1. Population Growth
Too Many Elephants

2. Elephant Reproduction
An average pair of elephants has about six offspring between the ages of 30 and 90 years.
Therefore the number of elephants in a herd should ________ (x__) every ____ years.

3. Elephant Population Growth

4. Figure out the numbers:
Make a table of elephant populations for the first 540 years of a herd starting with 2 elephants.
Draw a graph with the data from the table.

5. How Much Space?
After 2560 years the elephant herd would number 2.19 x 1020
They would equal the volume of the earth.
If the herd where in space they would form another planet.
According to

6. Are Elephants Unusual
Elephants are the SLOWEST reproducing animals of them all!
Even slower than the sloth.
Most animals would take over the world MUCH faster.

7. Why do populations grow so fast?
Populations of organisms do not experience linear growth. They experience geometric, or exponential, growth; you MULTIPLY the population, you don’t add to it.
The growth of populations is unlike the growth of pay you get from a job. You might get a one dollar per hour increase in pay every six months.
A population is MULTIPLIED every certain amount of time. Like if you got your pay multiplied by 2 every year. It would build up slowly at first and then FAST later.

8. Pay Over Time (linear vs. exp.)

9. Pay Over Time

10. The graph of a growing population starts out slowly, then begins to resemble a J-shaped curve.
Population Growth of Houseflies
1 million
Population size
500,000
100
One year

11. Why is the curve J-shaped?
As time passes there are more organisms reproducing so the population grows faster and faster.

12. Too Many Elephants Back to the Elephants
Elephants will rule the world!
Elephants HAVE had 2560 years to reproduce. In fact much more. Why have they not taken over the world? Why do organisms not reproduce until there are trillions of each type?
Limiting Factors