Biodiversity, Species Interactions, and Population Control

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Biodiversity, Species Interactions, and
Population Control

• Chapter 5

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Southern Sea Otter
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Core Case Study Southern Sea Otters Are They
Back from the Brink of Extinction?

• Habitat
• Hunted early 1900s
• Partial recovery by the late 2007

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Why care about them?
5

• Why care about sea otters?
• Ethics
• Keystone species (Eat sea Urchins)
• Tourism dollars

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Science Focus Why Should We Care about Kelp
Forests?

• Kelp forests one of the most biologically
  diverse marine habitat
• One blade of kelp can grow 2 feet in a single day
• Major threats to kelp forests
• Sea urchins
• Pollution from water run-off
• Global warming (changing of the waters temp)

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Purple Sea Urchin
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Video Kelp forest (Channel Islands)
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Video Coral spawning
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5-1 How Do Species Interact?

• Concept 5-1 Five types of species
  interactionscompetition, predation, parasitism,
  mutualism, and commensalismaffect the resource
  use and population sizes of the species in an
  ecosystem.

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Species Interact in Five Major Ways

• Interspecific Competition over same resources
• Predation
• Parasitism
• one gains, one loses (not always death)
• Mutualism both gain
• Commensalism one gains, the other gets no
  benefits

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Interspecific Competition
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Most Species Compete with One Another for Certain
Resources

• Competition for same limited resources (food,
  shelter, space)
• Competitive exclusion principle no 2 species can
  occupy exactly the same ecological niche for very
  long

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Most Consumer Species Feed on Live Organisms of
Other Species (1)

• Predators may capture prey by
• Walking
• Swimming
• Flying
• Pursuit and ambush
• Camouflage
• Chemical warfare

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Most Consumer Species Feed on Live Organisms of
Other Species (2)

• Prey may avoid capture by
• Camouflage
• Chemical warfare
• Warning coloration
• Mimicry
• Deceptive looks
• Deceptive behavior

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Some Ways Prey Species Avoid Their Predators
Stepped Art
Fig. 5-2, p. 103
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Video Salmon swimming upstream
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Predator and Prey Species Can Drive Each Others
Evolution

• Intense natural selection pressures between
  predator and prey populations
• Coevolution

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Coevolution A Langohrfledermaus Bat Hunting a
Moth
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Predation
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Video Otter feeding
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Some Species Feed off Other Species by Living on
or in Them

• Parasitism
• Parasite-host interaction may lead to coevolution
• Hosts point of view parasites bad
• Population level POV promote biodiversity, keep
  populations in check

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Parasitism Tree with Parasitic Mistletoe, Trout
with Blood-Sucking Sea Lampreys
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Parasitism

• Ticks

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In Some Interactions, Both Species Benefit

• Mutualism
• Nutrition and protection relationship
• Gut inhabitant mutualism vast armies of
  bacteria, break down food
• How is a Cow like a termite?
• Cooperation between species?

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Mutualism
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Mutualism Oxpeckers Clean Rhinoceros Anemones
Protect and Feed Clownfish
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• Centipede

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In Some Interactions, One Species Benefits and
the Other Is Not Harmed

• Commensalism
• Epiphytes
• Birds nesting in trees
• Army ants and silverfish

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Commensalism Bromiliad Roots on Tree Trunk
Without Harming Tree
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Chapter 5, section 1

• Q1 What are the 5 different ways that species
  interact with each other? Give an example of
  each. Describe what is unique about each
  interaction type.
• Q2 Describe a trait possessed by the southern
  sea otter that helps it a) catch prey and b)
  avoid being preyed upon
• Q3 Compare Competitive exclusion principle with
  coevolution

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• Q5 Why would detritus feeders and decomposers
  not considered predators?
• Q6 What methods/ways help predators catch their
  prey?
• Q7 What ways have the prey developed to avoid
  being caught?
• Q9 Why can coevolution be described like an
  arms race?
• Q10 Explain how each of the species interactions
  can affect the population sizes of species in
  ecosystems.

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5-2 How Can Natural Selection Reduce Competition
between Species?

• Concept 5-2 Some species develop adaptations
  that allow them to reduce or avoid competition
  with other species for resources.

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Question

• Do species want to compete for niche space?

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Some Species Evolve Ways to Share Resources

• Resource partitioning
• Reduce niche overlap, increase species diversity
• Use shared resources at different
• Times
• Places
• Ways

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Competing Species Can Evolve to Reduce Niche
Overlap
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Sharing the Wealth Resource Partitioning
Stepped Art
Fig. 5-8, p. 107
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Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Specialist Species of Honeycreepers
Amakihi
Kona Grosbeak
Crested Honeycreeper
Akiapolaau
Apapane
Maui Parrotbill
Unkown finch ancestor
Fig. 5-9, p. 108
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Honey creepers on Hawaii

• Evolved into different species, each
  concentrating on different food resources
• Evolutionary divergence-speciation

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Chapter 5, section 2 questions

• Q11 How does resource partitioning increase
  species diversity?
• Q12 How did the warblers reduce competition when
  eating insects on spruce trees?
• Q13 How is the evolutionary progress of honey
  creepers an example of evolutionary divergence?

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Question

• How many humans can live on the Earth?
• How many cockroaches?

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5-3 What Limits the Growth of Populations?

• Concept 5-3 No population can continue to grow
  indefinitely due to
• limitations on resources
• competition among species for those resources.

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What information can be used to describe the
differences between 2 different populations of
the same creature?
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Populations Have Certain Characteristics (1)

• Populations differ in
• Distribution
• Numbers
• Age structure
• These values are Population dynamics

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Populations Characteristics can change

• due to
• Temperature change
• Presence of disease, organisms or harmful
  chemicals
• Resource availability
• Arrival or disappearance of competing species

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Population distributions
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Most Populations Live Together in Clumps or
Patches (1)

• Different types of population distribution
• Clumping
• Uniform dispersion (what would cause this?)
• Random dispersion (what would cause this?)

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Most Populations Live Together in Clumps or
Patches (2)

• Why clumping?
• Species tend to cluster where resources are
  available
• Groups have a better chance of finding clumped
  resources
• Herds protect some animals from predators
• Packs allow some predators to get prey
• Temporary groups for mating and caring for young

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Why does the population of the US continues to
increase, despite the birthrate falling below 2.0
kids per mother?
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Populations Can Grow, Shrink, or Remain Stable (1)

• Population size governed by
• Births
• Deaths
• Immigration
• Emigration
• Population change
• (births immigration) (deaths
  emigration)

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Populations Can Grow, Shrink, or Remain Stable (2)

• Age structure
• Pre-reproductive age
• Reproductive age (if greatest , greatest growth)
• Post-reproductive age
• Excluding emigration/immigration, a population
  that has an even distribution amongst the groups
  will remain stable.

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How would you describe the US population, in
terms of age?

• Pre-reproductive
• Reproductive
• Post-reproductive

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Population Growth Rates

• Biotic potential capacity for pop growth
• Low (elephants, whales)
• High (insects and bacteria)
• Intrinsic rate of increase (r)
• Steepness of curve
• Individuals in populations with high r
• Reproduce early in life
• Have short generation times (adaptable)
• Can reproduce many times
• Have many offspring each time they reproduce

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Better than roaches and bunnies

• A species of bacteria could carpet the entire
  surface of the earth 1 foot deep in 36 hours, if
  there was nothing to control its population
  numbers.
• What stops it from doing so?

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Environmental resistance

• Environmental resistance
• Combo of all factors which limit growth
• Size of populations limited by
• Light
• Water
• Space
• Nutrients
• Exposure to too many competitors, predators or
  infectious diseases

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No Population Can Grow Indefinitely J-Curves
and S-Curves (3)

• Carrying capacity (K)
• Max population sustained indefinitely
• Exponential growth (j-curve)
• (even 1-2 growth is exponential)
• Logistic growth (s-curve)
• Rapid growth followed by leveling off

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The first part of any population graph should be
a J

• As population nears carrying capacity, graph
  should change into an s-curve

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No Population Can Continue to Increase in Size
Indefinitely
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Logistic Growth of a Sheep Population on the
island of Tasmania, 18001925
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When a Population Exceeds Its Habitats Carrying
Capacity, Its Population Can Crash

• Carrying capacity not fixed, dependent on
  environmental factors (food, conditions)
• Reproductive time lag may lead to overshoot
• Dieback (crash)
• Overshoot Damage may reduce areas carrying
  capacity

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Science Focus Why Are Protected Sea Otters
Making a Slow Comeback?

• Low biotic potential
• Prey for orcas
• Cat parasites (from kitty liter flushed)
• Thorny-headed worms (seabirds)
• Toxic algae blooms (urea, fertilizer)
• PCBs and other toxins
• Oil spills

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Population Size of Southern Sea Otters Off the
Coast of So. California (U.S.)
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Exponential Growth, Overshoot, and Population
Crash of a Reindeer
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Story of the Reindeer

• 26 introduced to island in Bering Sea
• No predators, pop soared
• Food is slow growth lichens and mosses
• Pop starved, crashed to 8 in 1950

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Species Have Different Reproductive Patterns

• r-Selected species, opportunists
• Capacity for high rate of pop increase
• Little or no care of offspring
• Large populations
• K-selected species, competitors
• Reproduce later in life
• Long life spans
• Small number of offspring, care
• Small Populations

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Positions of r- and K-Selected Species on the
S-Shaped Population Growth Curve
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Genetic Diversity Can Affect the size, success of
Small Populations

• Founder effect few individuals start new colony
• Demographic bottleneck few individuals survive
  catastrophe
• Genetic drift random changes to gene frequencies
  in pop that lead to unequal reproductive success
• Inbreeding increase of defective genes in small
  pop
• Use above to estimate minimum viable population
  size

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Population Density and Population Size

• Density independent pop controls
• Mostly abiotic like weather, forest fires
• Density-dependent population controls
• Predation
• Parasitism
• Infectious disease
• Competition for resources

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Several Different Types of Population Change
Occur in Nature

• Stable
• Irruptive
• external conditions (temp)
• Cyclic fluctuations, boom-and-bust cycles (more
  than once, internal)
• Top-down population regulation (bunnies-lynx)
• Bottom-up population regulation (lemmings)
• Irregular (no drastic increases)

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Population Cycles for the Snowshoe Hare and
Canada Lynx (notice general delay in lynx crashes)
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Humans Are Not Exempt from Natures Population
Controls

• Ireland
• Potato crop in 1845
• Bubonic plague
• Fourteenth century
• AIDS
• Global epidemic

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Questions on 5.3

• Q15 Why do populations tend to live in clumps?
• Q17 What are the 3 age group categories in a
  populations age structure
• Q21 Which group grasshoppers or elephants have
  a high biotic potential? Why?
• Q25 Use the concepts of carrying capacity to
  explain why there are always limits to population
  growth in nature
• Q30 Distinguish between r-selected species and
  k-selected species and give an example of each
  type. Which are humans?

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White-tailed deer
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Case Study Exploding White-Tailed Deer
Population in the U.S.

• 1900 deer habitat destruction and uncontrolled
  hunting
• 1920s1930s laws to protect the deer
• Results of current population explosion for deer
• Lyme disease
• Deer-vehicle accidents
• Eating garden plants and shrubs
• Ways to control the deer population

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Solutions to the consequences of the exploding
deer population

• List at least 3 different solutions that would
  result in a sustainable deer population.
  (several in textbook or come up with your own
• For each solution, describe
• The economic and environmental cost
• Changes in the population dynamics over time
• Main causes for change in the carrying capacity
  for deer

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Modeling population growth lab

• Vernier

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5-4 How Do Communities and Ecosystems Respond to
Changing Environmental Conditions?

• Concept 5-4 The structure and species
  composition of communities and ecosystems change
  in response to changing environmental conditions
  through a process called ecological succession.

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Mt. St. Helens-Secondary Succession
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Primary Succession Candidate
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Candidates for primary succession
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Communities and Ecosystems Change over Time
Ecological Succession

• Natural ecological restoration
• Primary succession
• Starts from bare rock
• Secondary succession
• Does not start from bare rock
• New home construction (why?)

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Some Ecosystems Start from Scratch Primary
Succession

• No soil in a terrestrial system
• No bottom sediment in an aquatic system
• Early successional plant species, pioneer
• Midsuccessional plant species
• Late successional plant species

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Primary Ecological Succession
Balsam fir, paper birch, and white spruce forest
community
Jack pine, black spruce, and aspen
Heath mat
Small herbs and shrubs
Lichens and mosses
Exposed rocks
Time
Fig. 5-16, p. 116
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Some Ecosystems Do Not Have to Start from
Scratch Secondary Succession (1)

• Some soil remains in a terrestrial system
• Some bottom sediment remains in an aquatic system
• Ecosystem has been
• Disturbed
• Removed
• Destroyed

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Natural Ecological Restoration of Disturbed Land
(secondary)
Mature oak and hickory forest
Young pine forest with developing understory of
oak and hickory trees
Shrubs and small pine seedlings
Perennial weeds and grasses
Annual weeds
Time
Fig. 5-17, p. 117
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Some Ecosystems Do Not Have to Start from
Scratch Secondary Succession (2)

• Primary and secondary succession
• Tend to increase biodiversity
• Increase species richness and interactions among
  species
• Primary and secondary succession can be
  interrupted by
• Fires
• Hurricanes
• Clear-cutting of forests
• Plowing of grasslands
• Invasion by nonnative species

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Factors that affect the rate of succession

• Facilitation
• one set of species makes area makes area suitable
  for following species, less for themselves
  (mosses/lichens and grasses)
• Inhibition
• hinder establishment and growth of species ex
  pine trees
• Tolerance
• unaffected by plants in earlier stages (mature
  trees vs shade plants)

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Succession Doesnt Follow a Predictable Path

• Traditional view
• Balance of nature and a climax community
• Achieves equilibrium
• Current view
• Succession Doesnt follow a predictable path
• Ever-changing mosaic of patches of vegetation
• Mature late-successional ecosystems
• State of continual disturbance and change, not
  permanent equilibrium

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Living Systems Are Sustained through Constant
Change

• Inertia, persistence
• Ability of a living system to survive moderate
  disturbances
• Resilience
• Ability of a living system to be restored through
  secondary succession after a moderate disturbance
  
• Tipping point

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Tropical Rain Forest

• Ecosystem is persistent but is not resilant

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Arthropod biodiversity lab
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UN project Questions

• Give 2 examples of r-selected and k-selected
  species that live in your country
• Obtain a picture of a park or wilderness area of
  your country. Where in terms of ecological
  succession (early, mid, late, climax) does your
  picture represent? State evidence to support your
  choice
• Indicate specific examples from your country for
  the following, (avoid examples that could show up
  globally)
• a) Interspecific competition
• b) Predator and Prey
• c) Parasite and host
• d) Mutualism
• e) Commensalism
• f) For each example given describe the population
  distribution pattern