Populations

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Populations
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Population or not?

• The monkeys in a rainforest

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• E. coli bacteria growing in a petri dish

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Humans on Earth
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The cats in my neighborhood.
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The trees in a forest
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Population

• A group of organisms of the same species that
  live within a given area

Ostriches are nomadic, wandering in small groups.
Aspen trees are quick to pioneer areas that have
been disturbed by fire.
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a) Dispersion

• Give an example of each type

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Gannets nesting
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Solitary tree sloth
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School of fish
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Population density (total population size per
unit of area)
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c) Growth Rate

• (Births Immigrants) - (Deaths Emigrants)
• Population Size

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One bacterium divides in two in 20 minutes. This
process continues for several days.

• Sketch the population growth graph.

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Exponential growth curve (J shape)
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Exponential growth is a rapid population
increase due to an abundance of resources.
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• Day 1 0.01 Day 16 327.68
• Day 2 0.02 Day 17 655.36
• Day 3 0.04 Day 18 1310.72
• Day 4 0.08 Day 19 2621.44
• Day 5 0.16 Day 20 5242.88
• Day 6 0.32 Day 21 10,485.76
• Day 7 0.64 Day 22 20,971.52
• Day 8 1.28 Day 23 41,943.04
• Day 9 2.56 Day 24 83,886.08
• Day 10 5.12 Day 25 167,772.16
• Day 11 10.24 Day 26 335,544.32
• Day 12 20.48 Day 27 671,088.64
• Day 13 40.96 Day 28 1,342,177.20
• Day 14 81.92 Day 29 2,684,354.40
• Day 15 163.84 Day 30 5,368,708.80

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Logistic growth curve (S shape) isdue to a
population facing limited resources.

• Carrying capacity is the maximum number of
  individuals in a population that the environment
  can support

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Ecological factors limit population growth

• Density-dependent limiting factors are affected
  by the number of individuals in a given area.

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Density-dependent limiting factors are affected
by the number of individuals in a given area.

• Competition for food, shelter
• Predation
• Parasitism and disease

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Density-independent limiting factors limit a
populations growth regardless of the density

• Unusual weather
• Natural disasters
• Human activities

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Density - dependent or density independent
factor?

• Tornado
• independent
• Food supply
• dependent
• Amount of rainfall
• independent
• Temperature
• independent
• Competition for drinking water
• dependent
• Spreading of a disease
• dependent

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Reproductive Strategies
r-strategists (rapid growth) K-strategists (near carrying capacity)
Early reproduction Short life span High mortality Little parental care Large number of offspring Insects, amphibians, bony fish Exponential growth curve Reproduce late in life Long life span Low mortality High parental care Few offspring Humans, other large mammals, sharks Logistic growth curve
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Survivorship curves
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Choose type I, II, or III for

• Humans
• Fish
• Lizards
• Birds
• Insects
• Lions
• Squirrels
• Plants

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Population Pyramids
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Who are the circled people? What is significant
about them?
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Most Populated Cities (1/6/2007)
Rank City / Urban area Country Population Land area(in km2) Population Density/km2
1 Tokyo/Yokohama Japan 33,200,000 6,993 4750
2 New York Metro USA 17,800,000 8,683 2050
3 Sao Paulo Brazil 17,700,000 1,968 9000
4 Seoul/Incheon South Korea 17,500,000 1,049 16,700
5 Mexico City Mexico 17,400,000 2,072 8400
6 Osaka/Kobe/Kyoto Japan 16,425,000 2,564 6400
7 Manila Philippines 14,750,000 1,399 10,550
8 Mumbai India 14,350,000 484 29,650
9 Delhi India 14,300,000 1,295 11,050
10 Jakarta Indonesia 14,250,000 1,360 10,500

64 Atlanta USA 3,500,000 5,083 700
http//www.citymayors.com/statistics/largest-citie
s-population-125.html
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Growth curve for the human population
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http//www-popexpo.ined.fr/eMain.html
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expo.ined.fr/eMain.html
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Doubling Time

• The amount of time needed for a population to
  double
• Doubling time (in years)
• 70
• annual percent growth rate
• The worlds annual growth rate is about 1.75.
  What is the current doubling time?
• 40 years

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What is an ecological footprint?

• The demands a person places
• on the environment in terms of
• land, water, food, waste, fibers,
• etc.

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• "It's up to us to make a global effort to limit
  population growth - or we can wait until the
  environment does it for us."