Ecosystem

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Ecosystem

• Ecosystem community (all biotic) physical
  environment (all abiotic)
• Ecology study of interrelationships between
  biotic and abiotic elements in an ecosystem

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Habitat

• Habitat any part of the Earth where a species
  can live, temporarily or permanently
• organisms physical surroundings
• where an organism lives

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Ecological Niche

• Ecological Niche functional role of a species
  in the community, including habitat, activities
  relationships
• what an organism does, its occupation

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Abiotic Factors

• Sunlight
• Water
• Air
• Climate (Temperature, precipitation, wind)
• Soil Rocks
• Periodic disturbances

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Key Properties of Communities

• 1) Diversity variety of different organisms
• 2) Prevalent Form of Vegetation
• 3) Stability ability to resist change
• 4) Trophic Structure

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Species Diversity

• Species diversity often evaluated based on two
  factors
• 1) Species Richness total number of different
  species
• 2) Relative Abundance or Evenness number of
  fairly common or noticeable species

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Species Diversity
Species Richness ? Relative Abundance ?
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Interspecific Interactionsin a Community

• 1) Competition
• 2) Predation
• (predator-prey or herbivore-plant)
• 3) Symbiosis

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Competition

• Interspecific Competition
• VS
• Intraspecific Competition

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Competitive Exclusion Principle

• Competitive Exclusion Principle no two species
  can occupy the same niche at the same time
• two species so similar that they compete for
  the same limiting resources cannot coexist in the
  same place
• - G. F. Gause

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Chthamalus vs Balanustwo species of barnacles
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Intertidal Ecology Foundations of Experimental
Community Ecology
Joseph Connell, 1961
The Pattern Barnacle distributions in rocky
intertidal zones
Mean High Water Spring Tide
Mean High Water Neap Tide
Mean Low Water Neap Tide
Chthalamus stellatus
Balanus balanoides
Mean Low Water Spring Tide
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• Alternative Hypotheses
• Chthamalus distribution is determined by physical
  factors
• Chthamalus distribution is determined by space
  competition with Balanus
• Cthamalus distribution is determined by predation
  by the snail, Thais lapillus

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Three Experimental Manipulations
Rock
(1) Transplanted rocks to regions throughout
intertidal
Settled Chthamalus
Mean High Water Spring Tide
Mean High Water Neap Tide
Mean Low Water Neap Tide
Chthamulus stellatus
Balanus balanoides
Mean Low Water Spring Tide
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Three Experimental Manipulations
Rock
(2) On rocks settled by both species, partitioned
rock in ½ and removed all Balanus from one side.
Settled Chthamalusand Balanus
Mean High Water Spring Tide
Mean High Water Neap Tide
Mean Low Water Neap Tide
Chthamalus stellatus
Balanus balanoides
Mean Low Water Spring Tide
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Three Experimental Manipulations
Snail exclosure
(3) Performed a snail exclosure experiment
Mean High Water Spring Tide
Mean High Water Neap Tide
Mean Low Water Neap Tide
Chthamalus stellatus
Balanus balanoides
Mean Low Water Spring Tide
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Results

• In absence of Balanus, Chthamalus enjoyed high
  survival throughout intertidal zone
• physical factors not important
• Snail exclosure had no affect on Chthamalus
  survival
• snail predation not important
• (3)Balanus removal greatly enhanced Chthamalus
  survival
• competition for space is important

Mean High Water Spring Tide
Mean High Water Neap Tide
Mean Low Water Neap Tide
Chthamalus stellatus
Balanus balanoides
Mean Low Water Spring Tide
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Competitive Exclusion Principle

• Loser must adapt or be eliminated
• One possibility is Resource Partitioning,
• they use the same resource at different
• times, ways, or places
• (at least one difference between the two
  organisms niches)

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Resource Partitioning

• Competitors segregate to avoid competition based
  on
• Size of food
• Type of food
• Habitat usage
• Feeding times

lions hunt large prey, leopards smaller prey
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Resource Partitioning
hawks hunt in daytime, owls at night
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Predation

• Predation consumption of one species prey by
  another predator, also includes herbivores
  eating plants

What are some adaptations that have evolved in
predators and in prey?
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Adaptations

• Predators speed quickness, eyesight,
  camouflage, larger brain, sharp claws teeth,
  stingers, and poisons
• Prey speed quickness, hiding, live in groups,
  porcupine quills , turtle shell, camouflage,
  chemicals (skunk, poisons), distraction displays,
  and mimicry
• Plants spines, thorns, tough leathery leaves,
  protective chemicals (strychnine, morphine,
  nicotine, distasteful)

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Selective Pressures

• Selective pressures are elements of an organisms
  environment that make an adaptation
  advantageous.

Identify the selective pressure for the following
adaptations Long, thick fur Thorns Fangs Camoufla
ge Production of beta lactamase
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Symbiotic Relationships

• Species 1 Species 2
• 1) Parasitism benefits harms
• 2) Mutualism benefits benefits
• 3) Commensalism benefits neutral

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Parasitism

• Parasitism is where the parasite gets nourishment
  from the host, much like predation except host is
  usually not killed immediately.
• Example microbes that infect plants animals
  Plasmodium vivax invades RBC, causing them to
  burst and triggering the chills fever of
  malaria
• Over 100 human parasites are known

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Mutualism

• Examples
• Honey bees get nectar while pollinating flowers
• Rhizobium, N2- fixing bacteria that provide
  nitrogen to plants in return for glucose from the
  plant
• Mycorrhizae fungi living in plant roots that
  increase absorption of nutrients get nutrients
  from the plant

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Mycorrhizae fungi living in plant roots
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Mycorrhizae fungi increase absorption of
nutrients by plants
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Commensalism

• In commensalism the host often provides a home or
  transportation
• For example Remoras attached to sharks

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Commensalism

• Examples of commensalism
• Epiphytes which are plants that grow on plants
• E. coli bacteria that live in human intestine

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Life on a Leaf

• A look at the fungal community that grows on
  healthy new leaves.

Includes examples of a variety of
interrelationships between organisms.
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Fungi
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Fungi

• Heterotrophs
• Digest food externally absorb small nutrient
  molecules
• Most are multicellular (yeast unicellular)
• Form a mycelium, which is a netlike mass of
  filaments called hyphae
• Hyphae grow extend around and through food
  source

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Hyphae grow longer, not thicker WHY?
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Production of antibiotic by Penicillium fungus
What type of relationship?
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Fungi

• Fungi grow FAST mycelium can add up to
  kilometer of hyphae per day
• Hyphae grow through or around plant cells
  (enzymes digest plant cells)
• If fungus grows on dead plant ??
• If fungus grows on live plant ??

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Fungal Reproduction

• Yeast is unicellular and reproduces by dividing
  into two new cells
• Sexual or Asexual?

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Fungal Reproduction

• In multicellular fungi, sometimes two different
  hyphae fuse together (combining their DNA) and
  produce a spore
• Spore develops into new mycelium

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Fungal Life Cycle
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• Mycelium can live a LONG time in the soil.
• In Northern Michigan one mycelium formed from a
  single spore about 1500 years ago covers about 30
  acres
• In Oregon a single mycelium is 3.4 miles in
  diameter, covers 2200 acres, weighs 100s of tons
  and is at least 2400 years old

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Coevolution

• Coevolution is when the adaptations of two
  species are closely connected that is when an
  adaptation in one species leads to a counter
  adaptation in a second species.
• Coevolution is when two species, with a close
  ecological relationship, act as selective
  pressures for each other

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Coevolution

• Adaptation the passionflower vines, Passiflora,
  produce toxic chemicals that protect their
  leaves
• Counter adaptation
• Heliconius butterfly
• caterpillars eat the
• leaves they have
• enzymes that break
• down toxic chemicals

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• Behavioral adaptation by Heliconius females is
  not laying eggs on leaves with bright yellow eggs
  already on them which would reduce
  intraspecific competition

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• Some passionflower vines have sugar secreting
  glands that mimic the eggs,

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Coevolution

• Adaptation Bats use echolocation (beams of
  ultrasonic sound waves, 20-60 kHz, returning
  echoes) to see prey
• Counter adaptation some insects (lacewings,
  praying mantises, most moths) can hear
  high-pitched sound waves

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• Bats in search mode send out clicks at 10 to
  20/sec, gets closer to prey rate increases up
  to several 100/sec just prior to snatching prey
• Bats detect prey over short range 5 to 10 m
• Moths detect clicks 40 m away, and fly away from
  the slow click rate
• If fast click rate detected they take evasive
  maneuvers (power dives, barrel rolls, etc)

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• Counter adaptation tiger moths generate their
  own clicks
• Warns bat of bad tasting prey (avoid after 1st
  taste)
• Startle the bat (bats do get used to it)
• jam the sonar interfere with bats ability to
  pinpoint prey
• Only works if clicks arrive with 1st returning
  echo, so window of opportunity only 1/1,000 sec
• Bats still catch gt50 of prey they attack

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• Counter-counter adaptation tropical gleaning
  bats use ultra high frequency (up to 212 kHz)
  sound waves that are above the insects ability to
  detect
• Counter-counter-counter adaptation moths have
  sensors that detect wind movement created when
  bats hover for an instant prior to striking prey
  gives moth a chance to quickly drop to ground
• Right now bats are developing ???