Pretest Unit 3: Population Ecology
1. What is a population and how do ecologists study it
2. Explain the difference between a niche and habitat
3. Explain the predator/prey relationship and carrying capacity
on the graph.
4. Explain why animals fight
5. Explain how certain factors limit a population
6. Explain animal extinction and how it affects an area
7. What is succession and how does it occur?
Species, Populations,
Community, and sampling
• LT: Organisms occupy a specific area
Species and Community
• Fact 18 A species is a group of organisms that are physically similar and can mate with
each other and produce offspring that can also mate and reproduce.
• Fact 15 A community is all the different populations that live together in an area.
populations
• Fact 16 A population is all the members of one species in a particular area.
• the entire group of items or individuals being studied
• Populations change over time
• There are many factors that influence a population
• Natural
• Unnatural
• Fact 38 Population density (number in an area) has a great impact on ecosystems
• Population dynamics is the study of how the characteristics of the population
change in response to changes in the environmental conditions
Bellwork` 10/30
1.
What are three things we learned about yesterday?
• You must have a sentence about each one
Sampling
• Sample: a part of the population being studied
• Sampling populations gives an idea of
•
•
•
•
Size- how many
Density- how many in a specific area
Dispersion- how close or far away from each other
Location- where species are located
• A representative sample of the population is needed in order to make a valid inference, or an
accurate prediction based on data
• Survey: a method of gathering information about a specific group of items or individuals
Example 1: A 7th grade homeroom was
surveyed to determine how many texts
students at Olean Intermediate Middle
School send each day.
• What is the population?
– All students in the school
• What is the sample?
– Students in the seventh grade homeroom that was surveyed
• Biased or unbiased?
– Biased. One class of 7th graders does not accurately represent all students
in the school.
Example 2: To track migration patterns of a particular species of bird,
scientists randomly tag, release, and track 50 birds of that species.
• What is the population?
• The species of bird being studied
• What is the sample?
• The 50 birds that the scientists tagged
• Tagged birds are specially marked birds that are tracked. Scientists use the data on
these birds to
make generalizations about an entire bird species.
• Biased or unbiased?
• Unbiased. The birds tagged were randomly
selected.
Four factors of population change
• Natality - births within the population
• Mortality - deaths within the population
• Immigration =-arrival of individuals from outside the
population
• Emigration =-departure of individuals from the
population
• Growth rate formula • (Crude birth rate + immigration rate) - (Crude death rate +
emigration rate) - Growth rate
Population changes affect communities
• As population in one species declines, other species may appear
• Human development now displaces other species and threatens
biodiversity
Picture Mapping
• Today you will create a visual representation about the topics we discussed
• Only pictures
• No words
• Detailed enough for a random person to understand the topics
•Species, Population, Community, Sampling.
Habitat and
Niche Notes
LT: Organisms occupy a specific area
• Habitat - A habitat is the specific
environment that provides the things
grow and reproduce.
• Includes living and nonliving elements
• Scale-dependent: from square meters to
• each organism thrives in certain
use)
• Habitat selection - the process by
which organisms actively select
• Availability and quality of habitat are
being
• Niche A niche is the role an
organism plays in its habitat, or
• total way of life or role of a
• Habitat use, food selection, role
• Interactions with other
• Specialists - species with
narrow niches and very specific
• Extremely good at what they do,
• Generalists = species with
broad niches that can use a
resources
• Able to live in many different
Predator and Prey Interactions
Organisms interact in different ways
• Predator prey interactions
• A predator is the organism that does the killing in a predation interaction.
• Prey is an organism that is killed and eaten by another organism.
• Competition
• Competition is the struggle between organisms to survive as they attempt to use the same limited
resource.
• Cooperation
• Cooperation is the process of groups of organisms working or acting together for their
common/mutual benefit
Population Size
A concept map of what effects the size of a population.
population grows
Decrease in predators
plenty of food
food shortage
Predators
Food
increase in
predators
POPULATION SIZE
population falls
overcrowding
Disease
increased aggression / competition
for resources
Animals that eat other animals
Populations of animals are often limited by the amount of food.
animals that eat other animals are called
predators
animals that predators eat are called
prey
Predator and prey
aadaptations
Predators are adapted to catching and consuming their prey.
Prey have adaptations to detect and prevent being eaten by
predators.
Prey Adaptations – General
Prey have adaptations to detect and prevent being eaten by
predators.
venomous coral
snake
mimicry
speed &
keen
senses
camouflage
warning
colors &
patterns
scarlet
kingsnake
Predator Adaptations –
General
Predators have adaptations to catch and consume their prey.
birds of prey have
keen eyesight and
sharp beaks and
talons
camouflage
allows
predators to
blend in with
their
surroundings
treefrogs
have special
pads on their
feet so they
can cling to
venomous snakes have
poisonous venom to
subdue their prey
kingsnake
s are
immune to
the venom
of
venomous
snakes
Predator–prey graph
There are always more prey than predators.
The prey always increases before the predators do.
Predator–prey graph
This population data comes from fur trapping records.
How are the populations linked?
Predator–prey graph
How does the lynx population depend on the number of snowshoe
hares?
estimated population size
(thousands)
150
snowshoe
hare
Take a closer
look at this part
of the graph.
lynx
100
50
0
1800
1820
1840
1860
time (year)
1880
1900
Predator–prey graph
section
Why does the peak for the lynx population always come after the
peak for the number of snowshoe hares?
snowshoe
hare
estimated population size
(thousands)
150
lynx
100
For the populations
to survive, there will
always be more hares
than lynxes.
50
0
1850
1855
time (year)
1860
1865
Predator–prey cycle
Predator and prey population sizes follow a cycle.
What happens if the prey population increases?
normal prey population
prey population
increases
prey population
increases
predator population
decreases
as less food
predator population increases
as more food
prey population decreases
because of more predators
Predator–prey cycle
Predator and prey population sizes follow a cycle.
What happens if the prey population decreases?
normal prey population
prey population
decreases
prey population
decreases
predator population
decreases
as less food
predator population increases
as more food
prey population increases
because of less predators
PREDATION
• is when an individual of one species (predator) eats all or most of an individual of another
species (prey).
• An everyday occurrence in nature.
Bellwork 11/10
1. Explain what a population is
2. Explain predator prey relationships (be sure to talk about the graph)
Populations change over time:
Limiting Factors in an Ecosystem
Limiting Factors
Environmental factors (either biotic or abiotic)
that prevent a population from increasing
Availability of Food
• basic need of all organisms to obtain energy from
• If food is not available, organisms may not
Water
• The right quantity and quality of water is a basic
Shelter
• A basic need of all organisms to find a suitable
to hide from predators, to sleep, to raise young,
• Shelter may be biotic (like trees), abiotic (like
Space
• A basic need of all organisms to have a certain
• Must be large enough to meet organism’s basic
water, shelter, mates, etc.
Predation
• An organism preys on and consumes animals
Disease
• Viral, bacterial, and fungal infections and
organisms
Habitat Destruction
• Loss of habitat through climate change,
Populations change over time:
Carrying Capacity
Bellwork 11/12/14
1. Explain what a limiting factor is
2. Give 4 examples of limiting factors
3. Explain how limiting factors effect animal populations.
Carrying Capacity
Carrying capacity is the largest population that an
area can support
• Maintaining a balance
https://www.youtube.com/watch?v=QI2ixJeIxEU
Carrying Capacity
• Carrying capacity is determined by limiting factors (both
abiotic and biotic)
• Limiting factors can include: number of predators, amount of
rain, temperature, amount of food, and disease.
• These factors are based on
•
•
•
•
•
Location
Time
Short term ~ seasonal changes
Long-term ~global changes in factors such as climate
Technology
Bellwork 11/13/14
1. What is carrying capacity?
2. How does carrying capacity effect a population?
Populations change over time:
Ecologic Succession
Learning Target: I will be able to explain how
populations in an area take over an environment
• Succession is the gradual process by which
ecosystems change and develop over time
• The change in an ecosystem that happens when one
community replaces another as a result of
changing biotic and abiotic factors
• Ecological Succession: Primary
• The establishment of a community in an area of exposed rock that does not have topsoil is called
Primary Succession.
• It occurs very slowly at first
• Ecological Succession: Primary
• The first organisms to arrive are usually lichens or mosses, which are
called pioneer species.
• They secrete acids that can break down rock
• Their dead, decaying organic materials, along with bits of sediment from the rock
make up soil.
• Ecological Succession: Primary
• Small weedy plants and other organisms become established.
• As these organisms die, additional soil is created
• Ecological Succession: Primary
• Seeds brought in by animals, water and wind begin to grow in the soil.
• Eventually enough soil is present for shrubs and trees to grow.
• Ecological Succession: Primary
• The stable, mature community that eventually develops from bare rock
is called a
climax community.
• Ecological Succession: Secondary
• Disturbances (fire, flood, windstorms) can disrupt a community.
• After a disturbance,
new species of plants
and animals might
occupy the habitat.
• Ecological Succession: Secondary
• Pioneer species in secondary succession are usually plants that begin to grow in the disturbed
area.
• This is much faster
than primary
succession
• Ecological Succession: End point?
• Cannot be predicted
• Different rates of growth &
human involvement
make it impossible to
know if a true climax
community has been
reached.
• http://www.schooltube.com/video/51a9a5aaf99f43e1830b/Chernobyl-Showing%20Succession
• http://www.youtube.com/watch?v=4RsMyVavT2Q
Conservation Biology
Conservation biology is the study of how to protect biodiversity.
Endangered, Threatened, and Extinct Species
A threatened species is a species that could become endangered in the near future.
An endangered species are species that are in danger of becoming extinct in the near
future
http://oceantoday.noaa.gov/endspeciesday/welcome.html
Extinction is the disappearance of all members of a species from Earth
http://www.youtube.com/watch?v=34ru-NECVEA
Habitat Loss
• If a habitat is destroyed or disrupted, the native species might have to relocate or they
will die.
• Destruction of habitat - such as the clearing of tropical rainforests, has a direct impact
on global biodiversity.
• Disruption of habitat - the declining population of one species can affect an entire
ecosystem.