Download Dynamic ecosystems

DYNAMIC
ECOSYSTEMS
Ecology
• Ecology
• The study of the interactions of organisms with
each other and their environment.
Ecology
• Environment
• The surroundings or conditions in which a
person, animal, or plant lives.
Ecology
• Who studies ecology?
• Ecologists are scientists who study small
areas of Earth called ecosystems
• Ecosystems
• Biological community of interacting organisms
and their physical environment
Levels of Organization
• Species
• Group of organisms whose members have
similar characteristics and can interbreed with
one another, but not with members of other
such groups
• Individual
• One single living organism
Levels of Organization
• Population
• A group or organisms of the same species
• Each population has
a place where it lives
called its habitat
Levels of Organization
• Community
• The group of interacting populations of different
species that occur together in an ecosystem
Levels of Organization
• Ecosystem
• All the living and non-living things that interact
with one another in a given area
Ecosystems
• An ecosystem is made up of 2 groups of
things:
• Biotic (living)
• Living organisms
• Plants, animals, fungi, bacteria
• Abiotic (non-living)
• Physical environment
• Water, sunlight, oxygen, soil, nutrients,
temperature, wind
Levels of Organization
• Biome
• A collection of regions of Earth that have a certain
climate and certain types of living things; usually plants.
Levels of Organization
• Biosphere
• Consists of all living organisms on Earth plus
the environments in which they live
More Definitions!
• Niche
• An organism’s particular role in an ecosystem,
or how it makes its living (what it eats, when it
eats, etc.)
• ex. The flightless dung beetle occupies a niche
exploiting animal droppings as a food source
ENERGY FLOW
• All living things need energy to live
• What is the source of that energy?
The Sun!
Photosynthesis
• Producers (plants) use the sun’s
energy to make food
• This process is called photosynthesis
• Energy from light is absorbed by
proteins in leaves that contain
green chlorophyll pigments
• Convert light energy into sugars
• Animals must eat other organisms to
get energy
• Breaking down glucose to release
energy is called cellular respiration
• An organism has to transform the
chemical energy into a form that can
be used
• Organisms that make their own food are
called Autotrophs
• “Auto”=self “Troph”=feed
Plants

Moss

Some
Bacteria

Algae

• Organisms that use cellular respiration to
get energy are called Heterotrophs.
• “Hetero”=other “Troph”=feed
Some Bacteria
Animals
Fungi
• Herbivores eat only plants
• Carnivores- eat mainly meat
• ex.
• Omnivores- eat both plants and
meat
• ex.
• Decomposers consume and break
down dead organisms or waste matter
into simple substances
• Send nutrients back into the soil
• ex.
https://www.youtube.com/watch?v=bW7PlTaawfQ
• Food chains show the relationship of
feeding and energy transfer in
organisms of an ecosystem
Food Chains
• Producers get their energy from the sun
• Primary consumers (herbivores) feed directly on
producers
• Secondary consumers feed on primary
consumers
• Tertiary consumers feed on secondary
consumers
• Many food chains become connected
in a complex relationships called a
food web
• Each step in a food chain is known as a
trophic level
Energy moves
up the trophic
levels
• Scavengers are carnivores that feed on dead
animals
• ex. vultures, hyenas, seagulls, ravens
• Pyramid of biomass shows the total amount
(mass) of living material at each trophic
level
• Only 10% of the energy received from food is
stored in the body; 90% is used to run your
organs
0
100
• Pyramid of energy shows the total amount of
energy at each trophic level
• Plants capture light energy and use that energy to
make glucose (sugars)
• Sunlight provides the energy needed by
chlorophyll to change molecules of carbon
dioxide and water into glucose
• Oxygen is also released in this reaction
Why is it important to us?
• We cannot make our own food (glucose,
energy), we must get our food from plants.
• Plants are the first step in the food chain.
• The oxygen released during photosynthesis
is necessary for all living things.
Cellular Respiration
• The release of chemical energy for use by cells.
• The breakdown of glucose molecules to release
energy
• Once the energy that was in sunlight is changed into
chemical energy by photosynthesis, an organism has
to transform the chemical energy into a form that can
be used by the organism.
Energy Pyramid
• Species in the highest trophic levels have less
energy available to them than species near the
bottom
• This often results on their populations being
much smaller than species lower in the food
chain (number of predators<herbivores)
0
100
• Each step in a food chain is known as a
trophic level
Energy moves
up the trophic
levels
Population Control
• IF conditions are ideal (excess food, water, shelter,
few predators) populations will grow rapidly!
“Exponential”
growth cannot
continue forever!
Ideal Population Growth
• Conditions are never ideal
• A population cannot grow forever
The
environment
sets limits on
population
growth
Real Population Growth
• Carrying capacity: maximum population of
a species supported by the environment
• Ex. How many people can fit on a lifeboat
• What factors might affect carrying capacity?
• Food availability,
• Water,
• Environmental conditions
• Space
• Births
• Deaths
• Closed populations
• Only births or deaths change the population
• eg. An island
Population Growth= (births) – (deaths)
• Open populations
• Births/deaths and moving in/out change the
population
• eg. Manitoba
• Immigration: moving into a population
• Emigration: moving out of a population
Population Growth= (births+immigration) –
(deaths+emigration)
Factors that limit population growth
• Many environmental factors limit population
growth
• Density-dependent factors affect large and
crowded populations
• Disease- disease spreads faster in dense areas
• Predation- more opportunity for predators
• Competition- forced to compete for resources
• Stress- overcrowding leads to early deaths
• Density-independent factors affect a population
regardless of its size/density
• Natural factors- without human intervention
• eg. Bad weather, natural disasters (floods, fire, drought)
• Human activity- because of human intervention
• eg. Pollution, deforestation
• Populations are restricted by natural ecosystems
• If too dense, density-dependent factors act to limit
the populations of that species
• Density-independent factors limit population
regardless of size
• Populations usually regulated around the carrying
capacity
• Why do we care if the number of organisms
in an area is growing or shrinking?
• Populations that are growing or shrinking
can tell us if there are potential problems
happening in the environment
Exponential Growth Curve
• IF conditions are ideal (excess food, water, shelter,
few predators) populations will grow rapidly!
“Exponential”
growth cannot
continue forever!
Ideal Population Growth
• Conditions are never ideal
• A population cannot grow forever
The
environment
sets limits on
population
growth
Real Population Growth
Logistic Growth Curve
• Also known as an “S” Curve
• Resources (food, water, space) become more scarce
• Rate of population increase begins to slow
Carrying Capacity
• The largest population of a species that a particular
environment can support
• Affected by factors such as resource availability and
weather
• The population of a species will grow rapidly at first.
• Once the population has reached the level that the
ecosystem can support, the population varies UP and
DOWN around the CARRYING CAPACITY.
• Point A = lag phase
• There are very few
organisms in the
beginning so the
reproduction rate is
low. The population
grows very slowly.
• Point B = acceleration
phase
• As the young grow
up and begin to
reproduce, the
population enters the
acceleration phase
• Point C = exponential
phase
• The population
begins to grow very
quickly in the
exponential phase
• Point F = density independent limiting factors
cause a sudden crash or decline in population.
Scots Pine J-Curve
• Point D = deceleration phase
• Population growth slows down
• Point E = equilibrium
• Number of births equals the number of deaths.
May not last long due to changes in birth and
death rates
• Point G = the
population fluctuates
around the carrying
capacity
• Limiting factors that produce the S-curve are
density dependent
• competition, predation, disease
• An S-curve results when a population’s density is
somehow controlled so that it can become
somewhat stable.
Predator-Prey Relationships
• The prey population increases when there are
few predators and lots of food
• Now the predator has lots of food, so its
population will increase
Predator-Prey Relationships
• As the predator population increases, there is
more predation and competition, so the prey
population decreases
• Now the predators have less food, so their
population decreases
• Notice that:
• The two population curves follow the same shape
• The peaks and valleys of the predator curve trail the
peaks and valleys of the prey curve.
• The density of each population is dependent on
the density of the other.
• The predator’s population curve occurs a little
behind the population curve of the prey.
• The number of different species in an
ecosystem is called the biodiversity.
• Reducing biodiversity can cause a “domino
effect”
• can lead to a collapse
of an entire food web.
Food Web Stability
• In some food webs, the populations in the web
can survive if one species is removed. Other
populations can fill in as prey or predator species.
• A food web with more biodiversity is…
• less likely to collapse
due to the removal of one
species.
• There is an estimated 5 million to 30 million
species living on earth
• Why is the estimated range so large?
• Most living species are
microorganisms and tiny
invertebrates
• Species are constantly
evolving and going extinct
Quiz
1. A group of interacting populations of different species that
2.
3.
4.
5.
6.
7.
8.
occur together at the same place and time is known as a
_______________.
An organism’s particular role in an ecosystem is known as
it’s _______________.
What process do producers use to make food?
What are heterotrophs?
Give an example of a simple food chain. Identify the
producer, primary consumer, secondary consumer, and
tertiary consumer.
True or False: Each step in the food chain is a trophic level.
What is “carrying capacity”?
True or False: Population Growth= (births+emigration) –
(deaths+immigration)
Quiz
1. A group of interacting populations of different species that
occur together at the same place and time is known as a
_community___.
2. An organism’s particular role in an ecosystem is known as
it’s ___niche_____.
3. What process do producers use to make food?
Photosynthesis
4. What are heterotrophs?
Organisms that feed on other organisms to get energy.
Quiz
5. Give an example of a simple food chain. Identify the
producer, primary consumer, secondary consumer, and tertiary
consumer.
Corn, grasshopper, lizard, snake
6. True or False: Each step in the food chain is a trophic level.
7. What is “carrying capacity”? the maximum population of a
species supported by the environment
8. True or False: Population Growth= (births+emigration) –
(deaths+immigration)
Population Growth= (births+immigration) –
(deaths+emigration)
Scots Pine J-Curve
• Limiting factors that produce the S-curve are
density dependent
• competition, predation, disease
• An S-curve results when a population’s density is
somehow controlled so that it can become
somewhat stable.
• Point D = deceleration phase
• Population growth slows down
• Point E = equilibrium
• Number of births equals the number of deaths.
May not last long due to changes in birth and
death rates
• Point G = the
population fluctuates
around the carrying
capacity
Frog S-Curve
• Predators and prey will often have a relationship
described as delayed density dependence.
• The density of each population is dependent on
the density of the other.
• The predator’s population curve occurs a little
behind the population curve of the prey.
• This happens because the number of predators
that survive and reproduces depends on the
number of prey available for consumption
• As the population of prey increase, the population
of predators also increases.
• But, this causes a decrease in the population of
prey and then a
decrease in the
population of
predators.
Predator-Prey Relationship
What are
some
factors that
have
caused the
human
population
to
skyrocket
in the past
200 years?
Better
technology
Modern
medicine
Public
health
Population Histograms
• Population distribution according to age
• Useful to show how many organisms there are of a
certain age within a population
• Can tell us how the population will likely change in the
future
Compare males vs. females in a
population
Compare different age
groups in a population
We can use age-structure diagrams to compare
populations of different countries.
Population Histograms
• Populations along the horizontal axis
• Age along the vertical axis
• Graph is drawn with horizontal bars
• Each bar represents the number of organisms of a certain
age group. There are as many bars
as age groups.
• There is one side for males and
one side for females.
Population Histograms
• An age-population histogram shows a snapshot of
organisms, both male and female, that fall into categories
of age. While the data represented is for only a particular
instant in time, the shape of the distribution allows us to
predict if the population is increasing, decreasing or
steady.
Increasing Population Histogram
• Shaped like a pyramid with a wide
base.
• Wide base=lots of young organisms
to replace the older ones who die off.
• The population increases since there
are fewer older organisms and many
more being born
Decreasing Population Histogram
• Widest part in the middle section.
• Few young organisms to replace
the older organisms as they die
off.
• In later years, there will be fewer
organisms to reproduce and
supply offspring needed to
replace those which are now
young.
• The population decreases.
Steady Population Histogram
• Reproducing organisms are
simply replacing themselves.
• Since there are as many
organisms being born as are
dying, the population remains
steady.
Let’s review...
1. What is the most populated age group in this population?
2. Predict what age group will be the most populated in 15
years.
3. About how many children in this population are under the age of 5?
How many are female?
Let’s review...
1. What is the most populated age group in this
population?
The most populated age group is those between 20
and 24 years in age.
Let’s review...
2. Predict what age group will be the most populated in 15
years.
Assuming that there is not a major growth period in
this population in the next 15 years, the group that is
currently 20-24 years old will be in the 35-39 age
group.
Let’s review...
How many of them are
female?
Looking on the left side in
the 0-4 age bracket, about
6% of those under age 5
are female.
3. About how many children
in this population are
under the age of 5?
Approximately 12.5% of
the population is 0-4 years old.
Canada Age Structure
• In 2030, do
you think the
population will
be growing or
shrinking?
Why?
• In 2030, do
you think the
population will
be growing or
shrinking?
Why?
Shrinking. The
population is
aging and there
are less young
people to
reproduce.
• What are
some issues
that Canada
faces in the
future?
• What are
some issues
that Canada
faces in the
future?
• Will need to
provide more
health care for
aging
population
$$$
• http://ed.ted.com/lessons/population-pyramids-powerful-
predictors-of-the-future-kim-preshoff
Population Growth of Canada
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