1. Do Now 4.5 (Advisory Schedule)
OBJECTIVES:
Describe the characteristics of populations using the terms size, density, dispersion, and age structure.
Describe and compare linear growth and exponential growth.
TASK: Answer, don’t copy:
There are approximately 640,000 people that reside in Baltimore City
The land area of Baltimore is about 200 km2 (about 80 mi2)
What is the human population density of Baltimore?
In people / km2
In people / mi2

2. Measuring Populations
Population size: how many organisms are in the population
Population density: how many organisms there are per unit area (i.e. square km)
Population dispersion: how individual organisms are arranged in the population
Age structure: the relative distribution of organisms by age in the population

3. Population Size How many organisms are there?
Simple count
Sampling and average.
A microbiologist samples a population of bacteria by counting the number of cells in 1 mL of the liquid they’re in, with the following results
Sample 1: 27 individuals
Sample 2: 33 individuals
Sample 3: 30 individuals
What is the population size if there are 100 mL of solution all together?

4. Population Density = Number/Area
There are approximately 640,000 people that reside in Baltimore City
The land area of Baltimore is about 200 km2 (about 80 mi2)
What is the human population density of Baltimore?

5. Population Dispersion: How a population is distributed

6. Human Population Dispersion

8. Population Growth Rates
Growth Rate: The
amount by which the
size of a population
changes in a given time
Birth
Immigration
Emigration
Death / Mortality

9. Growth Curves
Logistical / Linear
Exponential
Logistical / Linear

10. Exponential Growth

11. Human Population Growth
In the 27 years since this graph the human population has
Grown by over 2,000,000,000 people.

12. Populations will grow until there is something that limits them
Food, water, or other resources
Predators, parasites, disease, etc.
Carrying Capacity: The maximum population that is sustainable for long periods of time in an ecosystem.
Resource Limits
One limiting resource constrains growth:
Leibig’s Law of the Minimum

13. Typical Growth Curve

14. Do Now 4.6 OBJECTIVES: TASK:
Describe and differentiate the three basic survivorship curves of different reproductive strategies
TASK:
Complete the first part of the populations practice problems from yesterday (drawing 2 populations)

15. Ooops… decimals… Houston, we have a problem
The assignment P259 (participation weeks 25-29) was incorrectly entered with a 40x multiplier (instead of 4.0x)
As a result, the grade some of you will receive for the 3rd quarter may be slightly inaccurate (+/- 0-3 points)
Adjustments will be made to 4th quarter grades
The list…

16. Survivorship Curves 3 Strategies for success:
Type I: low # of offspring, high survival rate of young. (aka k-selection)
Type III: high # of offspring, low survival rate of young. (aka r-selection)
Type II: moderate # of offspring and survival rate of young.
Survivorship Curves

17. Number of offspring per reproductive cycle
Octopus v. Giant Panda
Number of offspring per reproductive cycle
~200,000
1-2
Frequency of cycle
1 / lifetime
2 years, 6-8 times / lifetime
Gestation
~ 6 months (external eggs)
~ 4 months
Parenting
1.5 – 2.0 years

18. Find size, density, dispersion, and age structure of this population.
Total area = 3 km2 Blue = young, white = old, turquoise = middle aged
Find size, density, dispersion, and age structure of this population.

19. Population Growth Classwork / Homework
Practice worksheet
Reading on Syllabus