1. Population Ecology
Chapter 39 – Certain ecological prinicples govern ALL populations
Basic ecological principles govern the growth and sustainability of all populations

2. Population Characteristics (Demographics)
Population Size
Population Density
Population Distribution
POPULATION SIZE = Number of individuals that contribute to population’s gene pool within the same geographic area
Age Structure = number of individuals
in age categories
Pre-reproductive, reproductive,
post-reproductive
Reproductive Base
Demographics = “vital statistics”
Birth rate vs. Death rate
Immigration vs. emigration

3. Population Density Number of individuals per specified area or habitat
2011 World Population density (individuals per square km)

4. Population Distribution
General pattern in which individuals are distributed
Covers 39.2
Clumping is MOST COMMON, due to ???
environmental conditions
behavioral issues
reproductive concerns
Random Sampling
Capture/
recapture

5. Population Growth Immigration Emigration Migration Birth/death rate
With NO limiting factors
J-Shaped curve = exponential curve
39.3
Doubling Time
Biotic Potential

6. Population Growth Limits
Reality
Limiting Factors
Short supply of any essential resource = ?
Carrying capacity
Maximum number of individuals that an environment can sustain
NATURAL SELECTION?
S-shaped curve = logistic curve

8. Typical population growth

9. Limiting Factors
In nature, most populations are never able to reach biotic potential
Density-dependent
Biotic factors
Predator
Parasitism
Competition
39.4 Limits
Density-independent
Abiotic factors
Weather
Elevation

10. Typical biotic carrying capacity relationship

11. World Population Growth
What differentiates humans from other species found in nature?
How does this impact population growth?
Skip 39.5& 39.6, this is 39.7

12. Doubling Time
The rate of national population growth is expressed as a percentage for each country, commonly between about 0.1% and 3% annually. You'll find two percentages associated with population - natural growth and overall growth. Natural growth represents the births and deaths in a country's population and does not take into account migration. The overall growth rate takes migration into account.
In the U.S., the natural growth rate is 0.6% and overall growth is 0.9%. The growth rate of a country provides demographers and geographers with a good contemporary variable for current growth and for comparison between countries or regions. For most purposes, the overall growth rate is the more frequently utilized.
The world's current growth rate is about 1.3%, representing a doubling time of 54 years. We can expect the world's population of approximately 6 billion (2000) to become 12 billion by 2054 if the current rate of growth continues. The world's growth rate peaked in the 1960s at 2% and a doubling time of 35 years.

13. World Population Distribution by Region, 1800–2050

14. Age Structure Diagrams
Fertility Rate
Replacement Levels
Rapid Growth
High pre-reproductive and productive population
Slow Growth
Steady declining population with age
Zero Growth
Equal distribution of ages
Negative Growth
Low pre-reproductive and productive population
39.8

16. Demographic Transition
Relates economic conditions to population growth
Stages:
Pre-Industrial
High birth & death rates
Transitional
Declining death rates
Industrial
Declining birth rates
Post-Industrial
Low birth & death rates