Exploration Phase
Topic: Biotic Potential of Natural Populations
Activity 1
Of course, exponential growth rate for natural populations is not realistic in most cases because
death rate is not included. The following activity examines population growth with a 25% death
rate in each generation. The first three lines of the table have been completed. Fill in the rest
using Excel or the table below (NOTE Round any fractions down to whole numbers). Continue
for 12 generations. Graph x=Generation, y= Number at Start of Generation
Generation
1
2
3
4
5
6
7
8
9
10
11
12
Number at start of
generation
2
3
5
16
Number after
Reproduction
4
6
10
Loss due to 25%
death
1
1
2
Number
Remaining after
death
3
5
8
Concept Introduction
Explain how death rate changes the shape of the course as compared to exponential growth.
The curve you generated is an example of biotic potential. Formulate a draft definition of biotic
potential.
Application
HUMAN BIOTIC POTENTIAL?
Year
Millions of Humans
Activity 1
-10000
1
Of course humans die. Are humans undergoing biotic
-5000
5
growth? Enter the data into an Excel spreadsheet and graph
-4000
7
it, or use the graph paper at the end. [The data was cut and
-3000
14
pasted from two different locations on the US census
-2000
27
website.* http://www.census.gov Historical Estimates of
-1000
50
World Population]
1
170
500
190
Human Biotic Potential Line Graph
y=population (millions)
x=years
1000
254
1500
425
1600
545
1700
600
1800
813
1900
1,550
1950
2,400
1960
3,039
1970
3,708
1980
4,454
1990
5,284
2000
6,085
2010
6,812
2020
7,510
2030
8,111
2040
8,623
2050
9,050
Projections based on current trends.
Describe the human population growth graph. Use the term
"Biotic Potential" in the description.
Activity 2
"Unlike plagues of the dark ages or contemporary diseases we do not understand, the modern
plague of overpopulation is soluble by means we have discovered and with resources we possess.
What is lacking is not sufficient knowledge of the solution but universal consciousness of the
gravity of the problem and education of the billions who are its victims."
MARTIN LUTHER KING, JR.
1929-1968
Will the earth hold 1015 people? Physically it might be able to hold 30% of 1015.
Hold on—we will explore carrying capacity during the next lesson. We need to finish
with biotic potential.
According to the Population Institute (2006 Annual Report), global human population
growth is about 1.3% annually, with virtually all the growth occurring in developing countries.
In The Population Challenge: Key to Global Survival (2007), the mean average growth
among the 20 most populous developing countries was reported to be 2.4% annually, with
Afghanistan leading the group at almost 4%.
Just for argument sake, assume the earth can physically hold 1015 people. Of course, the
number of people the earth can actually support is much less. The current global population is
about 6,500,000,000. How long will it take to reach about 1015 at the following global growth
rates?
a) 1%
b) 2%
c) 3%
d) 4%
You need to open an Excel spreadsheet for this activity. Try to solve the problem and answer the
question before asking for assistant. Please do not run from the building screaming.
Optional Activity
A global average of 1.13 metric tons of CO2 carbon per person per year is released into the
atmosphere.
1.13 metric tons of CO2 per year x 6,500,000,000 people = current annual production of carbon
dioxide.
Suppose we cut the global average to 0.5 metric tons of CO2 carbon per person per year.
How long would it take to reach the current annual production based on current population
growth rates?