Characteristics of populations
 Geographic
distribution- area inhabited
by a population.
 Density-
# of individuals per unit area
 Growth
rate
 Age
Structure - shows the distribution of
various age groups in a population.
Challenge

Suppose there are 150 bullfrogs living in a pond that
covers an area of 3 square kilometers. What is the
density of the bullfrog population?

Population Density = Number of individuals
Unit Area
= 150
3 square kilometers
= 50 bullfrogs per square kilometer
 On
a blank sheet of paper, make up your
own challenge problem similar to this one.
Write your name on it.
Population Growth
 Can
be positive (increasing) or negative
(decreasing)
3
factors affect population size
1. Number of births
2. Number of deaths
3. Number of individuals entering or
leaving
Immigration
 Number
of people entering the
population
Emigration
 Number
of people leaving a population.
2 Types of Population Growth
Exponential
Logistic
Exponential Growth
 When
individuals in a population
reproduce at a constant rate.
 Under
ideal conditions and with unlimited
resources, a population will grow
exponentially.
Exponential Growth
Logistic Growth
 Occurs
when a populations growth slows
or stops after a period of exponential
growth.
 As
resources become less available, the
growth of a population slows or stops.
Carrying Capacity
Largest
number of
individuals of a population
that a given environment
can support.