1. Chapter 5 Populations Section 5.1 How Populations Grow
Section 5.2 Limits to Growth
Section 5.3 Human Population Growth

2. Section 4.1 Population Dynamics
Compare
&
contrast
exponential and linear
population growth.
Relate
the reproductive patterns of different populations of organisms to models of population growth.
Predict
effects of environmental factors on population growth

3. What is a Population?
One species spread over it geographic range (all areas it lives)
Density # in population within the geographic range
3 types:
Random
Uniform
Clumped

4. Population Growth Growth Rate is effected by several factors:
Age Structure number of males/females and their ages
Birthrate number of babies born a year
Death rate number of deaths a year
Immigration members entering the range
Emigration members leaving the area

5. Types of Population Growth
J-shape growth
Exponential Growth:
As a population gets larger, it also grows at a faster rate
Always the growth rate after a succession or a new species is introduced

6. Type of Population Growth
S-shape growth
Logistic Growth:
After exponential growth slows down as resources become limited
Growth flattens out at maximum possible population size (carrying capacity)

7. Limits to Growth Carrying capacity
The number of organisms of one species that an environment can support indefinitely is its carrying capacity
When a population overshoots the carrying capacity, then limiting factors may come into effect

8. Limits to Growth
Limiting Factor any factor that limits a populations size
Food, predators, space, water, etc..
2 Types:
Density-Dependent
Increase/decrease with population’s size
Density-Independent
Size of population has no affect

9. Density-Dependent Limiting Factors
Competition
More members the more food/water that is required
Kills off weaker members
Predation
Prey and Predator numbers are effected by each other
Overcrowding
Stress of crowds weakens immune systems and increases fighting
Parasitism and Disease
Overcrowding spreads disease faster

10. Density-Independent Limiting Factors
Weather Patterns
Ruin food supply
Run out of fresh water
Limit time to hunt/reproduce
Natural Disasters
Massive lowering of population numbers
Change the ecosystem
Remove important food supply

14. Human Population Growth
Human’s used to have a very high birthrate but also a very high death rate
Today the birthrate is 4 babies a second but the death rate is much lower
What factors lowered our death rate?
Food supply, medicine, civilization, etc…

15. Demographic Transition
Demography study of human populations
Periods of Growth:
High birth and death rates in unstable environments
Lowering of death rates as environment becomes more stable
Birthrates fall to meet death rates as resources become limited

16. Age Structure’s Effects on Growth
Populations with high numbers teens and young adults will lead to fast massive growth
Large number in the older generation will have slower growth
Most stable growth is having near even numbers in all age groups

17. Homework! Read Ch. 6; You have another presentation coming up
Ch. 6 vocabulary
Ch. 5 “Apply Vocab” and questions #1-16 on p