1. Chapter 8 Population Change

2. Overview of Chapter 8 Principles of Population Ecology
Reproductive Strategies
The Human Population
Demographics of Countries
Demographics of United States

3. Principles of Population Ecology
Study of populations and why their numbers change over time
Important for
Endangered species
Invasive species
Population
Group of individuals of same species living in the same geographic area at the same time

4. Population Density Population density
The number of individuals of a species per unit area or volume at a given time
Ex: minnows per Liter of pond water
Ovals below have same population, and different densities

5. Change in Population Size

6. Change in Population Size

7. Calculating Population Change
Birth (b), Death (d), Immigration (i) and Emigration (e) are calculated per 1000 people
Death rate
Growth rate
Emigration rate
r = (b – d) + (i – e)
Birth rate
Immigration rate

8. Maximum Population Growth
Intrinsic Rate of Growth (Biotic Potential)
Growth rate under ideal conditions
J- Shaped Curve (exponential growth)

9. Environmental Resistance
Environmental limits (resistance)
Prevent indefinite reproduction
Unfavorable food, water, shelter, predation, etc.
Carrying Capacity (K)
Maximum # of individuals an environment can support
Causes leveling off of exponential growth
S- shaped curve of logistic population growth

11. Population Crash
Overshooting carrying capacity can lead to population crash
Abrupt decline in population density

12. Factors That Affect Population Size
Density Dependent Factor
Factor whose effect on population changes as population density changes
Examples:
Predation
Disease
Competition
Sometimes cause Boom-or-Bust Population Cycles

13. Boom-Or-Bust Population Cycles

14. Case Study- Predator Prey Dynamics on Isle Royale
As wolf population increases, moose population decreases (and vice versa)

15. Factors That Affect Population Size
Density Independent Factors
Factors that affects population size, but is not influenced by changes in population density
Examples:
Killing frost
Severe blizzard
Fire

16. Reproductive Strategies
r-selected species
k-selected species
-Small body size
- Early maturity
- Short life span
- Large broods
- Little or no parental care
Probability of long term survival is low
Mosquitoes and Dandelions
Small broods
Long life span
Slow development
Large body size
Late reproduction
Low reproductive rate
Redwood trees and human beings

17. Survivorship

18. Some populations fit two curves
Herring Gulls
Type III & Type II

19. Human Population Demography
Science of population structure and growth
Human Population since 1980 is J-shaped curve

20. Human Population In 2011, world population increased to 7 billion
1800
2 Billion
1930
3 Billion
1960
4 Billion
1975
5 Billion
1987
6 Billion
1999
6.6 Billion
2006
In 2011, world population increased to 7 billion

21. Population Increase in Mexico

22. Projecting Future Populations
Population is increasing
Growth rate (r) has started to decline
Projections for 2050
Low = 7.7 billion
High = 10.6 billion
Most likely = 9.1 billion

23. Demographics of Countries

24. Demographic Stages Pre-industrial Stage Transitional Stage
Birth and death rates high
Modest population growth
Transitional Stage
Lowered death rate
Rapid population growth
Industrial Stage
Birth rate decline
Population growth slow
Post Industrial Stage
Low birth and death rates
Population growth very slow

25. Demographic Stages

27. Age Structure
The number and proportion of people at each age in a population

28. Demographics of Specific Countries

29. World-wide 29% of human population is under age 15
Could cause large increase in birth rates

30. Education of Immigrants into US