Brainstorm

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Brainstorm

• You and the person next to you will list 3
  examples of..
• Abiotic and biotic factors that affect population
  growth and decrease in size.

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Chapter 9

• Population Unit

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Population Dynamics

• Studying how populations change in size, density,
  age distribution, and population distribution.
• Size number of individuals
• Density how many are in a certain area
• Age distribution proportion of each age group
• Population distribution how the organisms
  arrange themselves in their habitat

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Population Distribution
Clumping Most common. Safety in numbers, social
interaction, mating and caring for young,
resources are clumped
Uniform Not as common. Used because of scarcity
of resources
Random Quite rare. Can be hard to determine
between truly random or largely clumpy
Most common.
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What goes up must come down

• Increases in population through birth or
  immigration
• Decreases in population through death or
  emigration.

Deaths Emigration
Change in Population
Births Immigration
Note You should know difference between
Immigration Emigration!
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Age Structure

• What is expected to happen if a large of the
  population is under the age of 10?
• What is expected to happen if a large of the
  population is over the age of 65?
• What is expected to happen if there is an equal
  distribution in age?

Growth will remain stable, then increase in 10-20
years
Growth will decrease
Growth remain stable
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What stage are you?

• Prereproductive stage Those not through puberty
  reproductively immature.
• Reproductive stage Those who are capable of
  reproduction
• Postreproductive stage Organisms that are too
  old to reproduce.
• Note while males are capable of reproduction
  longer, survival of the fittest can prevent
  them from breeding once they are too old.

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Old Bio StuffAbiotic vs. Biotic FactorsThat
limit population growth
Biotic
Abiotic

• Living factors
• Reproduction rates
• Food supply
• Habitat
• Resistance to disease
• Ability to adapt to change

• Not living
• Sunlight
• Temperature
• Climate
• Chemical environment

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Biotic potential growth
Environmental resistance decrease
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A population will increase if.

• A) Natality decreases
• B) Mortality increases
• C) Biotic potential increases
• D) The environmental resistance increases

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A population will increase if.

• A) Natality decreases
• B) Mortality increases
• C) Biotic potential increases
• D) The environmental resistance increases

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Any of these would take place for answer
C. Biotic potential growth
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Exponential or Logistic Growth Curve?
Boom and Bust
Boom then stable
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Logistic Growth

• Will see exponential growth at first introduction
  to new environment. Video to follow this
  lecture.
• Then, growth will be limited by environmental
  factors and will follow carrying capacity
• S shaped

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Clearer view of J and S
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Going up

• Intrinsic rate of increase (r) is the rate the
  population would grow if it had unlimited
  resources.
• Can be seen as the boom of the population.
• r species reproduce early in life, reproduce
  often, have many offspring each time.

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Coming down

• Overshoot occurs when the population booms and
  is too great for the resources to support
• Overshoot is followed by dieback, or the sudden
  decrease in population
• Reproductive time lag the amount of time it
  takes for the birth rate to fall and death rate
  to rise. If the time lag is too long,
  environmental damage can occur which further
  limits the carrying capacity.

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(No Transcript)
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Population Graphs
(b) Irregular
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Population Graphs
(a) Stable
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Population Graphs
(c) Cyclic
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Population Graphs

(

(d) Irruptive
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Oscillations of the Two Populations Over Time
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Population Density

• Density-dependent controls Limits populations
  that are too high.
• Examples competition for food, shelter, water
  disease parasites, predation
• Density-independent controls Decreases
  population regardless of size.
• Examples weather, temperature, natural
  disasters, habitat destruction, chemical changes
  in the environment

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Whos in control here?

• Top-down control (Predator Controls Prey)
• Structure of lower trophic levels depends on
  effect of consumers at high trophic levels.
• Bottom-up control (Prey Controls Predator)
• Structure depends on prey availability and
  nutrient content from low trophic levels
• Example Hare population is controlled either by
  the lynx killing it (top-down) or by large
  numbers of hare using up their food source
  (bottom-up)

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Lets talk about sexold bio stuff

• Asexual reproduction does not require sperm/egg.
  Mitosis cell splitting. Bacteria reproduce
  this way. Only 3 of all species use this form
• Sexual reproduction requires sperm/egg, but not
  necessarily intercourse/copulation
• Disadvantages
• Males dont give birth
• Increased chance of genetic defect/error
• Courtship and mating rituals can be complex
• Advantages (get your mind out of the gutter!)
• Genetic variety/diversity
• Parents can divide responsibilities

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What species are you?
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Remember You are SPECIAL
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Species
r-selected Species
K-selected Species

• Found at bottom of population curve
• Reproduce early in life
• Reproduce frequently
• Large numbers of offspring
• Little to no parental care
• Boom and bust populations
• Examples
• Frogs
• Cockroach
• Dandelions
• Mice
• Most insects

• Found at top of population curve
• Reproduce later in life
• Reproduce less frequently
• Have less offspring at one time
• Lower infant mortality
• Logistic graph (stable at top)
• Examples
• Humans
• Elephants
• Whales
• Long-living plants (oaks, rain forest trees)

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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
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R-selected Species or K-selected species?
HINT The Capybara is the largest rodent in the
world
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Survivorship Curves

• Early loss high infant mortality (fish, frogs)
• Constant loss death rate even among all ages
  (song birds)
• Late loss low infant mortality (humans,
  elephants)

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Isolation isnt best

• Problems when small, isolated populations exist.
• Founder effect small group is geographically
  isolated. May not have the genetic diversity to
  survive (coloring, fur cover, etc)
• Demographic bottleneck only a few surviving
  individuals may not have the genetic diversity to
  rebuild the population
• Genetic drift some individuals breed
• more and dominate the gene pool
• (wolves)
• Inbreeding related individuals in an
• area mate. Can increase genetic
• defects.

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Tying in a few things from

• Chapter 1

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Oops! I did it again

• Past mistakes that need to be stopped
• Reducing biodiversity by destroying, fragmenting
  and degrading habitats

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Oops! I did it again

• Past mistakes that need to be stopped
• Reducing biodiversity by simplifying natural
  ecosystems (monocultures one type)

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Oops! I did it again

• Past mistakes that need to be stopped
• Unintentional strengthening of pest species and
  anti-biotic resistant bacteria

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Oops! I did it again

• Past mistakes that need to be stopped
• Elimination of natural predators (wolves,
  cougars, buffalo, eagles)

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Oops! I did it again

• Past mistakes that need to be stopped
• Over-harvesting renewable resources

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Oops! I did it again

• Past mistakes that need to be stopped
• Interfering with natural cycles in natural

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Oops! I did it again

• Past mistakes that need to be stopped
• Over dependence on fossil fuels

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4 Guidelines for a Sustainable Future

• Our lives and economies are dependant on the
  earth and sun. They dont depend on us.
• Everything is interconnected.
• You cant change only one thing in nature
• We cannot sustain our civilization if we deplete
  the natural capital. We must live off the
  biological interest of that capital.

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Population Control
Solar Energy
PRINCIPLES OF SUSTAINABILITY
Nutrient Recycling
Biodiversity