Populations
Population or not?
The monkeys in a rainforest
E. coli bacteria growing in a petri dish
Humans on Earth
The cats in my neighborhood.
The trees in a forest
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.
BioEd Online
a) Dispersion
• Give an example of each type
Gannets nesting
Solitary tree sloth
School of fish
b) Population density (total population size per unit of area)
c) Growth Rate(Births + Immigrants) - (Deaths + Emigrants)
Population Size
One bacterium divides in two in 20 minutes. This process continues for several days.
• Sketch the population growth graph.
Exponential growth curve (J shape)
Exponential growth is a rapid population
increase due to an abundance of resources.
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
Logistic growth curve (S shape) is
due to a population facing limited resources. •Carrying capacity is the maximum number of individuals in a
population that the environment can support
Ecological factors limit population growth
• Density-dependent limiting factors are affected by the number of individuals in a given area.
Density-dependent limiting factors are affected by the number of individuals in a
given area.
• Competition for food, shelter
• Predation• Parasitism and
disease
Density-independent limiting factors limit a population’s growth regardless of the density
• Unusual weather• Natural disasters• Human activities
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
Reproductive Strategiesr-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
Survivorship curves
Choose type I, II, or III for
• Humans• Fish• Lizards• Birds• Insects• Lions• Squirrels• Plants
Population Pyramids
Who are the circled people? What is significant about them?
Most Populated Cities (1/6/2007)
RankCity / Urban
areaCountry Population
Land area(in km2)
Population Density/km2
1 Tokyo/Yokohama
Japan 33,200,000 6,9934750
2 New York Metro
USA 17,800,000 8,6832050
3 Sao Paulo Brazil 17,700,000 1,968 9000
4 Seoul/Incheon
South Korea 17,500,000 1,04916,700
5 Mexico City Mexico 17,400,000 2,072 8400
6 Osaka/Kobe/Kyoto
Japan 16,425,000 2,5646400
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-cities-population-125.html
Growth curve for the human population
http://www-popexpo.ined.fr/eMain.html
Doubling Time• The amount of time needed for a
population to double
• Doubling time (in years) =
70
annual percent growth rate
• The world’s annual growth rate is about 1.75%. What is the current doubling time?
• 40 years
What is an ecological footprint?
• The demands a person places
on the environment in terms of
land, water, food, waste, fibers,
etc.
• "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."