1. Understanding Population Growth
Ch 52
No more for you mrs. Willie!!
Understanding Population Growth

3. Organism

4. POPULATION POPULATION

5. Community

6. Ecosystem

7. Population Ecology Deals with #’s of indiv. in a species
How and why their numbers are the way they are

8. A better way to describe size of a pop. Manhattan, New York City
Population Density
# of indiv. of a species
unit of area
A better way to describe size of a pop.
Manhattan, New York City
70,595 people per sq. mile

9. Dhaka, Bangladesh: 7 million in 59 mi2

13. Lack of Natural Resources
Crowded Much?!?
Competition
Spread of Disease
Lack of Natural Resources
Lack of Jobs

14. Populations Change in Size…
Births, deaths, immigrants, and emigrants

16. Question: How can you get the growth rate of a population to slow down
Question: How can you get the growth rate of a population to slow down? Give reasonable solutions! Make a list with your partner 

17. Reproductive Strategies

18. Exponential Growth= r-selected
AKA J Curve

19. Occurs when Pops Doubling OverTime

20. Practice: With a 2 % growth rate, the world population will double….
Doubling Time
Time for a pop. w/ a stable growth rate to double in size
Doubling Time =
td = 70
r (%)
Practice: With a 2 % growth rate, the
world population will double….

21. R-selected Species Many small offspring Little/no care of offspring
Most offspring die before reaching reproductive age
High population growth rate
Generalists

22. Logistic Growth: K-selected
AKA S Curve

23. Carrying Capacity
K = carrying capacity (Max. pop. of a particular species that a habitat can support over a given time period.

24. Carrying Capacity Seasons Changes in environment (fire, storm, etc.)
May vary by:
Seasons
Changes in environment (fire, storm, etc.)

25. K-selected Species
Fewer, larger offspring
High parental care
Most offspring reach reproductive age
Lower population growth rate
Specialists

26. Density-Dependent Factors
Increasing pop size leads to less available resources  limiting pop growth
DD factors: competition, predation, disease, poisoning…all increase when pops grow w/in limited space.

27. Density-Independent Factors
Limits placed on pop growth (not due to space issues)
Ex: Natural disasters or Severe weather

28. Survivorship Proportion of a pop. to survive to breeding age
Type I= Late loss: K-strategists.
Type II = Constant loss: intermediate reproductive strategists
Type III = Early loss: R-strategists