Population Biology

1
Population Biology

• Class Notes 6

2
I. Graphs of population growth

• Populations do not show linear growth, but
  exponential growth.
• 1. Exponential growth means that as a population
  gets larger, it grows faster.
• 2. This graph looks like a letter j.

3

• B. The population cannot grow forever because of
  limiting factors
• Ex food, water, space
• C. Eventually the ecosystem will reach its
  carrying capacity
• NO MORE ROOM!

4

• When the population falls below carrying
  capacity, the population will increase again,
  when it goes above the capacity, the population
  will decrease.
• This graph looks
• like an S

5
II. Patterns of population growth

• Some organisms show patterns of slow growth,
  others show patterns of fast growth
• A. Rapid growth patterns are shown by organisms
  like insects who live in an unstable environment.
  They must reproduce before they die!

6

• B. Slow growth patterns are shown by bigger
  organisms that live in a more stable environment,
  such as elephants or bears.
• They live in a climax community. There
  is plenty of time to reproduce.

7
Summary

• How is exponential growth different from linear
  growth? Why do populations that are growing
  exponentially stop? What factors are fast or slow
  growth patterns based upon?