Download Chapter 5 Section 1 How Populations Grow

Chapter 5
Section 1
How Populations
Grow
•List the characteristics used to describe a population
•Identify factors that affect population size
•Differentiate between exponential and logistic growth
Introduction 5-1 Activity
December 2, 2013
Write these questions and your answers on a sheet of paper.
• How many people are in this classroom? (include me
because I am a person)
• What is the room’s area? (there are 39.37 inches per
meter)(area is length x width)
• How many people are there in the room per square
meter? (divide the number of people by the room’s area)
Population density = # of individuals/unit area
• 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?
List the characteristics used to
describe a population.
• Three important characteristics of a
population are its geographic distribution,
density, growth rate, and population age
structure.
– Density – the number of individuals per unit area.
This can vary greatly depending on the species
and its ecosystem.
– Geographic distribution – also called the range,
the area inhabited by a population. This can vary
greatly.
List the characteristics used to
describe a population - continued
– Growth rate – the rate at which the size of a
population changes
– Population age structure – the age distribution of
the individuals in that population
Population growth – Three factors can affect
population size:
- The number of births (if you have more births
than deaths the population size grows)
- The number of deaths (if you have more deaths
than births the population size shrinks)
- The number of individuals that enter or leave a
population
- Immigration is the movement of individuals into an
area
- Emigration is the movement of individuals out of an
area
Differentiate between exponential and
logistic growth.
Logistic Growth
• This occurs when a
population slows or stops
following a period of
exponential growth
• As resources become less
available, the growth of a
population slows or stops.
• This ususally appears as a
“S-shaped” curve on a line
graph.
Exponential Growth
• This occurs when a
population grows at a
constant rate
• Under ideal conditions with
unlimited resources, a
population will grow
exponentially.
• This usually appears as a “Jshaped” curve on a line
graph.
Post Notes Assignment
• Write questions numbered 1-6 on page 123 and
answer them.
• Then write the definitions for the vocabulary
terms found only in section 1
1.
2.
3.
4.
5.
6.
population density
immigration
emigration
exponential growth
logistic growth
carrying capacity