Chapter 5 Key Concepts Species interactions Responses to changes in environmental conditions Factors determining number of species in a community Species Diversity and Ecological Stability ID: 679111
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Slide1
Biodiversity, Species Interactions, and Population Control
Chapter
5Slide2
Key Concepts
Species
interactions
Responses to changes in environmental
conditions
Factors determining number of species in a communitySlide3
Species Diversity and Ecological Stability
Many different species provide ecological stability
Some exceptions
Minimum threshold of species diversity
(10 - 40 producer species?)
Many unknowns
Net primary productivity (NPP)
Essential and nonessential speciesSlide4
Species diversity by latitude
AnimationSlide5
Types of Species
Native
Nonnative (invasive or alien)
Indicator-
Keystone
-
FoundationSlide6
Indicator Species
Provide early warnings of ecosystem damage
Indicator of water quality (trout)
Birds as environmental indicators
(affected by habitat loss, chemicals)
ButterfliesAmphibiansSlide7
Keystone Species
What is a keystone?
Keystone species play critical ecological roles
a. Pollination
b. Top predators
c. decomposition
EXAMPLES: Dung beetles, Sharks, bees, bats, wolves, alligatorsSlide8
Foundation Species
Relationship to keystones species
Play important roles in shaping communities
Elephants
Contributions of bats and birdsSlide9
Species Interactions
Interspecific competition
Predation
Symbiosis
= close long term association 2 or more species
A. Parasitism + -
B. Mutualism + +C. Commensalism + 0Slide10
Types of two species interactions animation.
AnimationSlide11
Species Interactions: Competition
Interspecific Competition
Fundamental niches
Fighting for limited resources
Competition from humansSlide12
Reducing or Avoiding Competition
Resource partitioning
Role of natural selection
Specialization and sharing of resources
Resource partitioning of warblersSlide13
Number of individuals
Number of individuals
Resource use
Resource use
Species 1
Species 2
Region
of
niche overlap
Species 1
Species 2
Resource Partitioning and Niche SpecializationSlide14
Resource Partitioning of Warbler SpeciesSlide15
How Do Predators Increase Their Chances of Getting a Meal?
Speed
Senses
Camouflage and ambush
Chemical warfare (venom)Slide16
Avoiding and Defending Against Predators
Escape
Senses
Armor
Camouflage
Chemical warfare
Warning colorationMimicryBehavior strategies
Safety in numbersSlide17
Span worm
Bombardier beetle
Viceroy butterfly mimics
monarch butterfly
Foul-tasting monarch
butterfly
Poison dart frog
When touched, the
snake caterpillar
changes shape to look
like the head of a snake
Wandering leaf insect
Hind wings of io moth
resemble eyes of a
much larger animal
How Species Avoid Predators
“If it is small and strikingly beautiful, it is probably poisonous. If it is strikingly beautiful and easy to catch, it is probably deadly.” - E.O Wilson
camouflage
Chemical warfare / Warning
mimicry
Deceptive behaviorSlide18
Parasites
Parasitism + -
Hosts
Inside or outside of hosts
Harmful effects on hosts
Important ecological roles of parasitesSlide19
Mutualism + +
Both species benefit
Pollination
Benefits include nutrition and protection
Mycorrhizae -
fungi that helps plants extract nutrients and water from soil
Gut inhabitant mutualismSlide20
Oxpeckers and black rhinoceros
Clown fish and sea anemone
Lack of mycorrhizae fungi on
juniper seedlings in sterilized soil
Fig. 6-7, p. 117
Examples of Mutualism
© 2006 Brooks/Cole - Thomson
Mycorrhizae fungi on juniper
seedlings in normal soilSlide21
Commensalism + 0
Species interaction that benefits one and has little or no effect on the other
Example: Small plants growing in shade of larger plants
Epiphytes
Forehead mitesSlide22
Bromeliad CommensalismSlide23
Ecological Succession: Communities in Transition
What is ecological succession?
(Gradual change in species composition)
Primary succession
= establishment of communities on nearly lifeless ground (no soil) ex. glacier retreat, landslide, lava, abandoned parking lot
Secondary succession- community disturbed, soil remains. Burned / cut forests, polluted stream, floodSlide24
Two types of ecological succession animation.
AnimationSlide25
Limits on Population Growth
Biotic potential
(capacity for growth)
Intrinsic rate of increase (
r
)
(assumes unlimited resources)No indefinite population growthEnvironmental resistance= all the factors that limit population growthCarrying capacity (K
) - determined by biotic potential & enviro resistance Slide26
Carrying capacity (
K
)
Environmental
resistance
Biotic
potential
Exponential
growth
Population Growth Curves
Time (
t
)
Population size (
N
)Slide27
Exponential and Logistic Population Growth
Resources control population growth
Exponential growth -
J-shaped curve
Logistic growth -
S-shaped curveSlide28
Logistic Growth of Sheep Population
Overshoot
Carrying Capacity
Year
Number of sheep (millions)
2.0
1.5
1.0
.5
1800
1825
1850
1875
1900
1925Slide29
When Population Size Exceeds Carrying Capacity
Switch to new resources, move or die
Overshoots
Reproductive time lag
Population dieback or crash
Human Famines -
Irish potato famine 1845 - 1 million dead
Factors controlling human carrying capacity- technology has increased carrying capacity for humansSlide30
Exponential Growth, Overshoot and Population Crash of Reindeer
Population
Overshoots
Carrying
Capacity
Population
crashes
Carrying capacity
Year
Number of sheep (millions)
2,000
1,500
1,000
500
0
1910
1920
1930
1940
1950