Effect of Fertility Rates on Population Growth

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Effect of Fertility Rates on Population Growth

• Replacement-level fertility (RLF)
• number of children that a couple should have to
  replace both
• parents
• (Developed counties 2.1
• (Some developing countries 2.5-
• due to child mortality)

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Effect of Fertility Rates of Population Growth

• Total fertility rate (TFR)
• average number of children that a woman will
  have in her reproductive years (0 - 5)
• Most useful measure of fertility for projecting
  future populations.

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Effect of Fertility Rates of Population Growth

• in 2004, TFR 2.8 (greater than global
  sustainable rate of 2.1)
• 1.5 in developed countries (down from 2.5 in
  1950)
• 3.1 in developing countries
• (down from 6.5 in 1950)

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Global Total Fertility Rates
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Population growth

• TFR needs to drop to 2.1 in order to stabilize
  the population.(Takes into account infant
  mortality)
• TFR gt RLF pop growth
• TFR RLF steady population
• TFR lt RLF pop slow down

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10 Factors affecting Birth rate and Fertility rate

• Average level of education and affluence
• Importance of children as a part of the labor
  force
• Urban areas (wrt access to family planning)
• Cost of raising and educating children
• Education and employment opportunity for women
• Infant mortality rate
• Average age of marriage and 1st child
• Availability of pension system
• Availability of legal abortions
• Birth control/religion

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Factors affecting Death rate

• Population increase is not necessarily due only
  to increased birth rate, but also decreased death
  rate.
• Life expectancy
• Infant mortality rate of babies/1000/year
• Most important measure of quality of life since
  it is linked to so much of society!

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Population Density

• of indiv. of a species
• unit of area
• A better way to describe the size of a
  population
• ex. 270,000,000 people 29 people/Km2 in the US
• 9,166,605 Km2

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What Causes Populations to Change in Size?

• Dependent on
• Birth rate (b )
• Death rate (d )
• Immigration (i )
• Emigration (e )

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Birth and Death Rate

• b birth _ or Births per
  thousand Total population 1000
• d death or Deaths per
  thousand Total population 1000
• ex. b 23, 452/942,721 0.025 2.5
• Same as 25/1000 0.025 2.5

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What Causes Populations to Change in Size?

• Rate of change ( r )
• Total births - total deaths/ total population
• r 23,452 -17, 228 0.0066 .66
• 942,721
• 2. birth rate (b) -death rate (d)
• r 25 - 18 0.007 0.7
• 1000 1000
• 3. (Total births total immigration) -
• (total deaths total emigration) / total
  population
• r (23,452 9842)-(17, 228 2450)
  942,721
• 0.014 1.4
• 4. (birth rate (b) immigration rate(i)) -
  (death rate (d) emigration rate (e) ) x 100
• r (25 10) - (18 3) 0.014 1.4
• 1000 1000
• r (b I) (d e) This is the one we will
  use

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Immigration (i )

• Migration of individuals INTO an area
• Emigration (e )
• Migration of individuals OUT OF an area

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Doubling Time

• Time to take for a population with a stable
  growth rate to double in size
• Doubling Time ( td )
• td 70 or .7
• r r
• Ex. Braz
• il will double its population in how many years
  with the present growth rate of 1.7?
• A .7/0.017 or 70/1.7 41.2 years

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Maximum Population Growth(MPG)

• Influenced by Biotic Potential
• The maximum rate at which the population of a
  given species can increase when there are no
  limits on its rate of growth
• MPG is always exponential under ideal
  conditions

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You figure out the growth Rate of a Pop

• Remember r (b - d ) (i - e )
• b .01 d .005
• i .001 e .01
• So now Calculate growth rate
• and Calculate doubling time
• What does it mean when your r value is negative?
• Population growth is in decline.

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Determining future Pops

• Remember N (t) N0ert
• N(t) population after t years
• N0 initial population size
• r growth rate
• t time

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You Determine the future Pop of Duttania

• Remember N (t) N0ert
• The island of Duttania has 435 people. Their
  growth rate is 2. What will be the population
  after 10 years?
• A 531 people.