1. Population Ecology and Human Population Issues

2. population
a group of individuals of the same species living in a certain area

3. Factors Affecting Populations
natality – the number of individuals added to a population through reproduction
mortality – the number of deaths in a population over time

4. sex ratio – the relative numbers of males and females
age distribution – the number of individuals in each age group
pre-reproductive
reproductive
post-reproductive

5. Population Density and Spatial Distribution
population density – the # of organisms per unit area
dispersal – movement away from densely populated areas
immigration – movement in to an area
emigration – movement out of an area

6. Population Growth
biotic potential – how fast a species can increase its population if no limiting factors exist
recruitment – the percent of a population that lives long enough to reproduce

7. Reproductive Strategies in Nature
r-strategists – organisms with high biotic potential but low recruitment – small, fast-growing, short-lived
K-strategists – organisms with low biotic potential but high recruitment – large, longer lifespan

8. Estimating Population in the Wild
sampling- counting the population in a small area and projecting that density over the entire area
mark and recapture- capturing, tagging, releasing, and recapturing a segment of a mobile population

9. Assumptions for validity of mark and recapture techniques
tagging does not change the behavior of the animal
tagged animals must have time to freely mix with the rest of the population
animals must be captured randomly

10. Population Growth
exponential growth – growth at an ever-increasing rate

11. Population Growth
logistic growth – growth with limits

12. Limits to Growth
carrying capacity – the maximum size of a population that can be supported over the long term
environmental resistance – abiotic and biotic factors that tend to reduce populations

13. Demography
the study of human population growth and its consequences

14. Human Population Growth
why was human population growth relatively stable for 50,000 years (until the early 1800’s)
why has the population explosion occurred?
when will our population stabilize?
what is the planet’s carrying capacity for humans?

15. Survival Rates
longevity- the maximum age of death of a population – biologically determined
life expectancy- the average age of death – mathematically determined
survival rates- the % of a population living past a certain age

16. the two most important historical/scientific events that lead to the human population explosion
1800’s – after the discovery of bacteria, connections were made between sanitation, personal hygiene, and disease
1930’s - antibiotics

17. Why is human population growth an environmental issue?

18. rapid population growth leads to … environmental stress
Major Global
Environmental Issues
water pollution, water shortages
atmospheric change (air pollution, global warming, ozone loss, acid rain)
soil degradation (erosion and loss of fertility)
loss of biodiversity (extinctions)

19. Industrialization
developed countries – fully industrialized, modern, high GDP
developing countries – various stages of modernization, lower GDP

20. where population growth is occurring
95 % of population growth today is occurring in developing countries

21. demographic statistics
total fertility rate – the average # of children a woman has in her lifetime
infant mortality rate – the part of a population that dies before age one
replacement fertility rate – the fertility rate that will yield a stable population (2.1)
age distribution – the number of people in each age bracket

22. changing populations crude birth rate (CBR) – # of births/1000 people
crude death rate (CDR) – # of deaths/1000 people
population growth rate % = CBR – CDR/10
doubling time: the # of years it takes for a population to double
rule of 70: doubling time = 70/pop growth rate

23. social factors affecting population growth …
historically high infant mortality combined with lack of social security in old age
child labor needs for rural lifestyle
lack of education/work opportunity for women
cost of child raising in urban lifestyle

24. political factors affecting population growth …
China one child policy
incentives/disincentives for having children

25. why is it desirable to control human population growth?
many humans live in poverty
all environmental problems made worse with increasing population
running out of resources
other species

26. What are some arguments against controlling human population growth?
more people, more ideas, creativity, technology
birth control is immoral
it’s not population, it’s consumption
population will level off naturally within Earth’s carrying capacity
population control is “social engineering”

27. two schools of thought regarding the population problem
control population through biological means
encourage development in poor countries where population is growing the fastest

28. demographic transition theory
as a country industrializes, it goes through a series of changes leading to a stable population

29. stages of the demographic transition
stage I - high CBR, high CDR … stable population
stage II - high CBR, lowering CDR … rapid growth
stage III - with increased industrialization, CBR begins to lower
stage IV - full industrialization, low CDR, low CBR … stable population

30. Demographic Transition Theory

31. Encouraging development
world bank lending – U.N. lending large sums of $$ to governments
microlending – small banks lending small amounts of $$ to individuals

32. Why the shift?
many World Bank projects (agriculture and energy) were mishandled by inept and/or corrupt governments resulting in increased debt for developing countries and little improvement in standard of living
micro-loans have a 98% payback and have resulted in progress for individuals

33. Predicting Future Population Growth
population profile – a model showing relative age distribution of a population in five-year increments

34. Profiles
what would a rapidly growing country’s population profile look like?
what would the population profile look like for a country whose population is stable?
what would the population profile look like for a country whose population is declining with each new generation?

37. ecological footprint
The amount of biologically productive land necessary to support your lifestyle
what goes into this measurement?

38. Per Capita Ecological Footprint Total Ecological Footprint
(Hectares per person)
Country
United States
The Netherlands
India
9.6
3.8
0.8
Total Ecological Footprint
(Hectares)
Country
United States
The Netherlands
India
3 billion
hectares
62 million hectares
880 million
hectares
Fig. 1-7a, p. 11

39. Ecological Footprint Fig. 1-7b, p. 11 1.5 Earth's Ecological Capacity
1.2
0.9
Humanity's Ecological Footprint
Number of Earths
0.6
0.3
1960
1970
1980
1990
2000
2010
Year
Fig. 1-7b, p. 11