1. Populations

2. Size  Difficult to measure as many organisms are mobile.  Sample size  Scientists count how many individuals in a small area and multiplied that by the total area.  Only an estimate. Why?

3. Density  How crowded a population with in a particular location is.  Expressed as a # of individuals per unit of area or volume  Ex: 100 people per square kilometer.

4. THINK ABOUT IT!!!  Which one would be more densely populated? a) 50 people per square meter b) 500 people per square kilometer

5. Dispersion  Spatial Distribution of individuals in a population  Clumped-organisms clustered together Resource availability & social behavior (herding)  Uniform-fairly evenly distributed Some organisms avoid others in the populations  Random-location of each individual is independent of the others in the population rare

7. Growth Rates  Dependent upon birth rate, death rate, immigration & emigration  Per capita = per 1,000 individuals in the population  Ex: birth rate = 52 births = 52/1,000 =.052 births per capita per year death rate = 14 deaths = 14/1,000 =.014 deaths per capita per year

8. Equation Birth rate – death rate = growth rate

9. THINK ABOUT IT!!!  What is the per capita growth rate if the birth rate is 52 and the death rate is 14?  In a population of 50,000, how many INDIVIDUALS will the population increase by?

10. Exponential Growth  In a positive per capita growth rate, each generation produces a larger amount of individuals than the previous generation.  The RATE at which the population grows, increase over time.  J-curve

11. Limiting Factors  Biotic and abiotic factors that limit population growth.  Abiotic factors include water, space, shelter, weather  Biotic factors include predation, competition, disease

12. Logistic Growth  Population will grow exponentially until limiting factors regulate it.  S-curve  Carrying capacity-the number of individuals the environment can support over a long period of time.  When carrying capacity is reached, birth rate = death rate and no growth is occuring.  Fluctuates with changes in the environment (greater when prey/food is abundant and smaller when prey/food is scarce.