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Announcements Mar 3, 2004

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Announcements September 11, 2006 Study Abroad Program Africa/Asia/Middle East Open House Wednesday, Sept. 13 3:30 - 5:30 PM 101 International Studies Building – PowerPoint PPT presentation

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Title: Announcements Mar 3, 2004


1
Announcements
September 11, 2006 Study Abroad
Program Africa/Asia/Middle East Open
House Wednesday, Sept. 13 330 - 530 PM 101
International Studies Building
2
Announcements
September 11, 2006 New handout available for
students taking the course for honors
credit. (additional assignment choice
added) Make sure you come talk to me before
starting your assignment!
3
Announcements
September 11, 2006 Schedule for next
week Monday (Sept 18th) - brief review of what
you need to know for first exam. Wednesday (Sept
20th) - first exam Friday (Sept 22) - no class
4
Which of these age distributions has a Type III
survivorship curve?
A
B
C
Type III survivorship curve
Very high mortality among the young
5
Which of these age distributions has a Type III
survivorship curve?
A
Type III survivorship curve
Very high mortality among the young
6
Type I survivorship curve Survival is high until
old age
  • Examples
  • Dall sheep
  • Humans in developed countries


7
Type II survivorship curve
Mortality is spread evenly among all age groups
  • Example
  • Many species of birds


8
Type 1
Type 1
Type 2 or 3
9
Carrying Capacity Number of individuals of a
species that can be indefinitely sustained in a
given area.
10
Environmental Resistance
  • Environmental ResistanceAny factor (limiting
    factor) in the environment influencing carrying
    capacity. Four main factors
  • Raw material availability
  • Energy availability
  • Waste accumulation and disposal
  • Organism interaction

11
Note This equation is provided only to help.
You do not need to memorize it. You will not be
asked about the equation on a test.
Logistic Equation
12
Causes of population crashes
  • Population size can sometimes overshoot carrying
    capacity
  • Environmental resistance factors can change,
    lowering carry capacity
  • When population gt carrying capacity,
  • death rates gt birth rates
  • Population crashes!!

13
Example 1 bacterial population crash due to
toxic waste accumulation
14
Example 2 Population cycling due to organism
interaction
  • Hare population
  • birth rate limited by food availability
  • death rate determined by predators, food
  • Lynx population
  • birth and death rate determined by food
    availability (hares)

15
Example 2 Population cycling due to organism
interaction
  • Start both have low population density
  • Hares high food, low predators pop increase
    over next generations
  • Lynx as hares increase, more food pop
    increase
  • Hares when high pop density, increased
    competition for food and increased predation
    low birth rate high death rate sharp pop
    decrease
  • Lynx when high pop density and few hares, low
    food low birth rate high death rate sharp
    pop decrease
  • Back to start

16
Population Cycles

17
Remember Several factors influence population
growth rate
Birthrate
Death rate
Sex Ratio
Age Distribution
Immigration
Emigration
But, there are also additional things about the
individuals that influence how the population
grows
18
Life history traits characteristics of an
individual that influence survival and
reproduction
Age at maturity
Atlantic Salmon
African elephant
House Mouse
3-6 years
11 - 20 years
2 months
19
Life history traits characteristics of an
individual that influence survival and
reproduction
Number of offspring produced
Atlantic Salmon
African elephant
House Mouse
1 calf every 3-8 years
1,500 to 8,000 eggs once
5-8 young every month
20
Life history traits characteristics of an
individual that influence survival and
reproduction
Number of reproductive events
Atlantic Salmon
African elephant
House Mouse
1
6-12
3 - 10
21
Life history traits characteristics of an
individual that influence survival and
reproduction
Lifespan
Atlantic Salmon
African elephant
House Mouse
60 - 70 years
3-6 years
2 years
22
How do the following life history traits affect
the rate of reproduction?
Age at maturity
offspring
reprod. events
life span
2 mo many one long 2 yr few many short 2
mo many many long 2 yr many many long
23
Reproductive strategies and population
fluctuations
  • K-strategists
  • long lived
  • produce few offspring
  • parental care

Remember that K is Carrying Capacity
24
Reproductive strategies and population
fluctuations
  • K-strategists
  • stable populations at carrying capacity (K)
  • examples humans (in theory), deer, lions
  • controlled by density-dependent limiting factors

factors more severe as population increases
example food
25
Reproductive strategies and population
fluctuations
  • r-strategists
  • small
  • short life
  • many offspring

Gypsy moth caterpillars
Remember that r is population growth rate
r b - d
26
Reproductive strategies and population
fluctuations
  • r-strategists
  • rarely reaches K
  • little or no parental care

Gypsy moth caterpillars
27
Reproductive strategies and population
fluctuations
  • r-strategists
  • controlled by density-independent limiting
    factors
  • weather, pond drying

Gypsy moth caterpillars
  • good at using temporarily abundant resources

28
Points to know Understand the three types of
survivorship curves. What factors influence
population growth rates? What are some life
history traits? Know the difference between K-
and r- strategists and what kind of limiting
factors each has.
29
Human Population Issues I
  • Lecture Objectives
  • Understand past and current human population
    growth trends and their impacts
  • Understand the factors that affect human
    population growth
  • Understand how social and political issues
    influence these factors

30
Human population growth
  • Long lag phase, then exponential growth

31
Currently
  • 6.2 billion humans on Earth
  • tripled since 1900 7.8 billion expected by 2025
  • Overall, 1.3 annual growth rate
  • 54 years to double population if not decreased

32
Currently
  • Countries vary greatly in actual growth rate

33
Why should we care about human population growth
rates?
  • Human population growth contributes to
  • Famine
  • Economic disparities increase, leading to
    increased political unrest
  • Environmental degradation
  • Water air pollution
  • Extinction of species
  • Carrying capacity of Earth???????

34
What factors influence human population growth?
  • Same as for other species
  • Birth rate
  • Death rate
  • Sex ratio
  • Age distribution
  • Immigration/emigration
  • Density
  • Study of these for humans called demography

35
Birth rates and Death rates
36
Sex Ratio
  • Humans have roughly 11 sex ratio
  • Total Fertility Rate number of children a woman
    has during lifetime
  • Replacement Fertility 2.1 children/female/lifeti
    me (leads to zero population growth in long term)

37
Age Distribution
  • If total fertility rate immediately 2.1,
    population would still increase for 20 years!

Aging population fewer young, productive workers
38
U.S. Age Distribution over time
  • Baby boom changes major societal concerns

University education, large young workforce
Housing, schools, supplies for children
Child care, luxury items, productive working
years
Retirement, elderly heath care
39
Immigration/Emigration
  • Of 1.1 increase in U.S. pop, 0.5 is due to
    immigration
  • Mexico loses an estimated 250,000 people per year
    to emigration
  • Millions of people want to emigrate from
    war-torn, poverty-stricken countries to more
    stable, developed countries

40
Population Density
  • Number of people per unit land area
  • As density increases, more severe impacts on
    environment
  • Density (people per sq mile)
  • India 733.2
  • China 320.9
  • US 68.7
  • Russia 22.7
  • not all square miles equally productive

41
Population Density
  • Distribution of people within countries also
    important.
  • 47 of worlds population in cities, expected to
    increase to 60 by 2025
  • Problems with dense populations in cities
  • Water transported long distances
  • Wastes difficult to get rid of
  • Decreased air quality
  • Large burden on local environment
  • Social unrest due to economic disparity

42
(No Transcript)
43
Social political factors influence human
population growth
  • What determines how many children a woman has?
  • What policies do countries have on population
    growth? Immigration?

44
Major social factors affecting birth rates
  • 1. Cultural role/status of women
  • In male-dominated societies, traditional role of
    women is to marry have children
  • Women not educated, encouraged to marry young
  • Lack of education makes women dependent on
    husband, children
  • Women in developed countries educated, have
    option to delay marriage or not marry

45
Major social factors affecting birth rates
  • 1. Cultural role/status of women, cont.
  • Early marriage more child-bearing years more
    children
  • of births by 15-19 year olds
  • Africa 17
  • Latin America 16
  • All developed countries 3

46
Major social factors affecting birth rates
  • 2. Desires of women access to birth control
  • Women in less-developed countries have more
    children than they want
  • Often little access to birth control, education
    on how to use
  • Religious views on birth control
    (http//www.cnn.com/2004/LAW/03/01/church.contrace
    ptives.ap/index.html)
  • However, women in less-developed countries want
    more children than women in developed countries.
  • WHY?

47
Economic value of children
  • In less-developed countries
  • Guard against high infant mortality
  • Security in old age
  • Labor force
  • desire for more children
  • In developed countries
  • High probability of survival
  • Large economic expenditure not put into
    retirement plan
  • Increase labor by parents
  • desire for less children

48
Most important factors affecting population
growth rates
  1. Development of/access to modern birth control
  2. Education of women

49
Political policies on population growth
  • Encouraged in some countries (U.S., European) by
    subsidies
  • Paid maternity leave
  • Guaranteed jobs
  • Childcare
  • Tax deductions
  • Birth bonus (Canada)
  • Need younger workers to support aging populations

50
Political policies on population growth
  • Discouraged in other countries with varying
    degrees of success
  • China
  • 1. Due to slow economic growth, PRC began first
    population control measures in 1955
  • 2. Campaign begun in 1971
  • - Raised legal age of marriage to 23 for women,
    25 for men in rural areas and 25,28 in urban
    areas
  • 3. One child limit started in 1978
  • 4. Contraception and abortion readily available
    and widely used.
  • Result Current total fertility rate of 1.8

51
Political policies on population growth
  • India
  • 1. Little government intervention until recently
  • 2. Emphasizing improving quality of life
  • - Decrease infant mortality to decrease desire
  • - Encourage education for women
  • Result Current total fertility rate of 3.2
    children (goal of 2.1 by 2010)

52
Effect of different policies
  • Pop size (mil) growth rate added/year
    (mil)
  • China 1280.7 0.7 8.96
  • India 1049.5 1.7 17.84
  • This is not an endorsement of the methods used by
    PRC to reduce births!!

53
Political policies on immigration
  • Countries with low birth rates (European, Japan,
    China) may face shortage of workers without
    immigration
  • Emigrants want to move to developed countries to
    improve standard of living
  • Tremendous pressure on Europe and N. America to
    accept immigrants
  • Significant numbers of immigrants can strain
    social systems

54
How many total children do you want to have?
  • 1) 0-1
  • 2) 2-3
  • 3) 4-5
  • 4) gt 5

55
Points to know
  1. Know the past, present, and projected future
    world population of humans
  2. Know the human issues for each of the 6 factors
    that affect population growth rate
  3. Why do women have more children in male-dominated
    societies and less children in developed
    countries?
  4. What two changes have caused/will cause the
    greatest decrease in population growth rates?
  5. How have political policies in China and India
    changed their population growth rates?
  6. How do political policies on immigration affect
    growth rates? Why do many people want to emigrate?
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