Download PPT Ch5 Population Ecology

Chapter 5
Population Ecology
Populations Growth
Population Growth
Three factors can affect population size:
number of births
the number of deaths
the number of individuals that enter or
leave the population.
* Simply put, a population will increase or
decrease in size depending on how many
individuals are added to it or removed from it
Immigration & Emmigration
Immigration
the movement of individuals into an
area, is another factor that can cause a
population to grow.
Emigration
the movement of individuals out of an
area, can cause a population to
decrease in size.
 In 1911, 25 reindeer were introduced on Saint
Paul Island in the Pribolofs off Alaska. The
population grew rapidly and nearly
exponentially until about 1938, when there
were over 2000 animals on the 41-squaremile island. The reindeer badly overgrazed
their food supply (primarily lichens) and the
population “crashed.” Only eight animals
could be found in 1950. A similar sequence of
events occurred on Saint Matthew Island from
1944 through 1966. [After Krebs (1972) after V. B. Scheffer
(1951). The Rise and Fall of a Reindeer Herd. Science 73: 356–362.]
Exponential Growth
Populations growing without restriction!
If a population has abundant space
and food, and is protected from
predators and disease, then
organisms in that population will
multiply and the population size will
increase.
Exponential Growth
Exponential growth occurs when
the individuals in a population
reproduce at a constant rate.
Under ideal conditions with
unlimited resources, a
population will grow
exponentially.
Exponential population growth
is described by the simple differential equation dN/dt = rN
where,change in number of individuals (dN) per Change in time (dt) =
growth rate (rN)
Logistic Growth
Logistic growth occurs when a
population's growth slows or stops
following a period of exponential growth.
As resources become less available,
the growth of a population slows or
stops. The general, S-shaped curve of
this growth pattern, called logistic growth
 Carrying Capacity The number or the largest number of individuals
that a given environment can support.
Variations of the Logistic Model
 If food becomes scarce, the population will
experience an overshoot by becoming larger
than the spring carrying capacity and will
result in a die-off, or population crash.
environmental resistance. : the sum of the
environmental factors (such as drought, mineral deficiencies,
and competition) that tend to restrict the biotic potential of an
organism
Population-same species, same place, same time
Characteristics of Populations
Three important characteristics of a
population
• geographic distribution
• Density
• growth rate
Geographic
distribution, or
range, is a term
that describes the
area inhabited by
a population.
Clumped- Most common
social, protection, resources
Uniform- predator-territoriality
Allelopathy
Random- less common
Resources evenly distributed
Population Density
Population density is the number of
individuals per unit area
.
 The population of
saguaro cactus in
the desert plant
community has a
low density,
whereas other
plants in that
community have a
relatively high
density.
Factors that Restrict the Size
of a Population
Limiting Factors of
Environmental Resistance
Density-Dependent Limiting
Factors
1. The degree of influence depends on the
size of the population.
2. Examples: competition, predation,
parasitism, stress caused by crowding,
disease
3. Seldom totally eliminate a population
4. Some populations are self-controlling in
that they have mechanisms to reduce
competition – delayed maturation caused
by malnutrition, migration, cannibalism.
Density-Independent Limiting Factors
1. The degree of influence is not related to
population size.
2. Examples: pollution, habitat destruction,
natural disasters, weather
3. Usually just reduce the population below
the cc. but they have the ability to totally
eliminate a population
Density Independent Factors
Influencing Populations
Density Dependent Factors
Influencing Populations
Types of Species
Generalist
large niches
tolerate wide range of environmental
variations
do better during changing environmental
conditions
Specialist
narrow niches
 more likely to become endangered
 do better under consistent environmental
conditions
21
r and k strategists
 Depending upon the characteristics of the organism,
organisms will follow a biotic potential or carrying capacity
type reproductive strategy
The r-strategists (Type III)
1. High biotic potential – reproduce very fast
2. Are adapted to live in a variable climate
3. Produce many small, quickly maturing offspring = early
reproductive maturity
4. “Opportunistic” organisms
The K-strategists (Type I)
1. Adaptations allow them to maintain population values
around the carrying capacity
2. They live long lives
3. Reproduce late
4. Produce few, large, offspring
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Survivorship Curves
k-strategist
r-strategist

Survivorship curves show the
distribution of individuals in a
population according to age

Humans and most mammals
have a Type I survivorship
curve because death primarily
occurs in the older years.

Birds have a Type II
survivorship curve, as death at
any age is equally probable.

Trees have a Type III
survivorship curve because
very few survive the younger
years, but after a certain age,
individuals are much more
likely to survive.

/
Community
Relationships
24
Types of Species
Native species normally live and thrive
in a particular ecosystem
Nonnative species are introduced - can
be called exotic or alien
Indicator species serve as early
warnings of danger to ecosystem- birds
& amphibians
Keystone species are considered of
most importance in maintaining their
ecosystem
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Identify some of the factors that could cause a change in the number of red crabs on
Christmas Island. Predict what would happen to the red crab population as the result of
a (1) drought, a (2) hurricane, or the introduction of a (3)predator to the ecosystem.
Christmas Island red crab
Gecarcoidea natalis
 The land crab that is endemic to
Christmas Island in the Indian
Ocean. An estimated that 43.7
million adult red crabs lived on
Christmas Island alone. The
accidental introduction of the
yellow crazy ant is believed to
have killed about 10–15 million of
these in recent years.
 Christmas Island red crabs are
well known for their annual mass
migration to the sea to lay their
eggs in the ocean.
Christmas Island Land Crab
Keystone Species
 Christmas Island's biodiversity - land crabs are a
keystone species in the forest ecology: they dig
burrows, turn over the soil, and fertilise it with their
droppings.
 Seedlings that were previously eaten by crabs started
to grow and, as a result, changed the structure of the
forest.
 Weeds also spread into the rainforest because there
are no crabs to control them.
Factors that Influence Population Size
Density-dependent factors- the size of
the population will influence an
individual’s probability of survival.
Density-independent factors- the size
of the population has no effect on the
individual’s probability of survival.
Exponential Growth Model
Intrinsic growth rate- under ideal
conditions, with unlimited resources, the
maximum potential for growth.
Resource Patitioning
Predation
Predation- the use of one species as a
resource by another species.
True predators- kill their prey.
Herbivores- consume plants as prey.
Parasites- live on or in the organism they
consume.
Parasitoids- lay eggs inside other
organisms.
Mutualism
Mutualism- A type of interspecific
interaction where both species benefit.
Commensalism
Commensalism- a type of relationship in
which one species benefits but the other is
neither harmed nor helped.
Community Ecology
Each species has a particular ecological
niche or role that it plays in an ecosystem.
Competitive Exclusion Principle
Two species that have exactly the same
requirements cannot coexist in exactly the
same habitat.
r-Selected Species
Cockroach
Dandelion
Many small offspring
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
K-Selected Species
Saguaro
Elephant
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
The Giant Panda: Specialized and
Endangered
 Classic k-strategist =
specialist
 Feeds exclusively on
bamboo (1/3 of body
weight)
 Habitat fragmentation has
created “habitat islands” of
bamboo in southwestern
China due to human
encroachment.
 12 protected reserves in
China.
Why Are Panda Faced With
Extinction?
 Illegal poaching (pelt brings in $40,000-60,000).
 Only one cub per female survives each year.
 Gestation period = 22 months
 Picky about mates. Find each other through
scent, become isolated due to habitat
fragmentation.
 Habitat islands interrupt natural migration to
adjacent areas when bamboo population
crashes in local areas.
 Approximately 700 panda left between zoos and
the wild.
What Are Indicator Species?
 Indicator species serve as early warnings of
damage to a community.
 Birds and butterflies are migratory and are
excellent indicators of the environment. They do
not return to areas along their migratory routes
where deforestation has occurred or where
broad spectrum pesticides have been applied.
 Amphibians are also a universal indicator of
environmental degradation as they respire
through their skin.
Indicator Species
 As indicator species,
amphibians may be
sending us an
important message
about the health of
the global
environment.
 They don’t need us,
but we and other
species need them.
Golden toads – once prevalent in
Costa Rica’s cloud forest have
disappeared.
Indicator Species in New England
Why are species in
trouble
HIPPCO
What Are Keystone Species?
A keystone species holds a community
together, when it disappears, so does the
biological community. Elimination of a
keystone species dramatically alters the
structure and function of a community.
American Alligator – a Keystone
Species
 Largest North
American reptile;
only humans are
their predator.
 Hunted nearly to
extinction for
exotic meat, and
leather to make
shoes and
pocketbooks,
and for sport.
Ecological Niche of American
Alligator
Dig gator holes that collect freshwater
during the dry season which serve as
refuges for aquatic life, and supply
freshwater and food for many animals.
Ecological Niche of American
Alligator
Alligator nesting mounds serve as nesting
and feeding sites for herons and egrets
Ecological Niche of American
Alligator
Alligator eat large numbers of predatory
gar fish and help maintain healthy
numbers of game fish such as bass and
bream.
Ecological Niche of American
Alligator
 As alligators
move from gator
holes to nesting
sites, they keep
areas of open
water free of
invading
vegetation. This
helps to maintain
healthy
ecosystems with
flowing water.
American Alligator Protection
 In 1967, the US
Government placed
the American alligator
on the Endangered
Species List, which
protected it from
hunting.
 By 1975, the
American alligator
populations
rebounded
successfully.
Keystone Species Youtube series
E.O. Wilson
“The loss of a keystone species is like a
drill accidentally striking a power line. It
causes lights to go out all over”
Interaction between Species
Chapter 5
Competition
The outcome is negative for both groups
Symbiosis
Benefits both participants
Predation and parasitism
The outcome benefits one and is detrimental to
the other.
Symbiosis
Recall- endosymbiont theory
 Describes a relationship
between two organisms
beneficial to both
enhances each organism’s
chance of persisting
 Each partner called a
symbiont
 E.g. reindeer and bacteria
in the gut
The result is food for
reindeer, home for bacteria
Amazing Adaptations
 Parasitism
 Mutualism and
Commensalism
Predation and Parasitism
 Relationship is beneficial for predator or parasite and
negative for prey or host.
 Predation- One organism (predator) feeds on other live
organisms (prey).
 Parasitism- One organism (the parasite) lives on, in, or within
another (the host).
North Woods Ecosystem Population Fluctuations
Carrying Capacity
-------------------------------------------------K-species
exponential
r-species
The Food Web of the Harp Seal
Food webs are complex because most
species feed on several trophic levels.
Harp seal (shown at 5th level)
Feeds on flatfish (4th level)
But also feed on foods from 2nd – 4th
A species that feeds on several levels placed in
a category one above the highest level it feeds
on.
Community Level Interactions
Sea Otter Manages Kelp Forest
 Indirect and more complicated community wide
affects species have on one another.
 Sea otter of the Pacific Ocean
Came close to extinction because of over hunting for
fur
Feed on shellfish (abalone, sea urchins)
Where sea otters abundant kelp beds abundant and
few sea urchins
Otters affects the abundance of kelp
Community Level Interactions
Sea otters have community level effect
Where more kelp is present more habitat for
many species
Keystone species
A species that has a large effect on its
community or ecosystem
Holistic view
Ecological community is more than the sum
of its parts
Lead into Chapter 12 Food
Crash
landing
ROOST
Hindfeet
The Evolution of Life on Earth
 Mammals
More capable brain
and faster metabolism
Placental uterus one
key to mammalian
success
Interaction between Species
Chapter 5
Competition
The outcome is negative for both groups
Symbiosis
Benefits both participants
Predation and parasitism
The outcome benefits one and is detrimental to
the other.
Symbiosis
Recall- endosymbiont theory
 Describes a relationship
between two organisms
beneficial to both
enhances each organism’s
chance of persisting
 Each partner called a
symbiont
 E.g. reindeer and bacteria
in the gut
The result is food for
reindeer, home for bacteria
Amazing Adaptations
 Parasitism
 Mutualism
 Commensalism
 Amazonian Rain Forest Brazil
 The First Agriculture 60mya –Symbiosis
Extincitions
Polar Bear and Global Warming
Amazing Diversity of Organisms & Sea Dragons
Competitive Exclusion Principle
Two species that have exactly the same
requirements cannot coexist in exactly the
same habitat.
Predation and Parasitism
 Relationship is beneficial for predator or parasite and
negative for prey or host.
 Predation- One organism (predator) feeds on other live
organisms (prey).
 Parasitism- One organism (the parasite) lives on, in, or within
another (the host).
North Woods Ecosystem Population Fluctuations
Carrying Capacity
-------------------------------------------------K-species
exponential
r-species
The Food Web of the Harp Seal
Food webs are complex because most
species feed on several trophic levels.
Harp seal (shown at 5th level)
Feeds on flatfish (4th level)
But also feed on foods from 2nd – 4th
A species that feeds on several levels placed in
a category one above the highest level it feeds
on.
Community Level Interactions
Sea Otter Manages Kelp Forest
 Indirect and more complicated community wide
affects species have on one another.
 Sea otter of the Pacific Ocean
Came close to extinction because of over hunting for
fur
Feed on shellfish (abalone, sea urchins)
Where sea otters abundant kelp beds abundant and
few sea urchins
Otters affects the abundance of kelp
Community Level Interactions
Sea otters have community level effect
Where more kelp is present more habitat for
many species
Keystone species
A species that has a large effect on its
community or ecosystem
Holistic view
Ecological community is more than the sum
of its parts
Lead into Chapter 12 Food
Crash
landing
ROOST
Hindfeet
Fossil Record
 Most of what we know of the history of life on
earth comes from fossils (SJ Gould)
 Give us physical evidence of organisms
Show us internal structure
 Uneven and incomplete record of species
We have fossils for 1% of species believed to have
lived on earth
Some organisms left no fossils, others decomposed,
others have yet to be found.
 Other info from ancient rocks, ice core, DNA
 The whale as an example Other evidence
here
Speciation
Northern
population
Early fox
population
Spreads
northward
and
southward
and
separates
Arctic Fox
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Southern
population
Gray Fox
Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.
Adapted to heat
through lightweight
fur and long ears,
legs, and nose, which
give off more heat.
Speciation
 Two species arise from one
 Requires Reproductive isolation





Geographic: Physically separated
Temporal: Mate at different times
Behavioral: Bird calls / mating rituals
Anatomical: Picture a mouse and an elephant hooking up
Genetic Inviability: Mules
 Allopatric
 Speciation that occurs when 2 or more populations of a species
are geographically isolated from one another
 The allele frequencies in these populations change
 Members become so different that that can no no longer
interbreed
 See animation
 Sympatric
 Populations evolve with overlapping ranges
 Behavioral barrier or hybridization or polyploidy
TAKE HOME #2
Macroevolution is the cumulative result of
a series of microevolutionary events
Typically seen in fossil record
Nobody around to see the small, gene pool
changes over time.
COEVOLUTION: Interaction Biodiversity
Species so tightly connected, that the
evolutionary history of one affects the
other and vice versa.
Ant Farmers of the Amazon
Coevolution
 Interactions between species can cause
microevolution
Changes in the gene pool of one species can cause
changes in the gene pool of the other
 Adaptation follows adaptation in something of
a long term “arms race” between interacting
populations of different populations
The Red Queen Effect
 Can also be symbiotic coevolution
Angiosperms and insects (pollinators)
Corals and zooxanthellae
Rhizobium bacteria and legume root nodules
And NUH is the letter I use to spell Nutches,
Who live in small caves, known as Niches, for hutches.
These Nutches have troubles, the biggest of which is
The fact there are many more Nutches than Niches.
Each Nutch in a Nich knows that some other Nutch
Would like to move into his Nich very much.
So each Nutch in a Nich has to watch that small Nich
Or Nutches who haven't got Niches will snitch.
-On Beyond Zebra (1955)
Dr. Seuss
Niches
 A species functional role in an ecosystem
 Involves everything that affects its survival and reproduction
 Includes range of tolerance of all abiotic factors
 Trophic characteristics
 How it interacts with biotic and abiotic factors
 Role it plays in energy flow and matter cycling
 Fundamental Niche
 Full potential range of physical chemical and biological
conditions and resources it could theoretically use if there was
no direct competition from other species
 Realized Niche
 Part of its niche actually occupied
 Generalist vs. Specialist
 Lives many different places, eat many foods, tolerate a wide
range of conditions vs few, few, intolerant…
 Which strategy is better in a stable environment vs unstable?
POLLENPEEPERS
POLLENPEEPER EVOLUTION
Number of individuals
Niche Overlap
Niche
separation
Generalist species
with a narrow niche
Niche
breadth
Region of
niche overlap
Resource use
Generalist species
with a broad niche
Competition Shrinks Niches
Competition and Community Diversity
•Species evolve to
minimize
competition and
niche overlap
•Results in a
diverse matrix of
differing species
within a
community
What’s This Niche Stuff Got to do with
Evolution and Biodiversity?
Hmmmmm….
Let’s think about three key points….
The more niches you have in an ecosystem…
The more of a generalist species you are…
The more of a specialist species you are…
Era
Period
Millions of
Cenozoic
years ago
Quaternary
Today
Bar width represents relative
number of living species
Species and families experiencing
mass extinction
Extinction
Tertiary
65
Extinction
Mesozoic
Cretaceous
Jurassic
180
Extinction
Triassic
250
Carboniferous
345
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Triassic: 35% of animal families, including
many reptiles and marine mollusks.
Extinction
Permian: 90% of animal families, including
over 95% of marine species; many trees,
amphibians, most bryozoans and
brachiopods, all trilobites.
Extinction
Devonian: 30% of animal families,
Extinction
Ordovician: 50%
of animal families,
Permian
Paleozoic
Current extinction crisis caused
by human activities.
Devonian
Silurian
Ordovician
Cambrian
500
Extinction
 Local, ecological and true extinction
 The ultimate fate of all species just as death is for all individual
organisms
 99.9% of all the species that have ever existed are now extinct
 To a very close approximation, all species are extinct
 Background vs. Mass Extinction
 Low rate vs. 25-90% of total
 Five great mass extinctions in which numerous new
species (including mammals) evolved to fill new or vacated
niches in changed environments
 10 million years or more for adaptive radiations to rebuild
biological diversity following a mass extinction
 Extinctions open up new opportunities for speciation and
adaptive radiation..BUT you can have too much of a good
thing!
Factors Affecting Extinction Rates
 Natural Extinctions
 Climate change
 Cataclysmic event (volcano, earthquake)
 Human Activities










Habitat Loss/Fragmentation
Introduction of exotic/invasive species
Pollution
Commercial harvesting
Accidental killing (tuna nets)
Harassing
Pet Trade
Urbanization
Damming/Flooding
Agricultural conversion
Extinction in the Context of Evolution
If
the environment changes rapidly and
The species living in these environments do not
already possess genes which enable survival in
the face of such change and
Random mutations do not accumulate quickly
enough then,
All members of the unlucky species may
die
Biodiversity
 Speciation – Extinction=Biodiversity
 Humans major force in the premature extinction of
species. Extinction rate increased by 100-1000
times the natural background rate.
 As we grow in population over next 50 years, we are
expected to take over more of the earth’s surface
and productivity. This may cause the premature
extinction of up to a QUARTER of the earth’s current
species and constitute a SIXTH mass extinction
 Genetic engineering won’t solve this problem
 Only takes existing genes and moves them around
 Know why this is so important and what we
are losing as it disappears….
USING EVOLUTION AND GENETICS TO
INFORM CONSERVATION
 EcoRegions Approach
 Identifying biodiversity “hotspots” and focusing conservation
efforts on maintaining those ecosystems
 Ex. Tropics, Appalachian Mountains, etc.
 “Umbrella Species” Conservation
 Conserve one “sexy”, species and you conserve several others
because if the interactions they have with one another
 Keystone species concept
 Species Survival Plan (SSP)
 Zoo captive breeding programs
 Population genetics in wild populations
 Ex. Cheetahs, Primates, Bears, etc.
Federal and International Legislation
 Endangered Species Act (1973)
Protection for endangered and threatened plant and
animal species & their habitats
 Effectiveness??? Exemptions are often granted if
• No alternatives to the project
• National or regional significance of project
• Benefits outweigh those of any alternatives
 CITES (late 1970s)-prohibits trade and
commerce of threatened and endangered
species
By 1998: signed by 144 countries
Niche is
the species’ occupation
and its
Habitat
location of species
(its address)
112
Niche
A species’ functional role in its
ecosystem; includes anything affecting
species survival and reproduction
1.Range of tolerance for various physical and
chemical conditions
2.Types of resources used
3.Interactions with living and nonliving
components of ecosystems
4.Role played in flow of energy and matter
cycling
113
Niche
Fundamental niche: set of
conditions under which a
species might exist in the
absence of interactions with
other species
Realized niche: more
restricted set of conditions
under which the species
actually exists due to
interactions with other
114
Biodiversity
Biodiversity
increases with speciation
decreases with extinction
Give-and-take between speciation
and extinction  changes in
biodiversity
Extinction creates evolutionary
opportunities for adaptive radiation
of surviving species
115
Coevolution
 Evolutionary change
One species acts as a selective force on
a second species
Inducing adaptations
that act as selective force on the first
species
Example:
1. Wolf and Moose
2. Acacia ants and Acacia trees
2. Yucca Plants and Yucca moths
3. Lichen
Extinction
Background extinction - species
disappear at a low rate as local
conditions change
Mass extinction - catastrophic, widespread events --> abrupt increase in
extinction rate
Five mass extinctions in past 500 million
years
Adaptive radiation - new species evolve
during recovery period following mass
117
How do species move?
Humans (accidental and intended)
Animals (sticky seeds and scat)
Wind and ocean currents (+ or -)
Land bridges
Stepping stone islands
affected by climactic changes
(glaciation)
ocean levels
short-term weather patterns
118
Nonnative Species
Nonnative plant species are invading
the nation's parks at an alarming rate,
displacing native vegetation and
threatening the wildlife that depend on
them
At some, such as Sleeping Bear Dunes
National Lakeshore in Michigan, as
much as 23 percent of the ground is
covered with alien species, and the rate
of expansion is increasing dramatically.
119
Indicator Species
a species whose status provides
information on the overall condition
of the ecosystem and of other
species in that ecosystem
 reflect the quality and changes in
environmental conditions as well as
aspects of community composition
120
Keystone Species
 A keystone is the stone at the top of an arch that supports
the other stones and keeps the whole arch from falling
 a species on which the persistence of a large number of other
species in the ecosystem depends.
 If a keystone species is removed from a system
 the species it supported will also disappear
 other dependent species will also disappear
 Examples
 top carnivores that keep prey in check
 large herbivores that shape the habitat in which other species live
 important plants that support particular insect species that are prey
for birds
 bats that disperse the seeds of plants
121
Species
Interaction
122
Competition
Any interaction between two or more
species for a resource that causes a
decrease in the population growth or
distribution of one of the species
1.
Resource competition
123
Competition
124
Resource Competition
125
Competition
Any interaction between two or more
species for a resource that causes a
decrease in the population growth or
distribution of one of the species
1.
2.
Resource competition
Preemptive competition
126
127
Competition
Any interaction between two or more
species for a resource that causes a
decrease in the population growth or
distribution of one of the species
1.
2.
3.
Resource competition
Preemptive competition
Competitive exclusion
128
Competitive Exclusion
129
Competition
Any interaction between two or more
species for a resource that causes a
decrease in the population growth or
distribution of one of the species
1.
2.
3.
4.
Resource competition
Preemptive competition
Competition exploitation
Interference competition
130
Competition
131
PREDATION
132
Predator Adaptations
Prey detection and recognition
sensory adaptations
distinguish prey from non-prey
133
134
135
136
Predator Adaptations
Prey detection and recognition
sensory adaptations
distinguish prey from non-prey
Prey capture
passive vs. active
individuals vs. cooperative
137
138
139
140
141
142
Predator Adaptations
Prey detection and recognition
sensory adaptations
distinguish prey from non-prey
Prey capture
passive vs. active
individuals vs. cooperative
Eating prey
teeth, claws etc.
143
144
145
146
147
Prey Adaptations
Avoid detection
camouflage, mimics,
diurnal/nocturnal
148
149
150
151
152
Prey Adaptations
Avoid detection
camouflage, mimics,
diurnal/nocturnal
Avoid capture
flee
resist
escape
153
154
155
156
Prey Adaptations
Avoid detection
camouflage, mimics,
diurnal/nocturnal
Avoid capture
flee
resist
escape
Disrupt handling (prevent being
eaten)
struggle?
157
158
Herbivory
Herbivore needs to find most nutritious
circumvent plant defenses
159
160
Herbivory
Herbivore needs to find most nutritious
circumvent plant defenses
Herbivory strong selective pressure on plants
structural adaptations for defense
chemical adaptations for defense
161
162
163
Herbivory
164
Herbivory
165
Herbivory
166
Symbiosis:
Mutualists,
Commensalist
s and
Parasites
167
Symbiosis and symbiotic relationship are
two commonly misused terms
Translation of symbiosis from the Greek
literally means “living together”
Both positive and negative interactions
168
Mutualism
DEFINITION:
An interaction between two
individuals of different species
that benefits both partners in
this interaction
169
Yucca and Yucca Moth
Yucca’s only
pollinator is the
yucca moth. Hence
entirely dependent
on it for dispersal.
Yucca moth
caterpillar’s only
food is yucca seeds.
Yucca moth lives in
yucca and receives
shelter from plant.
170
Lichen (Fungi-Algae)
Symbiotic relationship of algae
and fungae…results in very
different growth formas with and
without symbiont.
What are the benefits to the
fungus?
171
Commensalists
Benefit from the
host at almost no
cost to the host
Eyelash mite and
humans
Us and starlings or
house sparrows
Sharks and remora
172
Parasites and
Parasitoids
Parasites: draw resources from host
without killing the host (at least in the short
term).
Parasitoids: draw resources from the host
and kill them swiftly (though not
necessarily consuming them).
173
Parasitic wasps
Important
parasites of
larvae.
In terms of
biological
control, how
would this differ
from predation?
ovipositor
174
Ecological
Processes
175
Ecological Succession
Primary and Secondary Succession
gradual & fairly predictable change in species
composition with time
•some species colonize & become more
abundant;
•other species decline or even disappear.
176
Ecological Succession
Gradual changing environment in
favor of new / different species /
communities
177
178
Primary
Succession
Glacier
Retreat
179
180
181
Bibliography
1.
2.
3.
4.
5.
6.
7.
8.
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10.
11.
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13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
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182