1. Ch. 53 Warm-Up
(Review) Sketch an exponential population growth curve and a logistic population growth curve.
What is an ecological footprint?
What are ways that you can reduce your ecological footprint?
Define:
Demography
Semelparity
Iteroparity
Carrying capacity
Exponential growth curve
Logistic growth curve
K-selection
r-selection
Ecological footprint

2. Chapter 53
Population Ecology

3. Introduction
Population = group of individuals of a single species living in same general area
Density: # individuals / area
Dispersion: pattern of spacing between individuals

4. Determining population size and density:
Count every individual
Random sampling
Mark-recapture method

5. Patterns of Dispersal:
Clumped – most common; near required resource
Uniform – usually antagonistic interactions
Random – not common in nature

6. Demography: the study of vital statistics that affect population size
Additions occur through birth, and subtractions occur through death.
Life table : age-specific summary of the survival pattern of a population
Represent data with a survivorship curve.
Plot # of individuals in a cohort still alive at each age.

7. Life Table

8. Survivorship Curves:
Type I curve: low death rate early in life (humans)
Type II curve: constant death rate over lifespan (squirrels)
Type III curve: high death rate early in life (oysters)

9. Life History: traits that affect an organism’s schedule of reproduction and survival
3 Variables:
Age of sexual maturation
How often organism reproduces
# offspring during each event
Note: These traits are evolutionary outcomes, not conscious decisions by organisms

10. Semelparity Big-bang reproduction Many offspring produced at once
Individual often dies afterwards
Less stable environments
Agave Plant

11. Iteroparity Repeated reproduction Few, but large offspring
More stable environments
Lizard
Critical factors: survival rate of offspring and repeated reproduction when resources are limited

12. Change in Population Size
N/t = B-D
N = population size
t = time
Change in population size during time interval
Births during time interval
Deaths during time interval = -

13. Zero population growth: B = D
Exponential population growth: ideal conditions, population grows rapidly

15. Unlimited resources are rare
Logistic model: incorporates carrying capacity (K)
K = maximum stable population which can be sustained by environment
dN/dt = rmax((K-N)/K)
S-shaped curve

16. Laboratory Populations

17. Factors that limit population growth:
Density-Dependent factors: population matters
i.e. Predation, disease, competition, territoriality, waste accumulation, physiological factors
Density-Independent factors: population not a factor
i.e. Natural disasters: fire, flood, weather

18. K-selection r-selection
K-selection: pop. close to carrying capacity
r-selection: maximize reproductive success
K-selection
r-selection
Live around K
Exponential growth
High prenatal care
Little or no care
Low birth numbers
High birth numbers
Good survival of young
Poor survival of young
Density-dependent
Density independent
ie. Humans
ie. cockroaches

19. Populations fluctuate due to biotic and abiotic factors
: peak in wolf numbers
1995: harsh winter weather (deep snow)

20. What do you notice about the population cycles of the showshoe hare and lynx?

21. Boom-and-bust cycles Predator-prey interactions
Eg. lynx and snowshoe hare on 10-year cycle

22. Human Population Growth
2 configurations for a stable human population (zero population growth):
High birth / high death
Low birth / low death
Demographic transition: occurs when population goes from A  B

23. Age-Structure Diagrams

24. Global Carrying Capacity
UN predicts: 7.8 to 10.8 billion people by the year 2050
2012 = 7 billion
Estimated carrying capacity = billion?
Ecological footprint: total land + water area needed for all the resources a person consumes in a pop.
1.7 hectares (ha)/person is sustainable
U.S.: 10 ha/person  over K??
Limitations? Consequences? Solutions?

26. Map of ecological footprint of countries in the world (proportional sizes shown)