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Population Dynamics

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Mutualism sea anemone protects clownfish from predators; clownfish is territorial and protects anemone from predators and shares food ... – PowerPoint PPT presentation

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Title: Population Dynamics


1
Population Dynamics
  • Ch. 35

2
Measuring Populations
  • Population density of individuals of a
    particular species per unit area

3
Measuring Populations, cont.
  • Sampling used to estimate size of population
  • Quadrats count all organisms in a block and use
    this to estimate population size
  • Indirect counting count nests, burrows, etc
    instead of organisms
  • Mark recapture trap animals, mark them,
    release, recapture and count marked vs. unmarked

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5
Limiting population growth
  • Limiting factor a condition that can limit
    population growth
  • Ex space, food, disease
  • Carrying capacity the number of organisms in a
    population that the environment can maintain
  • Birth rate and death rate are about equal

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Limiting population growth
  • Density-dependent factors a factor that limits
    population growth more as the population density
    increases
  • Ex food, disease that spreads by contact
  • Density-independent factors a factor that
    limits population and is unrelated to population
    density
  • Ex extreme weather

8
Types of population growth
  • Exponential population multiplies by a constant
    factor at constant time intervals
  • there are few factors that stop overall growth
  • Also known as J-curve

9
Types of population growth
  • S-curve population begins growing
    exponentially, but environmental factors begin to
    limit growth population stops growing or may
    begin to decrease

10
Types of population growth
  • Boom and bust increase rapidly (boom) and then
    decrease rapidly (bust)

11
Population interactions
  • Interspecific competition two or more species
    rely on the same limited resource
  • Competitive exclusion when one species succeeds
    over the other due to limited resources
  • Niche each organisms unique living
    arrangement, such as habitat, food, time when
    active, etc

12
Population interactions
  • Predation an interaction in which one organism
    eats another
  • Predator doing the eating
  • Prey being eaten
  • Both predator and prey have evolved with
    adaptations to enhance survival
  • Ex camouflage, hunting in packs, warning
    coloration

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15
Prey adaptations
16
Population interactions
  • Symbiotic relationships a close relationship
    between species in which one of the species lives
    in or on the other
  • Parasitism the parasite obtains food at the
    expense of the other organism (host)
  • Mutualism both organisms benefit
  • Commensalism one organisms benefits and the
    other is neither helped nor harmed

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18
Parasitism blowfly larvae kill purple martin
chick
19
Mutualism sea anemone protects clownfish from
predators clownfish is territorial and protects
anemone from predators and shares food
20
Commensalism grey whale carries barnacles
whale not harmed nor helped, barnacles have more
access to food
21
Disturbances in communities
  • Ecological succession community change when new
    species colonize disturbed area
  • Primary succession community arises in lifeless
    area without soil
  • Ex volcano creating new island
  • Secondary succession community arises in
    disturbed area with soil
  • Ex growth in plowed farm field

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23
Primary succession growth on lava rock
24
Secondary succession after forest fire
25
Disturbances in communities
  • Pioneer species predominant species in the
    early stages of succession tend to be small,
    fast-growing, and fast-producing
  • Succession proceeds through many stages until it
    reaches a stable end point called the climax
    community

26
Pioneer species can grown on rock and will help
form soil
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