1. Topic 4: Population Biology
Unit: Ecology
Topic 4: Population Biology

2. Population Growth
Exponential Growth – as a population gets larger, it grows faster
J-shaped curve on a graph
Results in population explosion!

3. B. Carrying Capacity
The number of organisms of one species that an environment can support over a long period of time
Over – deaths exceed births until population again under carrying capacity
Under – births exceed deaths

4. C. Population Patterns
Determined by reproductive pattern (AKA life-history pattern), and related to environmental conditions
Rapid life-history – small body size, rapid reproduction, short lives, little parental care; unstable environmental conditions

5. C. Population Patterns
Slow life-history – large body size, slow reproduction, long lives, much parental care;
stable environmental conditions

6. Limits to Population Size
Density Dependent
Predation
Numbers of predators and prey cycle
Important for health of populations
old and injured caught
improves odds of enough resources for healthiest
Competition
food, water, space, etc.

7. Limits to Population Size
3. Disease
Communicable disease rate increases with density
Examples: AIDS, flu, Tuberculosis, Dutch Elm Disease, Pfiesteria

8. Limits to population size
Parasitism
Parasites are host specific
Crowding helps parasite move from one host to another
Crowding & Stress
May affect hormones (reproduction rates), immune system and aggression
Fleas

9. Limits to Population Size
Density Independent
Weather – most important
Human activities – toxic waste, pesticide, etc.

10. Human Population Growth
Demography – study of human population growth characteristics
Human population has increased exponentially over the past several hundred years!

11. Human Population Growth
Birth and death rates vary by stage country is in
Age Structure

12. Human Population Growth
Mobility
Immigration – movement of individuals into a population
Emigration – movement of individuals out of a population