Population Student NOTES

Population Ecology
UEQ: Why populations change?
Name: _________________________________Date: ___________________Period: ____
1. How do ecologists organize and study life?
2. What are the important characteristics of populations?
3. What factors determine whether, and how, a population’s size changes?
Ecologists study _______ at many levels, from individual organism to the entire _____________.
Ecology: “eco” means ____________, “ology”means _____________________.
Cells – Tissue-Organs – Organ systems -Organisms
Population – a group of individuals of the same ____________ that live in the ________ area
at a given time.
Example: a group of white-tailed deer in an oak-hickory forest in southeastern PA
Community - __________ of living organisms that interact with one another in a particular ____.
Example: deer, mice, bushes and snakes in the forest community
Ecosystem: a community together with its ____________ environment
Biosphere: all parts of the __________ that hosts life, with all of its ___________ and
Ecosystems include both biotic and abiotic factors. Biotic factors are parts of the ___________
that are ____________. Abiotic factors are parts of the ecosystem that are
Biotic examples: __________________________________________________________
Abiotic examples: ________________________________________________________
Organisms depend on _________ provided by their __________ for survival. The specific
environment in which an organism lives is its ___________. A habitat provides an organism with
resources. A ____________ is anything an organism needs to ____________.
The ____________ health of a population can often be ______________ by tracking how its
size changes.
Population _____ describes the number of individual ___________ present in a given population at
a given ___________.
Deals with the # of individuals of a particular ________ that are found in an area and how and
why those _________________ change or remain fixed over time.
Population ecologists study…
How populations respond to its _______________
Competition for resources, predations, _________ and other environmental pressures
•Determine population size by _______________.
Instead of counting every individual, ecologists
count every _________________ in a small area then _____________ the number of
individuals in the larger ___________.
Population density describes the _____________of individuals within a population per unit area.
For example: 1500 golden toads per 4 sq. kilometers
In general, _________animals have lower population _______ because they need more
_______. High population __________ can make it easier to find __________ and group
together. However, it also leads to more competition for __________. Overcrowded organisms
can also lead to _______________of disease and vulnerable to predators.
Age structure diagrams show the number of _______& _______in different age groups within a
population. ____ ___ ____________ describes the relative number of organisms of each age
with in a population. Age structure diagrams are a visual _______to show the age structure of
1. Stable – approximately the _______ number of individuals at each age grouping, mix of young
and old
2. Growing – mostly ___________
3. Declining – the largest portion of population is ___________
Generalized age structure diagrams
A population’s growth rate is determined by _____________, deaths, _________________ &
All things being ________, when a population __________ is greater than its death rate,
population size will __________. When death rate is ___________ than its birth rate, population
sizes will ______________.
1. Birthrate – number of _________births per 1000 in a given year
2. Death rate – number of ________ per 1000 in a given year
In addition to births & deaths, population size can also change by ______________ moving in & out.
3. Immigration – movement of individuals into a ___________________
4. Emigration – movement of individuals ____________ of a population
Growth rate (r) = birth rate (b)+ I – death rate (d) + E
Population growth is typically reported as a net change per 1000 individuals.
Exponential growth is when a population ___________________by a fixed percentage each year.
Exponential growth occurs in nature only when the starting population is __________& the
environmental conditions are ____________. This type of growth usually does not last _______.
Most populations are constrained by __________ ____________.
Limiting factors are characteristics of the environment that limit ______________ _________.
Limiting factors determine a population’s carrying capacity.
Example: New population is introduced…mold growing on bread.
Logistic Growth describes how a population’s initial exponential_________ is slowed & finally
stopped by limiting factors.
•Carrying capacities are not __________.
Carrying capacity is the largest population ________a
given environments can sustainably _____.
•Examples of limiting factors:
Limiting factors have more of an effect in ___________populations & other limiting factors affect
all populations in the ______________ way.
1. Density–DEPENDENT factor: factors that ____________ the population size or density
A. Disease (example: HIV)
B. __________________
C. Predators
D. Parasites
E. ______________
2. Density INDEPENDENT factor: affect ALL populations, regardless of size
A. Temperature
B. ________________
C. Floods
D. Drought
E. ____________________________
Biotic potential is the maximum ability to produce ____________________ in ideal conditions.
Biotic potential is based on…
• ____________ at which reproduction takes place
% of __________________ that an organism can reproduce
Number of ______________ in each reproduction period
Generally larger animals have a ___________ biotic potential than microscope organisms.
A. Rapid life history (example: mosquitoes)
a. Rapid reproduction
b. High number of offspring
c. Small __________ size
d. Organisms mature ____________
e. Reproduce ____________
f. Organisms have a short life ______
B. Slow life history (example: elephant)
a. Slow reproduction
b. _________ number of offspring
c. Large body size
d. Organisms mature ____________
e. Reproduce late
f. Organisms have a long __________span
g. Organisms tend to have _____________care
1. Fill in the 8 ovals with different limiting factors.
2. Then, go back and color the limiting factor.
a. Density dependent - red
b. Density independent – blue
Population size
Turkey Vultures
The graph at the right shows the
average number of turkey vultures
that were counted on protected
lands at the Hawk Mountain
Sanctuary in Pennsylvania. In
this activity, you will interpret the
graph by describing the trends that
it shows and drawing conclusions
about the annual migration cycle of
turkey vultures.
Interpreting the Graph
To understand the information in a graph, the first step is to figure out the information that
it shows. Study the axes and note the trend shown by the graph.
1. What do the x and y-axes show?
2. What do the two bars for each month represent?
3. To describe the annual trend in the graph, look at the overall changes in the bar height
over the entire year. Describe what you see.
Inferring From the Graph
Turkey vultures migrate from the north onto the sanctuary lands and reside there for a while
before migrating south. You know that when the vultures migrate through the sanctuary, they
will increase the population size. Answer the questions below to help you identify when the
vultures migrated through the sanctuary.
4. In which two months is the turkey vulture population significantly greater than in the
other months?
5. When would you conclude that the vultures migrating from the north arrive at the
6. When would you conclude that the vultures leave the sanctuary and begin to migrate
The Disappearance of the Golden Toad
What can cause a thriving population of
animals to disappear in the span of one or
two years? In the case of the golden toad
of Monteverde in Costa Rica, thousands
of toads were initially observed during the
mating season each year. Then one year,
there were only a few toads. Two years later,
only a single toad was observed, and then
the toads disappeared completely.
Use the information in The Disappearance of the Golden Toad to answer the questions below.
1. How many golden toads could be observed during mating season when the toad’s
population was thriving?
2. Based on the golden toad population’s habitat, why was extinction of the golden toad
3. Explain why it was significant that large numbers of other frogs and toads became extinct
at the same time the golden toads disappeared.
4. Explain what happens to cloud mist as the number of “dry days” increases.
5. Assuming the Lifting Cloud Base Hypothesis to be correct, which part of the Monteverde
cloud forest would likely be the least affected by the decrease in moisture? Explain.
Relate this case to the Big Question: “How do changes in population size
relate to environmental conditions?” Describe the sequence of events that could have led
to the extinction of the golden toad, according to the Lifting Cloud Base Hypothesis.
Interpreting Ecological Data
(25 points)
Graph 1: Rabbits Over Time
1. The graph shows _____________________________ growth curve.
2. How many rabbits were in the environment on May 1st? ______________________
3. The carrying capacity for rabbits is ___________________.
4. During which month were the rabbits in exponential growth? _________________
Graph 2: Average Toe Length
In 1800, about how many people surveyed had a 3 cm. toe? ___________________
2. How many in 2000? ________________________
3. By looking at the median, what is the average toe length in 1800? _______________
4. By looking at the median, in 2000, what is the average toe length? _______________
5. What has happened to the average toe length over the past 200 years?
Graph 3: Mexico and US
In Mexico, what percentage of the population is between 0-4 years of age? _________
2. In the US, what percentage of the population is between 0-4 years of age? _________
3. How would you describe the growth of the population for the US? ____________
4. How would you describe the growth of the population for Mexico? ____________
5. Which population is growing the fastest? How do you know this??
6. Which age group has the smallest number in both countries:
a. US: _________________
b. Mexico: ______________
Graph 4: Snakes & Mice
The data table shows populations of snake and mice found in an experimental field.
1. During which year was the mouse population growing the fastest? ________________
2. During which year was the mouse population at zero population growth (closest to zero
growth)? ____________
3. What is carrying capacity? _____________________________________________
4. What is the carrying capacity for snakes? _______________________
5. What is the carrying capacity for mice? ________________________
6. What is the calculation for growth rate? _______________________________
7. What is the rate of growth (r) for mice during 1970? ________________
8. What is the rate of growth (r) for mice during 1980? ________________
Population Review worksheet
Matching: Please match the vocabulary word with the correct definition.
____1. The number of deaths per 1000 individuals
A. population density
___2. Characteristic in the environment that restricts
Population growth.
B. biotic potential
___3. The # of individuals in a population per unit of area
C. limiting factor
___4. The growth rate of a population under ideal conditions
D. birth rate
___5. The number of births per 1000 individuals
E. death rate
__6. Factor that affects population more as the population
F. growth rate
___7. Weather related factor that affects ALL populations
Regardless of density
G. immigration
___8. Migration of individuals into a population from
factor another area or country
H. density independent
___9. Change in size of a population over a period of time
I. density dependent
___10. The migration of individual from a population
J. emigration
Short Answer: Answer each question carefully.
1. Give 2 examples of density independent factors.
2. Give 2 examples of density dependent factors.
3. What are some factors that can slow the growth of a population?
4. What happens in an ecosystem when there are too many of one species?
5. How can population sizes be monitored?
6. The graph below shows the growth of two populations of paramecia grown in the same
culture dish for 14 days. Which ecological concept is BEST represented by the graph?
7. Sequence of order: Place the following biological levels in order from smallest to largest.
_____organ system
_____ atom
WORD LIST – Use the words below to complete #8-12.
Age structure
population sampling
8. An example of an abiotic factor is __________________________________.
9. _________________________ describes the relative number of organisms of each age with
in a population.
10. All the dogs that live in Enola make up a(n) ______________________.
11. The plants and animals interacting in the same ecosystem would represent a
12. A pond and all the organisms it contains make up a(n) ______________________________
Populations (8 days)
Ecology – Mrs. Sim
PA Standards
4.1.10.A – Explain the biotic & abiotic components of an ecosystem and their interactions.
4.1.12.A – Analyze the interdependence of an ecosystem.
Unit Essential Question(s):
Instructional Tools:
Why populations change?
Studying ecology
Lesson Essential Questions:
How do ecologists
organize and study
M&M population lab
Age structure
How many fish in Bud
Describing populations
Lesson Essential Questions:
Population growth
Lesson Essential Questions:
What are the important
characteristics of
What factors determine
whether, and how, a
population size changes.
Population ecology
Population sampling
Population size
Population density
Age structure
Age structure diagram
Exponential growth
Limiting factor
Carrying capacity
Logistic growth
Density dependent factor
Density independent factor
Biotic potential
Growth rate
1) Ecology: the study of how organisms interact with one another and with their environments.
2) Population: the members of a species that live in the same area
3) Community: all the population in a particular area
4) Ecosystem: all the living things and their physical environments within a particular area
5) Biosphere: the earth and all of its organisms and environments
6) Abiotic: non-living factors in the environment
7) Biotic: living factors in the environment
8) Habitat: the specific environment in which an organisms lives
9) Resources: anything an organisms needs; includes nutrition, shelter, mates and breeding sites
10) Density dependent factor: a limiting factor whose influence changes with population
density; includes competition, predation, and disease
Density independent factor: a limiting factor whose influence is not affected by
population density; includes catastrophic events
Limiting factor: a characteristic of the environment that restricts population growth
Carrying capacity: the largest population a given environment can support
14) Exponential growth: the pattern of population growth in which a population increases by a
fixed percentage each year
15) Logistic growth: the pattern of population growth in which exponential growth is slowed &
finally stopped by limiting factors
Population sampling: estimating the number of organisms in a large area
Population density: the number of individuals in a population per unit of area
Population size: the number of individual organism present in a population at a given time
Biotic potential: the growth rate of a population under ideal conditions
Emigration: the movement of individuals away from a given area
Immigration: the movement of individuals to a given area
Age structure: the relative number of organisms of each age within a population
23) Age structure diagram: a chart that shows the age distribution of a population; also called
age pyramid
Growth rate: the change in a size of a population over a specific period