1. Population Dynamics

2. Populations
A population is a group of organisms of the same species that live in a particular place at one time.
A population could be a species of plants, animals, bacteria, or people, living in a given area (for example, bass living in an isolated pond).

3. Population Dynamics:
Populations are constantly changing and we need to keep up with the changes. The study of human population is demography. Some measures are:
Birth Rate – Number of births in a given time. (U.S. – 4 million per year)
Death Rate – Number of deaths in a given time. (U.S. – 2.4 million per year)
Life Expectancy – how long the avg. person lives. (U.S. men – 77, women – 80)

4. Age Structure Diagrams
Distribution of people of different ages (shown: histogram)
Also Shows Sex Ratio – number of males to females.

5. Other histograms:

6. Population Growth Rate
Amount by which a pop. changes over a period of time, depends on 4 processes: birth rate, death rate, immigration, and emigration.
BR + immigration - DR + emigration = growth
Growth of a population is usually exponential, only contained by limiting factors (food, water, space,density…)

7. Exponential Growth – J-shaped curve. Unlimited growth ex. Humans

8. Logistic Growth – S-shaped curve
Logistic Growth – S-shaped curve. Pop’s growth slows because of a limiting factor (at carrying capacity) ex. Rabbits in the wild

9. Exponential and Logistical Growth Graph

10. Density Factors
Density-independent – affect all populations in similar ways regardless of size. Fires, deforestation, dams, floods, hurricanes etc…
Density-dependent factors – a limiting factor that depends on the size of a population. The more crowded = more competition, predation, parasitism, and disease. CYCLIC