1. Population Biology

2. Population Growth J-Curve Exponential Growth Unchecked growth
As a population gets larger it grows faster

3. Population Growth S-Curve Carrying capacity
Number of organisms the environment can support
Limiting factors
Biotic
abiotic

5. Patterns Reproductive pattern = life-history pattern
Variety of patterns
Two extremes

6. Patterns Rapid life-history patterns
Changing or unpredictable environment
Small
Mature rapidly
Reproduce early
Short life span

7. Patterns Slow life-history pattern Large species Stable environments
Reproduce slowly
Matures slowly
Long life span
Stay at or near carrying capacity

8. Clumped Random Uniform Population Density Dispersal patterns Random

9. Population Density Density-dependent factors
Disease
Competition
Predators
Parasites
food
Density-independent factors
Volcanoes
Temperature
Storms
Floods
Drought
Habitat disruption

10. Other population factors
Predation
Competition

11. Age Structures and Human Growth
Human Populations
Age Structures
and
Human Growth

12. Populations Populations—large and small—change over time
Meaning, they are DYNAMIC
Humans face similar problems as small or large populations that other organisms do

13. Factors That Influence Population Size
Population growth rate
Determined by:
Natality or birth rate
Death rate
Also influenced by immigration and emigration.
Expressed mathematically:
r = (b-d) + (i-e)

14. When Studying Populations…
Straight forward expression of population size is absolute number.
Count up all the individuals in the population.
More frequently used is density.
The number of individuals per unit area.

15. Labs… Random Sampling
A method of selecting a sample (random sample) from a statistical population in such a way that every possible sample that could be selected has a predetermined probability of being selected
BEST for STATIONARY POP (pic of or plants!!!)

16. Mark and Recapture
A method of sampling an animal population where animals are caught alive and tagged and then returned (unharmed) to their habitat
over time animals from the pop are trapped and those with marks/tags are counted
a mathematical formula estimates the pop size

17. Fish/Eagle What was the purpose of this lab? What happened when…
Competition with Osprey
Drought decreases the fish population
Fish spawn and double their population
Pollution decrease the fish population by ¾
Eagle’s have two offspring
So what does this say about the eagle’s diet?

18. Population Stress
As populations increase in size in environments that cannot support increased numbers, individual animals can exhibit a variety of stress symptoms.
These include aggression, decrease in parental care, decreased fertility, and decreased resistance to disease.
They become limiting factors for growth and keep populations below carrying capacity.

19.  Self Check  A. population increases exponentially
Characteristics of Population Growth
Exponential growth
J curve
S curve
Population
Time
Carrying capacity
Which of the following would you expect to observe after a population exceeds its carrying capacity?
A. population increases exponentially
B. births exceed deaths
C. deaths exceed births
D. population growth rate is unaffected by limiting factors
The answer is C.

20. Age Structure
A population’s age structure indicates the percentage of individuals at each age.
The right side shows females; the left, males
The x-axis numbers are populations size
Usually in millions
The y-axis is age ranges usually 0-4, 5-9, 10-14, etc…

23. US Dynamic Age Structure

24. Ya’ll me

25. Population Size Problems being a Large population
Increase food shortages & diseases
Decrease in space, clean water
Live at carrying capacity so can experience huge crash
Adaptable with greater genetic diversity
Perils of Small Populations
low genetic diversity
subject to inbreeding
less likely to adapt to environmental changes

26. History of Human Population Growth
The Development of Agriculture
About 10,000 to 12,000 years ago, the development of agriculture increased the growth rate of the human population.

27. What happened in the 1600s? The Population Explosion
Around 1650, improvements in hygiene, diet, and economic conditions further accelerated population growth.
After World War II, the human population grew at the fastest rate in history, largely because of better sanitation and medical care in poorer countries.

28. Advances in Human Technology = Growth

30. Demographic Transition
Human populations have undergone rapid growth, yet in some developed countries, populations have stopped growing.
The demographic transition model shows how these population changes happen.