1. MEASURING POPULATIONSpp

2. birth rate: # of births occurring in a given amount of time
death rate: # of deaths occurring in a given amount of time

3. GROWTH RATE
The amount a population size changes in a given time

4. GROWTH RATE net reproduction r = birth rate – death rate
Growth rate= r = b - d

5. EXAMPLE of per capita rate
In a rat cage containing 400 rats, 100 rats are born and 40 die.
P.C. Growth rate= p.c.r = (b – d) / total population
p. c. r= #of births - #of deaths
total population
p.c.r= = 60 = 0.15

6. What the per capita means
If the value is +, the population is growing
If the value is -, the population is declining
You can estimate the next year’s population size
EX x 400 = 60
original population + change = new pop.
= 460
How big would the population be the next generation?

7. BACK TO MODELS
POPULATION GROWTH: # of births is greater than the # of deaths
ZERO POPULATION GROWTH:
# of births is equal to # of deaths (G = 0)

8. EXPONENTIAL MODEL:
exponential rate increase
birth and death rates are constant (b > d)
limited by density-independent factors

9. LOGISTIC MODEL:
starts off as b> d
levels off as it reaches carrying capacity K
This is when b = d rates (zero population growth)
limited by density-dependent factors

10. REGULATING POPULATION SIZE AND GROWTH
Carrying Capacity: The population has reached its limit of density dependent factors and achieves zero population growth.
Limiting factors: restrains population growth
Density-independent factors: no regard for population density
EX. Weather, seasons, natural disasters
Density-dependent factors: increase or become more prominent when the population density increases
EX. predation, pollution, food shortage

11. Homework Read p 383 – 387 P 389 Problems # 1-5
This math will be on the Test! You may use a calculator but not your cell phone.
So Bring a CALCULATOR