Community Ecology, Population Ecology, and Sustainability

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Community Ecology, Population Ecology, and
Sustainability

• Chapter 6

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Question 1Describe the three characteristics
that describe biological community structure. Are
complex communities more sustainable than simple
ones?
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3 Characteristics

• Physical (Community) Structure
• shape, size stratification distribution of
  populations species in a community
• Species Diversity
• number of different species an area contains
  (richness) how many of each type of species
  there is (eveness)
• Niche Structure
• how many ecological niches occur, how they
  resemble or differ from one another how various
  species interact

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Is Complexity more Sustainable?

• Having many species can provide some stability
  for communities
• However we do not know if this applies to all
  communities
• More research is needed in this field!

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Question 2Distinguish among the following
roles played by species and give two examples of
each. Explain the important effects these
organisms have on their communities.
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Types of Species

• Native
• Nonnative (invasive or alien)
• Indicator
• Keystone
• Foundation

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Native Species

• Species that normally live thrive in a
  particular community

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Non-Native (Invasive) Species

• Species that migrate into or are deliberately or
  accidentally introduced into a community
• Includes
• domesticated crops
• animals
• Can crowd out native
• species cause
• unintended unexpected
• consequences

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Georgias Invasive Species
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Indicator Species

• Provide early warnings of damage
• Trout - indicator of water quality
• Birds found everywhere affected quickly
• Butterflies association w/ plants makes them
  vulnerable
• Amphibians water/land life cycle skin eggs
  absorbs pollutants UV radiation easily

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Life Cycle of a Frog
Young frog
Adult frog (3 years)
sperm
Tadpole develops into frog
Sexual reproduction
Tadpole
Eggs
Fertilized egg development
Egg hatches
Organ formation
Fig. 6-3, p. 112
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Keystone Species

• Keystone species play critical ecological roles
• Pollination
• Top predators
• Dung beetles
• Sharks

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Why Should We Care about the American Alligator?

• Keystone species
• Create Gator Holes which hold water
• create refuge
• Nesting mounds provide feeding sites
• for birds
• Eat gar a predatory species of
• game fish
• Keep open water free of vegetation

Fig. 6-1, p. 108
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Foundation Species

• Similar to keystones species
• Play important roles in shaping communities by
  creating enhancing their habitats in ways that
  benefit other species.
• Elephants
• Contributions of
• bats and birds

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Question 3Distinguish among the species
interactions. Describe how predators increase
their chances of success how prey species
defend themselves.
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Species Interactions

• Interspecific Competition
• Resource Partitioning
• Predation

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Resource Partitioning and Niche Specialization

• Some species (over a long time) develop
  adaptations to reduce or avoid competition.
• Through natural selection, broad/overlapping
  niches of 2 competing species can become more
  specialized so limited resources are shared.
• Example Hawks owls eat similar prey but one
  hunts in day and other by night

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Resource Partitioning and Niche Specialization
Number of individuals
Species 1
Species 2
Region of niche overlap
Resource use
Number of individuals
Species 1
Species 2
Resource use
Fig. 6-4, p. 114
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Resource Partitioning of Warbler Species
Fig. 6-5, p. 115
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How Do Predators Increase Their Chances of
Getting a Meal?

• Pursuit (Speed)
• Senses
• Camouflage and ambush
• Chemical warfare (venom)

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Avoiding and Defending Against Predators

• Escape
• Senses
• Armor
• Camouflage

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Avoiding and Defending Against Predators

• Chemical warfare
• Warning coloration
• Mimicry
• Behavior strategies
• Safety in numbers

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How Species Avoid Predators
Fig. 6-6, p. 116
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Mimic Octopus Coconut Octopus

• http//www.youtube.com/watch?vH8oQBYw6xxc
• http//www.youtube.com/watch?v1DoWdHOtlrk
• http//www.msnbc.msn.com/id/45243390/ns/technology
  _and_science-science/.TrwvOVYknzU

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Question 4 Distinguish among three forms of
symbiotic relationships and give one example of
each.
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Parasitism

• Occurs when one species (parasite) feeds on part
  of another organism (host), usually by living on
  or in host.

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Mutualism

• Both species benefit
• Benefits include nutrition and protection
• Gut inhabitant mutualism

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Commensalism

• Species interaction that benefits one and has
  little or no effect on the other
• Epiphytes

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Question 5Define succession. Distinguish
between primary and secondary succession. Compare
the classic view of succession to the modern
view.
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Ecological Succession Communities in Transition

• What is ecological succession?
• Primary succession
• Secondary succession

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Primary Ecological Succession
Lichens and mosses
Exposed rocks
Balsam fir, paper birch, and white spruce climax
community
Jack pine, black spruce, and aspen
Heath mat
Small herbs and shrubs
Time
Fig. 6-9, p. 119
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Secondary Ecological Succession
Mature oak-hickory forest
Young pine forest with developing understory of
oak and hickory trees
Shrubs and pine seedlings
Perennial weeds and grasses
Annual weeds
Time
Fig. 6-10, p. 120
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Classic vs. Modern views of Succession

• Classic View succession is an orderly
• sequence of expected
• events
• Modern View we cannot predict the
• course of succession or
• view it as an ideal
• progress to a climax
• community

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Question 6Define population terms. Write an
equation to mathematically describe the
relationship between these variables and the rate
of population change.
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Population Dynamics Factors Affecting Population
Size

• Population change
• (births immigration) (deaths emigration)

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Question 7Explain why no species can increase
in size indefinitely (forever).
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Limits on Population Growth

• No indefinite population growth b/c resources are
  limited
• Biotic potential
• Environmental resistance
• Carrying capacity (K)
• Biotic Potential Environmental Resistance
  determine K

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Population Growth Curves
Environmentalresistance
Carrying capacity (K)
Population size (N)
Biotic potential
Exponential growth
Time (t)
Fig. 6-11, p. 121
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Question 8Distinguish between exponential
growth (J-shaped) and logistic growth (S-shaped).
Describe what happens if a population overshoots
the carrying capacity.
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Exponential and Logistic Population Growth

• Resource availability controls population growth
• Exponential growth (J-shaped)
• Logistic growth (S-shaped)

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Exponential Growth

• Growth starts slowly, but then accelerates

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Logistic Growth

• Involves exponential population growth followed
  by a steady decrease in population growth w/ time
  until population size levels off

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Logistic Growth of Sheep Population
2.0
Overshoot
Carrying Capacity
1.5
Number of sheep (millions)
1.0
.5
1800
1825
1850
1875
1900
1925
Year
Fig. 6-12, p. 121
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Exponential Growth, Overshoot and Population
Crash of Reindeer
Population Overshoots Carrying Capacity
2,000
Population crashes
1,500
Number of sheep (millions)
1,000
Carrying capacity
500
0
1910
1920
1930
1940
1950
Year
Fig. 6-13, p. 122
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Question 9Distinguish between r-selected
species (opportunists) and K-selected species
(competitors). Where do most organisms
reproductive patterns fall in relation to these
extremes?
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Reproductive Patterns

• r-selected species (opportunists)
• Environmental impacts on opportunists
• K-selected species (competitors)

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r-selected Opportunists and K-selected Species
Fig. 6-15, p. 123
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Reproductive Patterns

• Most organisms fall somewhere in between the
  r-selected K-selected species extremes.

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Question 10 List the eight major ways in
which humans have altered nature to meet our
growing needs that also threaten the survival of
other species and our own.
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Human Impacts

• Reduction of biodiversity
• Increasing use of Earths NPP
• Increasing genetic resistance of pest species and
  disease-causing bacteria
• Elimination of many natural predators

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Human Impacts

• Deliberate or accidental introduction of
  potentially harmful species into communities
• Using some renewable resources faster than they
  can be replenished
• Interfering w/ earths chemical cycling energy
  flow processes
• Relying mostly on polluting fossil fuels

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The Cove

• Using state-of-the-art equipment, a group of
  activists, led by renowned dolphin trainer Ric
  O'Barry, infiltrate a cove near Taijii, Japan to
  expose both a shocking instance of animal abuse
  and a serious threat to human health.

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Blackfish

• "Blackfish" traces the history of killer whales
  in captivity leading up to the 2010 killing of a
  Sea World trainer.