1. Section 5-1 Characteristics of Populations
Flora

2. 3 important Characteristics of Populations
Geographic distribution – describes area inhabited by a population
Density
# of organisms per unit of area
# often varies from population to population
Growth rate
Age structure(will be discussed later)

3. Population Growth 3 factors that affect population size # of births
# of deaths
# of individuals that enter or leave a population
* Populations grow when birth rates exceed death rates

4. Population Growth Cont.
Immigration – movement of individuals into an area
Emigration – movement of individuals out of an area

5. Exponential Growth
Usually depends on having abundant space and food; lacking disease and predators
Exponential growth – occurs when the individuals in a population produce at a constant rate
Exponential growth does not continue in natural populations for an extended period of time
Represented by “J” shaped curve
See figure 5-3; page 121

6. Logistic Growth
As resources become less available, the growth of a population slows or stops
Logistic growth – occurs when a population’s growth slows or stops following exponential growth
Represented by “S-shaped” curve
Figure 5-4; page 122

7. Carrying Capacity
Carrying Capacity – the largest # of individuals that an environment can support
Populations reach carrying capacity when resources become less available
See figure 5-4; page 122