Population Ecology

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Population Ecology

• Every second.5 people are born, 2 people die,
• .net gain 3 people.

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Population Ecology

• Deals with the of individuals of a particular
  species that are found in an area and how and why
  those change or remain fixed over time.

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Population ecologists study

• How populations respond to its environment
• Competition for resources, predations, disease
  and other environmental pressures

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Population Growth

• J-shaped curve
• 1. Exponential growth growth rate under ideal
  conditions
• 2. Uncheck growth (carrying capacity not yet
  met)

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J-shaped

• Exponential growth!

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S-Shaped Curve

• 1. An S-shaped curve shows that the population
  grows slowly at first then increases more and
  more quickly.

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S-Shaped Curve
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• 2. At carrying capacity, growth of the
  population will remain the same.

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• 3. Carrying capacity is the number of organisms
  that an environment can support indefinitely.

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• a. Births will approximately equal deaths.
• B. When the population overshoots the carrying
  results in LIMITING factors death to outnumber
  births.

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• C. Limiting Factor is a factor that will limit
  population growth.
• 1) Food availability
• 2) Disease
• 3) Predators
• 4) Space

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Reproductive Patterns

• A. Rapid life history (example mosquitoes)
• a. Rapid reproduction
• b. High number of offspring

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Reproductive Patterns

• c. Small body size
• d. Organisms mature rapidly
• e. Reproduce early
• f. Organisms have a short life span

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• B. Slow life history (example elephant)
• a. Slow reproduction
• b. Low number of offspring
• Large body size

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• d. Organisms mature slowly
• e. Reproduce late in life
• f. Organisms have a long life span
• g. Organisms tend to have parental care

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Population density growth

• Population density is the number of individuals
  in a given area.

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• DensityDEPENDENT factor
• Factor that limits population size or density

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• A. Disease (example HIV)
• B. Competition
• C. Predators
• D. Parasites
• Food
• Water
• Territory
•  

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• Density -INDEPENDENT factor
• Usually a weather related event.
• It affects ALL populations regardless of size.

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• A. Temperature
• B. Storms
• C. Floods
• D. Drought
• E. Volcanic eruption

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• Predator-prey relationship
• Predators affect prey populations
• B. Prey affect predator populations

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• Intraspecies competition
• A. Space
• B. Food
• C. Water
• D. Reproduction

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• Invasive Species
• uncontrolled competition

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Project World Population Growth

• Demography
• Study of HUMAN population size, density,
  distribution, movement, BIRTH rates death rates.

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World Population Growth
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Year Population
1 200 million
1000 275 million
1500 450 million
1650 500 million
1750 700 million
1804 1 billion
1850 1.2 billion
1900 1.6 billion
1927 2 billion
1950 2.55 billion
1955 2.8 billion
1960 3 billion
1965 3.3 billion
1970 3.7 billion
1975 4 billion
1980 4.5 billion
1985 4.85 billion
1990 5.3 billion
1995 5.7 billion
1999 6 billion
2006 6.5 billion
2009 6.8 billion
2011 7 billion
2025 8 billion
2050 9.4 billion
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• Humans can alter their environment thus affect
  the POPULATION GROWTH RATE.

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• 1. Famine
• 2. Eradicate Disease
• 3. War
• 4. Better food production

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Calculating Growth Rate

• Growth rate (r) birth rate (b) I death rate
  (d) E

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• Immigration movement of individuals into a
  population
• Emigration movement of individuals into a
  population

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• Doubling time time needed for population to
  double in size
• Zero population growth birthrate death rate

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• Birthrate number of live births per 1000 in a
  given year
• Death rate number of deaths per 1000 in a
  given year

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Demographics of Countries

• Demographics applied science that deals with
  population statistics.

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Developed countries

• 1. Low birth rates
• 2.Low infant mortality rates. (the of infant
  deaths per 1000 live births)

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Developed countries

• 1996 US 7.5/1000 for infant morality
• World average 62/1000

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Developed countries

• 3.Usually have longer life expectancy

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Developed countries

• 4.Examples of developed countries
• US, Canada, Sweden, Germany, France, Australia,
  Japan

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Developing Countries

• Moderately developed countries
• Examples
• 1. Mexico
• 2. Turkey
• 3. Thailand
• (most S. American nations)

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• Less developed countries
• Examples
• 1. Bangledesh
• 2. Niger
• Ethiopia
• Laos
• Cambodia

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• These countries have
• High birth and mortality rates than developed
  countries
• Short life spans

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• Another factor to examine is the replacement
  level fertility. This is number of children a
  couple must have to replace themselves.
  Replacement rate is 2.1 children in developed
  countries.

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• The replacement rate in developing countries is
  2.7 children.

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Age Structure of Countries

• In order to predict future population it is
  important to know the age structure.

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Age Structure of Countries

• Age structure is the number and proportion at
  each age in a population. The number of males
  and females at each age.

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• The overall structure of the age tells whether
  the population is increasing, stable or shrinking.

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• Stable growth approximately the same number of
  individuals at each age grouping

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• Rapid growth a large proportion of the
  population is 19 years old or younger

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• Slow growth a large proportion of population is
  55 years old or younger

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• Declining growth the largest portion of the
  population is 20-40 years, smaller groups are
  younger

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