1. Announcements
Lichen Lab is due next week

2. Examples of Logistic Growth
Ex. fur seal population, St. Paul Island, AK
Ex. Paramecium

3. The maximum number of individuals the environment can support is called
Density determinant
Carrying Capacity
Saturation
Maximum limit

4. Why do these populations level off as opposed to experiencing exponential growth?
Limits of the environment – food, water, space etc

5. Three patterns of population growth: Exponential Logistic Overshoot
Oscillations
Crash and Burn
Models – ‘ideal’

6. Overshoot with Oscillations
Growth is so rapid the pop exceeds K
Pop declines and recovers
Cycles around K
Ex. Moose on Isle Royale in Lake Superior

7. Overshoot with Crash & Burn
Often occurs when a pop experiencing exponential growth runs out of resources
Ex. Caribou on St. Matthew's Island

8. Ex. Caribou on St. Matthew's Island
29 introduced in 1944
1980 Extinct
For a sense of how fast they grew
1944: 29 indivs. arrive
1956: pop size = 1,350
1963: pop size = 6,000
1966: pop size = 44
1980 Extinct

9. Reproductive Strategies
r-selected species
K-selected species
What does the names tell us about how they might reproduce?

10. r-selected species Grow very rapidly Named due to high r
Massive # of offspring
Little to no parenting
Short life span
Small size

11. K-selected species More likely for pop to be close to K
Fewer offspring
Care for young
Longer lived
Larger size

12. B. History of Human Population Growth

13. 6.87 billion people
1800s – 1 billion people

14. What type of growth does the prior graph show?
Explosive
Exponential
Logistic
Chaotic

15. The # of people the earth can support depends on
(K)
Technology
Resource use
Earth’s productivity
Ex. More food from land

16. History of Human Population Growth
Hunter-gatherers
Agricultural Revolution
Industrial Revolution

17. Hunter-gatherer Society
Existed for most of human history
World pop = a few million
People move in search of food

18. People move in search of food
No permanent shelter
Low birth rate, low death rate → Stable pop. size

19. Agricultural Revolution
10,000 yrs ago people began growing crops
People stay in one place and have larger families
b increases

20. People stay in one place and have larger families
b increases
More food and better shelter
d decreases
Still diseases and sanitation problems
Population increases

21. Population increases

22. Industrial Societies
Industrial Revolution – 200 yrs ago
Death rate decreases
Birth rate decreases

23. Death rate decreases
Technology: Medicine, sanitation, agriculture

24. Birth rate decreases
High birth rate → low birth rate
Doesn’t occur immediately

25. Initially, population increases rapidly
and then becomes stable