Study Guide: Populations in Ecosystems
In an ecosystem, the populations of primary and secondary consumers rise or fall in similar patterns. This
occurs because changes in one population directly affect those of the other population.
The following graph shows the deer and wolf populations in one state from the year 1966 to 1985. Study the
graph and then answer the questions below.
1.
What happened to the deer population from 1966 to 1968? ___________________________
What is this phase called? _____________________________________________________
2.
What happened to the deer population from 1968 to 1970? ___________________________
What is this kind of growth called? ______________________________________________
3.
What happened to the deer population from 1970 to 1973? ___________________________
4.
What happened to the deer population from 1973 to 1975? __________________________
5.
Name three density-independent factors that might have caused this dramatic change?
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________
Density dependent factors? ____________________________________________________
6.
What happened to the wolf population from 1973 to 1975? ___________________________
7.
How long did it take for the change in the deer population to markedly affect the wolf population?
________________________________________________________________
8.
In which two years were the wolf and deer populations the same size? __________________
Study Guide: Populations in Ecosystems
Scientists have developed a language for explaining population growth and its relationship to ecosystems.
These terms used by ecologists help people clarify the complex phenomenon of increasing populations.
Exponential Phase
Limiting Factor
Birth Rate
Growth Rate
Carrying Capacity
J-Curve
Death Rate
Stabilizing Phase
Lag Phase
With the human population growing slowly, the period during which our ancestors were hunter-gatherers,
was a (1) ____________________. The scarcity of food was a (2) _______________, responsible in part
for this slow growth. From the year 1840 to the present, however, humans have been in an (3)
______________________ of growth, in which the population has repeatedly doubled. A graph of human
population growth is the kind of curve called a (4) _______________. Environmental factors have not yet
restricted human growth. This means that earth has not reached its (5) _____________________ with
regard to humans. Since the (6) ______________ still exceeds (7) _____________________, the
population of humans is still increasing, and has not yet reached the (8) _____________________ of
growth.