prevent whenever possible the premature
  extinction of species by protecting key habitats
• There are always limits to pop growth and
  resource consumption
• We should slow pop growth and consumption

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Preserving Biodiversity
PRESERVE HOT SPOTS
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Hot Spots of Biodiversity in the USA
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Other 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