Community Ecology,
Population Ecology, and
Sustainability
Chapter 5 (New Book – 14th Ed)
(Chapter 6 – Old Book – 13th Ed)
Why Should We Care about the
American Alligator?

Overhunted

Niches

Ecosystem services

Keystone species

Endangered and threatened species

Alligator farms
New pp. 74-75
Key Concepts







Factors determining number of species in
a community
Roles of species
Species interactions
Responses to changes in environmental
conditions
Reproductive patterns
Major impacts from humans
Sustainable living
Community Structure and
Species Diversity

Physical appearance

Edge effects

Species diversity or richness

Species abundance or evenness

Niche structure
Natural Capital: Types, Sizes, and
Stratification of Terrestrial Plants
Tropical
rain forest
Coniferous
forest
Deciduous
forest
Thorn
forest
Thorn
scrub
Tall-grass Short-grass
prairie
prairie
Desert
scrub
OLD Fig. 6-2, p. 110
Species Diversity and Ecological
Stability

Many different species provide ecological stability

Some exceptions

Minimum threshold of species diversity

Many unknowns

Net primary productivity (NPP)

Essential and nonessential species
Types of Species

Native

Nonnative (invasive or alien)

Indicator

Keystone

Foundation
Indicator Species

Provide early warnings

Indicator of water quality

Birds as environmental indicators

Butterflies

Amphibians
New p. 73
Amphibians as Indicator Species

Environmentally sensitive life cycle

Vulnerable eggs and skin

Declining populations
New p. 73
Life Cycle of a Frog
Young frog
Adult frog
(3 years)
sperm
Tadpole develops into
frog
Sexual
reproduction
Eggs
Fertilized egg
development Organ formation
Tadpole
Egg hatches
OLD Fig. 6-3, p. 112
Possible Causes of Declining
Amphibian Populations

Habitat loss and fragmentation

Prolonged drought

Pollution

Increases in ultraviolet radiation

Parasites

Overhunting

Disease

Nonnative species
Why Should We Care about
Vanishing Amphibians?

Indicator of environmental health

Important ecological roles of amphibians

Genetic storehouse for pharmaceuticals
Keystone Species

What is a keystone?

Keystone species play critical ecological roles

Pollination

Top predators

Dung beetles

Sharks
New p. 74
Why are Sharks Important?

Ecological roles of sharks

Shark misconceptions

Human deaths and injuries

Lightning is more dangerous than sharks

Shark hunting and shark fins

Mercury contamination

Medical research

Declining populations

Hunting bans: effective?
New p. 61
Foundation Species

Relationship to keystones species

Play important roles in shaping communities

Elephants

Contributions of bats and birds
Species Interactions

Interspecific competition

Predation

Parasitism

Mutualism

Commensalism
Number of individuals
Resource Partitioning and Niche
Specialization
Species 1
Species 2
Region
of
niche overlap
Number of individuals
Resource use
Species 1
Species 2
OLD
Resource use
Fig. 6-4, p. 114
Resource Partitioning of Warbler
Species
New Fig. 5-2, p. 81
OLD Fig. 6-5, p. 115
Predator and Prey Interactions

Carnivores and herbivores

Predators

Prey

Natural selection and prey populations
New pp. 81-83
How Do Predators Increase Their
Chances of Getting a Meal?

Speed

Senses

Camouflage and ambush

Chemical warfare (venom)
New pp. 81-83
Avoiding and Defending Against
Predators









Escape
Senses
Armor
Camouflage
Chemical warfare
Warning coloration
Mimicry
Behavior strategies
Safety in numbers
New pp. 81-83
How Species Avoid Predators
Span worm
Wandering leaf insect
Poison dart frog
Viceroy butterfly mimics
monarch butterfly
Bombardier beetle
Hind wings of io moth
resemble eyes of a
much larger animal
Foul-tasting monarch
butterfly
When touched, the
snake caterpillar
changes shape to look
like the head of a snake
New Fig. 5-3, p. 82 OLDFig. 6-6, p. 116
Parasites

Parasitism

Hosts

Inside or outside of hosts

Harmful effects on hosts

Important ecological roles of parasites
New pp. 83-84
Mutualism

Both species benefit

Pollination

Benefits include nutrition and protection

Mycorrhizae

Gut inhabitant mutualism
New p. 84
Examples of Mutualism
Oxpeckers and black rhinoceros
Clown fish and sea anemone
New Fig.
5-5. p. 84
Mycorrhizae fungi on juniper
seedlings in normal soil
© 2006 Brooks/Cole - Thomson
Lack of mycorrhizae fungi on
juniper seedlings in sterilized soil
OLD
Fig. 6-7, p. 117
Commensalism

Species interaction that benefits one
and has little or no effect on the other

Example: Small plants growing in
shade of larger plants

Epiphytes
New pp. 84-85
Bromeliad Commensalism
New Fig. 5-6, p. 85
OLD
Fig. 6-8, p. 118
Ecological Succession:
Communities in Transition

What is ecological succession?

Primary succession

Secondary succession
New pp. 88-89
Primary Ecological Succession
New
Lichens
Exposed
and mosses
rocks
Small herbs
and shrubs
Heath mat
Jack pine,
black spruce,
and aspen
Balsam fir, paper
birch, and white
spruce climax
community
New
Ne
New Fig.5-9,p.89 OLD Fig. 6-9, p.
NewNewwmmmmmmm
Secondary Ecological Succession
Annual
weeds
Perennial
weeds and
grasses
Shrubs
and pine
seedlings
Young pine forest with
developing understory
of oak and hickory
trees
Mature oak-hickory forest
New Fig.5-10,p.90 OLD Fig. 6-10, p.
How Predictable is Succession?

Climax community concept

“Balance of nature”

New views of equilibrium in nature

Unpredictable succession

Natural struggles
New pp. 88-89
Population Dynamics: Factors
Affecting Population Size

Population change = (births + immigration)
– (deaths + emigration)

Age structure (stages)

Age and population stability
New p. 85
Limits on Population Growth

Biotic potential

Intrinsic rate of increase (r)

No indefinite population growth

Environmental resistance

Carrying capacity (K)
New pp. 86-87
Exponential and Logistic
Population Growth

Resources control population growth

Exponential growth

Logistic growth
New pp. 86-87
Population Growth Curves
Population size (N)
Environmental
resistance
Carrying capacity (K)
Biotic
potential
Exponential
growth
Time (t)
New Fig. 5-7, p. 86
OLD Fig. 6-11, p. 121
Logistic Growth of Sheep Population
Number of sheep (millions)
2.0
Overshoot
Carrying Capacity
1.5
1.0
.5
1800
1825
1850
1875
1900
1925
Year
OLD Fig. 6-12, p. 121
When Population Size Exceeds
Carrying Capacity

Switch to new resources, move or die

Overshoots

Reproductive time lag

Population dieback or crash

Famines among humans

Factors controlling human carrying capacity
New pp. 87-88
Number of sheep (millions)
Exponential Growth, Overshoot and
Population Crash of Reindeer
Population
Overshoots
Carrying
Capacity
2,000
Population
crashes
1,500
1,000
500
Carrying
capacity
0
1910
1920
1930
1940
1950
Year
New Fig. 5-8, p. 87
OLD Fig. 6-13, p. 122
Reproductive Patterns

r-selected species

Opportunists (mostly r-selected)

Environmental impacts on opportunists

K-selected species (competitors)

Intermediate and variable reproductive patterns
Positions of r-selected and K-selected
Species on Population Growth Curve
Number of individuals
Carrying capacity
K
K species;
experience
K selection
Number of individuals
r species;
experience
r selection
Time
OLD Fig. 6-14, p. 122
r-selected Opportunists and K-selected Species
OLD Fig. 6-15, p. 123
r-Selected Species
Dandelion
Cockroach
Many small offspring
r-selected
Opportunists
and K-selected
Species
Little or no parental care and protection of offspring
Early reproductive age
Most offspring die before reaching reproductive age
Small adults
Adapted to unstable climate and environmental conditions
High population growth rate (r)
Population size fluctuates wildly above and below carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
OLD Fig. 6-15a, p. 123
K-Selected Species
Elephant
Saguaro
r-selected
Opportunists
and K-selected
Species
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental conditions
Lower population growth rate (r)
Population size fairly stable and usually close to carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
OLD Fig. 6-15b, p. 123
Characteristics of Natural and
Human-Dominated Systems
Property
Natural Systems
Human-Dominated
Systems
Complexity
Biologically diverse
Biologically
simplified
Energy source
Renewable solar
energy
Mostly nonrenewable
fossil fuel energy
Waste production
Little, if any
High
Nutrients
Recycled
Often lost of wasted
Net primary
productivity
Shared among many
species
Used, destroyed, or
degraded to support
human activities
OLD Fig. 6-16, p. 124
Human Impacts on Ecosystems
Natural Capital Degradation
Altering Nature to Meet Our Needs
Reduction of biodiversity
Increasing use of the earth's
net primary productivity
Increasing genetic resistance
of pest species and disease
causing bacteria
Elimination of many natural
predators
Deliberate or accidental
introduction of potentially
harmful species into
communities
Using some renewable
resources faster than they can
be replenished
Interfering with the earth's
chemical cycling and energy
flow processes
Relying mostly on polluting
fossil fuels
OLD Fig. 6-17, p. 125
Four Principles of Sustainability
PRINCIPLES
OF
SUSTAINABILITY
OLD Fig. 6-18,
p. 126
Solutions
Principles of Sustainability
How Nature Works
Solutions:
Implications
of the Principles
of Sustainability
Runs on
renewable
solar energy.
Rely mostly on
renewable solar
energy.
Recycles
nutrients
and wastes.
There is little
waste
in nature.
Prevent and
reduce
pollution and
recycle
and reuse
resources.
Uses biodiversity
to maintain itself
and adapt to new
environmental
conditions.
Preserve
biodiversity
by protecting
ecosystem
services and
preventing
premature
extinction
of species.
Controls a
species'
population size
and resource use
by interactions
with its
environment
and other
species.
OLD Fig. 6-19, p. 126
Lessons for Us
Reduce births
and
wasteful resource
use to prevent
environmental
overload and
depletion and
degradation of
resources.
Lessons from Nature

We are dependent on the Earth and Sun

Everything is interdependent with everything else

We can never do just one thing

Earth’s natural capital must be sustained

Precautionary Principle

Prevention is better than cure

Risks must be taken