Chapter 5
POPULATIONS
• 5.1 How Populations Grow
•Pages 130-136
• 5.2 Limits to Growth
•Pages 137-141
• 5.3 Human Population Growth
Pages 142-145
Red Crabs on Christmas Island in the Indian Ocean-
What assumptions can you make
about this population?
http://animal.discovery.com/videos/fooled-by-nature-christmas-island-crab-migration.html
Chapter Vocabulary
5.1 Pages130-136
• Population density
• Age structure
• Immigration
• Emigration
• Exponential growth
• Logistic growth
• Carrying capacity
5.2 Pages 137-141
•Limiting factor
•Density-dependent limiting
factor
•Density-independent
limiting factor
5.3 Pages: 142-145
•Demography
•Demographic transition
5.1
How Populations Grow
What is a Population?
• A population is:
• _____________________________________
______________________________________
How do Ecologists Study Populations???
1.) Geographic Range
2.) Density and Distribution
3.) Growth Rate
4.) Age Structure
1. Geographic Range
• _______________________:
– The area inhabitated by a population
– Can vary in size
• Small - Bacteria in a rotting pumpkin (<1 cubic meter)
• Large - Cod in the Atlantic (hundreds of miles)
2. Density and Distribution
• ______________________:
– The number of individuals per unit area
– Vary in densities
• ______________________:
– How individuals in a population are spaced out
across the range of the population
• 1.) _______________
• 2.) _______________
• 3.) ______________ (most concentrated)
3 Types of Population Distribution
3. Growth Rate
• _______________determines whether the size of
a population increases, decreases, or stays the
same.
• Examples:
– __________________:
• When the population size stays the same
– __________________:
• Population increases
– __________________:
• Population decreases
4. Age Structure
• ______________________:
– The number of males and females of
each age a population contains
– WHY?
• ___________________________________
___________________________________
• ______________________________
What factors affect population growth?
1.) ______________
2.) ______________
3.) ______________
4.) ______________
Reasons for 3 & 4:
– Food shortage
– Overcrowding
– Looking for mates
Why does a population grow?
• ________________
• ________________
• ________________________
• ________________________
• ________________________
Exponential Growth
• ___________________:
– The size of each
generation of offspring
will be ________ than the
generation before it
– The larger the
population gets, the
___________ it grows
– Under _________
conditions, a population
will grow exponentially
Rates of Growth
• Reproduce Rapidly:
– Bacteria
• 1 day = 4,720,000,000,000,000,000 individual cells
• Reproduce Slowly:
– Elephants
• 1 offspring every 2-4 years
Logistic Growth
• ____________________:
– Occurs when a population’s growth
_________________________, following a period
of exponential growth
– 3 Phases:
• Phase 1 – Exponential Growth
• Phase 2 – Growth slows down
• Phase 3 – Growth stops
– When birthrate and death rate are the same
– When emigration equals immigration
Carrying Capacity
• _______________
The maximum
number of
individuals of a
particular species
that a particular
environment can
support
5.2
Limits to Growth
Limiting Factors
• ________________________:
– A factor that controls the growth of a population
– Determine the ______________________of an
environment for a species
– Examples:
•
•
•
•
•
•
________________
________________
________________
________________
________________
________________
How might each of these factors increase the death rate in a
population?
5.3
Human Population Growth
Has human population size changed over time?
• Tends to ______________________
• Reasons:
– Medication
– Sanitation
Patterns of Human
Population Growth
• ____________________________:
– The scientific study of human populations
– Predicted by:
• Birthrates
• Deathrates
• Age structure