Download Chp 5: Biodiversity, Species Interactions, and Population Control

Chp 5: Biodiversity, Species Interactions, and Population Control

Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction?
•
Habitat
•
Hunted: early 1900s
•
Partial recovery
•
Why care about sea otters?

______________________________________________________________________________
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______________________________________________________________________________
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______________________________________________________________________________
Examples:

Southern Sea Otter:

Purple Sea Urchin:
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Video: Otter feeding:
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Video: Kelp forest (Channel Islands):

Video: Coral spawning:

Population Size of Southern Sea Otters Off the Coast of So. California (U.S.):
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Science Focus: Why Are Protected Sea Otters Making a Slow Comeback?
•
Low
•
Prey for
•
Cat
•
Thorny-headed
•
Toxic
•
_______________________________and other toxins
•
_____________________________________________
5.1 How Do Species Interact?

Species Interact in Five Major Ways
1.
Competition -
– what does this mean?
2.
•
Interspecific – _________________________________ species
•
Intraspecific – __________________________________species
Predation -
3. Parasitism 4. Mutualism 5. Commensalism 
Most Consumer Species Feed on Live Organisms of Other Species
•
Predators may capture prey by
1.
2. __________________________
3. __________________________
4. __________________________
5. __________________________
6. __________________________

Prey may avoid capture by
1. ___________________________________
2. ___________________________________
3. ___________________________________
4. ___________________________________
5. ___________________________________
6. ___________________________________

Defensive Mechanisms:

Many species have evolved ________________________________________________ to warn off predators

Many species have evolved ____________________________________________ to warn of potential danger.

_____________________________________Mimicry - Harmless species evolve characteristics that mimic
unpalatable, dangerous, or poisonous species.

_____________________________________Mimicry - Two unpalatable or dangerous species evolve to look
alike.

Camouflage -

Coevolution:

Animation: Life history patterns

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Animation: Capture-recapture method

Video: Salmon swimming upstream

5.2 How Can Natural Selection Reduce Competition between Species?

Some species develop
with other species for resources.

Some Species Evolve Ways to Share Resources
•
•
•

Resource partitioning Reduce niche overlap
Use shared resources at different
 ____________________
 ____________________
 ____________________
Competing Species Can Evolve to Reduce Niche Overlap
that allow them to reduce or avoid competition

Competitive Exclusion Principle -

Sharing the Wealth: Resource Partitioning 5.3 What Limits the Growth of Populations?

No population can continue to grow indefinitely because of
and because of
among species for those resources.

Populations Have Certain Characteristics
•



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
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Populations differ in
 ______________________________________________
 ______________________________________________
 ______________________________________________
Population dynamics
Changes in population characteristics due to:
• ___________________________________________________________________________________
• ___________________________________________________________________________________
• ___________________________________________________________________________________
• ___________________________________________________________________________________
Population Distribution - Most Populations Live Together in Clumps or Patches
Most Populations Live Together in Clumps or Patches
Why clumping?
• Species tend to cluster where ___________________________________________________
• Groups have a better chance of finding ____________________________________________
• Protects some animals from _____________________________________________________
• Packs allow some to get ________________________________________________________
• Temporary groups for ______________________ and ________________________ for young
•
Populations Can Grow, Shrink, or Remain Stable
• Population size governed by
 _______________________
 _______________________
 _______________________
 _______________________
• Population change = (births +
) – (deaths +

Age structure
• ______________________ age
• ______________________age
• ______________________ age

No Population Can Grow Indefinitely: J-Curves and S-Curves

Biotic potential –

Intrinsic rate of increase (r) –
)

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Individuals in populations with high r
• Reproduce ___________________________________________________________________
• Have __________________________ generation times
• Can _________________________________ many times
• Have __________________ offspring each time they reproduce
Active Figure: Exponential growth

Size of populations limited by
• _________________________________________
• _________________________________________
• _________________________________________
• _________________________________________
• Exposure to too many __________________________________________________________________
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When a Population Exceeds Its Habitat’s ________________________________, Its Population Can __________
Carrying capacity: _____________________________________
Reproductive time lag may lead to
• Dieback (
)
Damage may reduce area’s
Exponential Growth, Overshoot, and Population Crash of a Reindeer

Species Have Different Reproductive Patterns

r-Selected species,
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K-selected species,

Positions of r- and K-Selected Species on the S-Shaped Population Growth Curve
(usually
species)
(usually
Survivorship Curves

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Genetic Diversity Can Affect the Size of Small Populations
Genetic Drift
• Demographic
• _______________________________________
• _______________________________________
Minimum viable population size

Under Some Circumstances Population Density Affects Population Size
•
•


Density-independent controls
• ________________________________
• ________________________________
•
Density-dependent population controls
• _________________________________
• _________________________________
• _________________________________
• __________________________________
•
Several Different Types of Population Change Occur in Nature
• Stable • Irruptive • Cyclic fluctuations, boom-and-bust cycles
• Top-down population regulation • Bottom-up population regulation • Irregular
Population Cycles for the Snowshoe Hare and Canada Lynx
species)

Humans Are Not Exempt from Nature’s Population Controls:
• Ireland: Potato crop in 1845 –
•
Bubonic plague: Fourteenth century –
•
AIDS: Global epidemic –
5.4 How Do Communities and Ecosystems Respond to Changing Environmental Conditions?
 The structure and species composition of communities and ecosystems change in response to changing
environmental conditions through a process called
.
 Natural ecological restoration
• ________________________ succession
• _________________________ succession
 Some Ecosystems Start from Scratch = _________________________Succession:
• No
in a terrestrial system
• No
in an aquatic system
• Early successional plant species =
Ex.
• Midsuccessional plant species =
• Late successional plant species =
 Some Ecosystems Do Not Have to Start from Scratch = ___________________________ Succession
• Some soil
in a terrestrial system
• Some bottom sediment
in an aquatic system
• Ecosystem has been
• ___________________________________
• ___________________________________
• ___________________________________
 Primary and secondary succession:
• Tend to increase
• Increase species
and
among species
 Primary and secondary succession can be interrupted by
• ________________
• ________________
• ________________ of forests
• ________________of grasslands
• ________________ by nonnative species
 Succession Doesn’t Follow a Predictable Path
• Traditional view
•
Balance of
and a
• Current view
• Ever-changing mosaic of patches of
• Mature late-successional ecosystems
 State of
disturbance and change
 Living Systems Are Sustained through Constant Change
• Inertia, persistence
• Ability of a living system to
• Resilience
• Ability of a living system to be restored through
after a moderate disturbance
• Tipping point - any additional
can cause the system to change in an abrupt and
usually
way that often involves
.
•
Factors that affect how and at what rate succession occurs:
• _________________________ - one set of species makes an area suitable for species with
different niche requirements, but less suitable for itself.
 For example, as lichens and mosses gradually build up soil on a rock in primary
succession, herbs and grasses can colonize the site and crowd out the pioneer
community of lichens and mosses.
• _________________________ - some early species hinder the establishment and growth of
other species. Inhibition often occurs when plants release toxic chemicals that reduce
competition from other plants.
 For example, pine needles dropped by some species of pines can make the underlying
soil acidic and inhospitable to other plant species. Succession then can proceed only
when a fire, bulldozer, or other human or natural disturbance removes most of the
inhibiting species.
• __________________________ - late successional plants are largely unaffected by plants at
earlier stages of succession because they are not in direct competition with them for key
resources.
 For example, shade tolerant trees and other plants can thrive in the understory of a
mature forest (Figure 5-17) because they do not need to compete with the taller species
for access to sunlight.