1. What Are the Factors That Can Affect Various Populations?

2. Population Density
It is the number of organisms living in a given space.
There are four factors that affect the growth (or reduction) of a population

3. Can this happen in nature?
Yes
Invasive species
Uniform habitat
No predators
No disease
Unlimited area
Can this happen?
70 miles a year
No constraints

4. Invasive species
An invasive species is one that can be either native and non-native that heavily colonize a particular habitat.
Natural, wild species can be threatened with extinction.

5. The good ones
Asian Oysters- are better at filtering out water pollutants than native oysters.
Garlic Mustard- introduced as a means of erosion control

6. The bad ones
Zebra mussles
Waterlettuce is a serious weed
of rice crops
Burmese python

7. #1 ~ Births
This is the number of surviving offspring

8. #2 ~ Deaths Number of individuals dying from all causes.
limited food supply
the buildup of toxic wastes
increased disease
predation

9. #3 ~ Immigration #4 ~ Emigration
Number of individuals entering an area.
#4 ~ Emigration
Number of organisms leaving an area.

10. What Can Affect Each of These Factors?
Climate, Food Availability, Living Space, and Disease can affect each of these factors.

11. Carrying Capacity
The population remains within the limits that the environment can support
This is the largest amount of species that an environment can support
There are four factors that can influence Carrying Capacity (K).

12. A ~ Materials / Energy Food, water, and other essentials.
If a population continues to grow, it will eventually exceed its food supply (starvation, malnutrition).

13. B ~ Food Chains
Populations are limited by organisms above them.

14. C ~ Competition
For food, space, mates, and water.

15. D ~ Density
There are two types of Density that can affect carrying capacity.
Density-independent factors
Weather (storms, cold, drought)
Density-independent diseases (DDT poisoning)
Density-dependent factors
Food
Space (territories, denning sites, nest cavities)
Density-dependent diseases (rabies, SARS)

16. Logistic growth is slowed by population-limiting factors http://www
Logistic growth is slowed by population-limiting factors applet

17. K Maximum sustainable yield Maximum sustained yield Population size
Carrying capacity
r = intrinsic rate of increase. B-D. R=1+r
Time, in generations

18. The Spread of Shakespeare's Starlings
In 1890, a group of Shakespeare enthusiasts released about 120 starlings in New York's Central Park

19. Today: over 100 million starlings, spread over N. America
Current
1955
Current
1955
1945
1935
1925
1945
1905
1915
1925
1935
1925
1935

20. The starling population in North America has some features in common with the global human population
Both are expanding and are virtually uncontrolled
Both are harming other species

21. THE HUMAN POPULATION doubled three times in the last three centuries
about 6.1 billion and may reach 9.3 billion by the year 2050
improved health and technology have lowered death rates

22. The history of human population growth
Figure 35.8A

23. Also reveals social conditions, status of women
The age structure of a population is the proportion of individuals in different age-groups
RAPID GROWTH
SLOW GROWTH
ZERO GROWTH/DECREASE
Kenya
United States
Italy
Male
Female
Male
Female
Male
Female
Ages 45+
Ages 45+
Ages 15–44
Ages 15–44
Under 15
Under 15
Percent of population
Percent of population
Percent of population
Also reveals social conditions, status of women

24. The ecological footprint represents the amount of productive land needed to support a nation’s resource needs
The ecological capacity of the world may already be smaller than its ecological footprint

25. Ecological footprint in relation to ecological capacity

26. What next?