Transcript Ecology

Ecology
What is Ecology?
• Ecology is the study
of interactions
between organisms
and the living and
non-living
components of their
environment.
Levels of Ecology
BIOSPHERE-
broadest, most inclusive = the
thin volume of Earth and its atmosphere that
supports life.
ECOSYSTEMS-
includes all of the organisms
and the non-living environment found in a
particular place.
COMMUNITIES-
includes all the
interacting organisms living in an area.
POPULATIONS-
includes all the
members of a species that live in one
place at one time.
ORGANISMS-
simplest level= individual
• HABITAT- WHERE LIVING ORGANISMS LIVE.
• NICHE- A SPECIES WAY OF LIFE, OR THE ROLE THE
SPECIES PLAYS IN ITS ENVIRONMENT.
Who’s Who in an
Ecosystem?
Autotrophic & Heterotrophic
• A species method of getting nutrition.
– Autotrophic= make their own nutrients
– Heterotrophic= consume other organisms to gain
their nutrients
• Some unicellular species use both methods
– EX: Euglena
Heterotrophs are divided into different groups
depending on the organic material source and method
of consuming them
CONSUMERS:
• Are heterotrophs that feed on living
organisms by ingestion
DETRITIVORES• organisms that eat detritus ( dead parts
of plants, feces, various parts of dead
animals) by internal digestion
SAPROTROPHS –
• obtain organic nutrients from dead organic
matter by external digestion.
– Secrete digestive enzymes then absorb.
– EX: fungi and bacteria
• Also known as decomposers
ECOSYSTEMS
• Autotrophs & heterotrophs gain inorganic
nutrients for the abiotic environment
– C, H, O, & N are needed by getting them from
compounds in the food
– There are other inorganic nutrients needed that
are obtained by the abiotic environment
• EX: calcium, potassium, and sodium
The niche concept
• Every organism has a specific role in their
ecosystem.
– Where the organism lives
– What and how it eats
– Its interactions with other species
• The habitat where the organism lives is within
tolerable levels/zone
– Ex: abiotic factors
EXTINCTION OF ONE SPECIES
RESOURCE PARTITIONING SPLITTING THE NICHE
Interactions between Species
Predator-Prey
Relationships
Symbiotic Relationships
Symbiosis:
2 or more species
live together in a close longterm relationship where at least
one of them benefits.
•
Examples:
Parasitism,
Mutualism
Commensalism
Parasitism-
one species feeds
on the other
species known as
a host.
(one benefits while the other
is harmed)
Mutualism
Cooperative
relationship which both
species benefit and neither harmed.
Commensalism
One
species benefits and the
other is not affected
Honey Badger
& Honey Guide
Honey Guide bird loves
honey but can’t break the
beehive to get to the honey.
He leads the Honey Badger,
who also loves honey, to the
bee hive. The honey badger
breaks open the beehive,
eats his fill and leaves the
rest of the honey for the
honey guide bird.
Brown Bear & Scavenging Gulls
The scavenging gulls wait for the bears to eat their fill of
salmon and when the bears leave the gulls devour
whatever is left.
Cowbirds & Forest
nesting birds
Cowbirds lay their eggs in the
nests of forest nesting birds &
the forest nesting birds often
raise cowbird young rather than
their own offspring.
Ant & Aphid
The ant strokes the aphid and the aphid secretes a type of
honeydew for the ant to eat. With the ant around the aphid,
the aphid is protected against predatory insects.
Mistletoe & Mesquite
Mistletoe seeds are dropped on the mesquite tree. The seeds
germinate & grow into the tree. The “roots” of the mistletoe
absorb water and nutrients from the mesquite tree.
Mimicry
• Resemblance of
a distasteful or
poisonous
species
http://www.youtube.com/watch?NR=1&v=t-LTWFnGmeg&feature=endscreen
Camouflage
• The ability to
blend in with the
environmental
surroundings
http://www.youtube.com/watch?v=LDhUzafXm8A
WHERE’S THE FOX?
Keystone Species
• A species that plays a critical role in maintaining
the structure of an ecological community and
whose impact on the community is greater than
would be expected based on its relative
abundance or total biomass.
• Without the keystone species, the ecological
community to which it belongs would be greatly
altered and many other species would be
negatively impacted.
Keystone Species
Watch video
Energy Flow- Understanding
• Most ecosystems rely on a supply of energy from the
sun
• Light energy is converted to chemical energy in carbon
compounds by photosynthesis
• Chemical energy is converted to kinetic energy in
muscle contractions.
– Chemical to electrical in nerve cells
– Chemical to heat energy in heat-generating adipose tissue
• Living organisms cannot convert heat to other forms of
energy.
Trophic Level
(feeding/energy
level)- consists of all
organisms feeding at
the same energy level
Energy in an Ecosystem
ENERGY FLOWS THROUGH THE SYSTEM & NUTRIENTS CYCLE
All organisms need energy to carry out essential functions, such
as growth, movement, maintenance & repair, reproduction
and thinking. To do these functions they need energy.
The amount of
energy an
ecosystem receives
& the amount that is
transferred from
organism to
organism has an
important effect on
the ecosystem’s
structure.
Heat loss
• Heat from cell respiration= warm body
• Eventually heat passes from hotter to colder
bodies, so…
– Heat produced in living organisms is eventually
lost to the abiotic environment
What is the 1st law of
thermodynamics?
Energy can be transferred, but it
cannot be created or destroyed.
How can this be true when we can
see the relationship between
producers and consumers in ecology
& the loss of energy along the way?
Because the energy lost is lost to the
biosphere earth, but it is kept within
the universe.
If nothing is lost, explain where the
energy goes when a piece of paper
is burned.
The matter becomes ash & smoke; and
the heat, which is the energy that used
to be held in the molecular bonds of the
paper is dispersed to the universe.
If nothing is lost, where does the food
energy go when you eat a meal?
Most of the energy is lost as heat during
cell respiration and the matter is
converted into the molecules of your
body or discarded as feces.
If energy is lost from the biosphere
constantly as heat into the atmosphere,
where does the replacement energy
come from to keep the energy flow of
each ecosystem going?
There is a constant supply of energy
from the sun.
What is Biomass?
• The total mass of a group of organisms.
This includes: cells & tissues including
carbohydrates & other carbon
compounds
• It is expressed in g m-2 yr-1 (grams per
meter squared per year)
• Ecologists can measure the amount of
energy added per year by groups of
organisms to their biomass
Biomass
has energy
When ecologists measure this, they find….
The energy added to
biomass in each successive
trophic level is less.
The tiers get smaller as
you move up the trophic
levels because only a
small portion of the
energy in the biomass
of organisms in one level
will ever become part of
the next trophic level.
Ideally 10% is transferred from one
trophic level to the next but the amount
lost is variable.
Energy transferred from the
sun to the autotrophs and
between consumers varies
between ecosystems
Why don’t organisms from one trophic level get
the same amount of energy from the organisms
of the trophic level below them?
• Not all of the organism is consumed which then gets
passed on to the detritivores & saprotrophs.
• Not all food that’s eaten is digested & absorbed. Some
material passes through & comes out in feces. This
passes energy to the detritivores & saprotrophs
• There’s a lot of cellular respiration going on at all levels
for use in cellular activities which is then lost as heat.
What is going on here?
How do you measure biomass in a
trophic level?
•
•
•
•
Measure the total area of the ecosystem
Divide into small grids
Choose one plot to sample
Measure the size of each plant species, including trees
(height & diameter).
• Cut down all the trees & vegetation on the plot.
• Dry all of the plant samples
• Use a mathematical model to show the relationship
between weight & height of each plant species & its
biomass.
How do you measure biomass in a
trophic level?
• Sample the other plots by measuring the size & height
of plants
• For animals, set traps; weigh & measure. Use tables to
determine their biomass.
• Average the data for all species per plot
• Multiply the average per plot by the number of plants in
the ecosystem to discover the biomass of the entire
ecosystem.
• Repeat procedure seasonally or annually to study
changes over time.
What percent of the biomass(total mass of a group of organisms) in the
forest community represented above is tied up in the shrub layer?
Give your answer to the nearest whole number.
First, 14,100 KJ/m2 is 74.2 percent of the total accumulated
biomass, so the shrubs would possess 25.8 percent or 26% of
the total biomass.
A more complex pathway to the same answer is as follows:
Energy accumulated as biomass is 1.9 x 104 KJ/m2 or 19,000
KJ/m2 and is distributed among the tree layer, shrub layer, and
herb layer. The energy accumulated as biomass in the tree
layer is 1.3 x 104 KJ/m2 or 13,000 KJ/m2, and the energy
accumulated as biomass in the herb layer is 1.1 x 103 KJ/m2 or
1,100 KJ/m2. Together, the energy accumulated as biomass in
the tree and herb layers is 13,000 + 1,100 KJ/m2. Subtracting
this amount from the total of 19,000 KJ/m2 leaves 4,900 KJ/m2
energy accumulated as biomass (“tied up”) in the shrub layer.
This percentage of the total can be calculated as 4,900 KJ/m2
/19,000 KJ/m2 = .257 or 26%.
Let’s look at a chart and answer
questions
Rates of
succession
BIOGEOCHEMICAL CYCLES
AKA Nutrient cycles
We are going to divide up into
groups.
Each group is in charge of one cycle
(we may have duplicate cycles).
Water
Carbon
Nitrogen
Phosphorus
What to focus on:
•
•
•
•
Importance of each chemical
Forms in which each chemical is available to organisms.
Major reservoirs for each chemical
Key processes that drive the movement of each
chemical through its cycle.
• Fastest?
• Slowest?
• Human influences
• Good?/Bad?
Carbon
Carbohydrates
Nitrogen
Proteins
Lipids
Phosphorus
Nucleic Acid
The
Water
Cycle
Summary of The Hydrological Cycle
• http://www.epa.gov/safewater/kids/flash/flash_
watercycle.html
• Song of the Hydrological Cycle:
– http://www.youtube.com/watch?v=okZBiy_IdBA
75% of Earth’s surface is covered with ocean.
25% of the surface is land (7 continents).
The process by which
atmospheric nitrogen is
converted to ammonia or
nitrates.
• Important nutrient in
the ecosystem
• Used to make organic
molecules such as:
• Amino acids
• Proteins
• DNA
• Moves slowly through
the cycle
Where can Nitrogen Be
Found?
• Stored in reservoirs:
• living and dead plants, animals, soils, &
water.
• Main reservoir is the atmosphere
Gas = N2 (dinitrogen) ~80%
• Unfortunately, most organisms are unable to use
nitrogen in the atmospheric state, N2.
• The N2 must be “fixed”: this is known as nitrogen
fixation.
Fixation is the process of combining
nitrogen with oxygen or hydrogen.
There are three processes responsible for most
of the nitrogen fixation in the biosphere:
• atmospheric fixation by lightning & rain
• biological fixation by certain microbes
• industrial fixation by humans
Atmospheric Fixation
• Taking atmospheric nitrogen (N2)
and converting into usable forms
of nitrogen (ammonium- NH4 or
nitrate ions -NO3) by strong
electrical bursts of energyLightning
• Lightning storms:
– Lightning breaks apart the
nitrogen and combines it
with oxygen, then dissolves
it in water.
• This produces an acid
that falls to the earth as
rain= Acid Rain
(Nitrates).
–This is taken up by
plants and made into
proteins
How Do Animals Get
Nitrogen?
• Animals consume plants or other animals
that contain molecules composed partially
of nitrogen
• Nitrogen then reenters the ecosystem
through:
• Animal excretion
• Decomposition by detritovores and decomposers
• When animals die, the
animals decompose
and the nitrogen goes
into the soil through
their waste
• This is called
“mineralization”
• The nitrogen from the
waste is converted to
ammonia
Biological Fixation
•Ammonia is absorbed into
soil (mineralization)
• Bacteria converts the ammonia to nitrates,
this is called “nitrification” or biological
fixation
– The nitrates are either taken up by plants,
dissolved into water, or remain in the soil.
• Denitrification - returned to the
atmosphere
BIOLOGICAL FIXATION:
There is a bond that has to be broken with
the N2 and some bacteria are able to break
this bond.
These bacteria cannot be exposed to oxygen
-they live encased in cysts (bubble)
-or within airtight cells in
nodules of tissue on the
roots of beans
(legumes), aspen trees,
& a few other plants.
Industrial Fixation
• Under great pressure,
at a temperature of
600°C, and with the use
of a catalyst,
atmospheric nitrogen
and hydrogen can be
combined to form
ammonia (NH3).
Fertilizer
plant
http://www.youtube.com/watch?v=AqE-0VPHWbM
Fig. 31.10 The nitrogen cycle
Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
The Carbon Cycle
MAIN RESERVOIR OF CARBON IS IN THE
ATMOSPHERE.
Carbon Fixation
• Autotrophs convert CO2 into carbohydrates &
other carbon compounds (ex: lipids)
• This has the effect
of reducing the
CO2 in the
atmosphere
Carbon Cycle
• Photosynthesis - takes carbon dioxide and water
and produces carbohydrates and oxygen.
• Respiration - takes carbohydrates and oxygen
and combines them to produce carbon dioxide,
water, and energy.
• Consumption of Carbohydrates – eating
plant and animal material gives the
consumer carbohydrates (such as glucose)
• Combustion/Fossil Fuel burning- the
release of CO2 and CO from a chemical
reaction (coal, oil, and natural gas)
• Volcanic Eruptions- as gases and
magma spew from a volcano it
releases large amount of CO2 into
the air
200 million tons of CO2 is released annually by
land and water volcanoes
Human
activity
releases ~28.6
billion tons
• Organic Decay- the
decomposition of once living
organism releases CO2
– Reformation of Fossil Fuels- as fossils release
carbon it is used to form new fossil fuels, this
process takes a very, very, very long time
Carbon Dioxide in Solution
• In aquatic habitats carbon dioxide is
present as a dissolved gas and hydrogen
carbonate ions
– CO2 is soluble in water
Can remain as dissolved gas
Can combine with water to form
carbonic acid (H2CO3)
It can dissociate to form
hydrogen and hydrogen
carbonate ions
This is why CO2 can
reduce the pH of water
• Creation of Limestone - Carbon dioxide
dissolves readily in water. Once there, it
may precipitate (fall out of solution) as a
solid rock known as calcium carbonate
(limestone). This is how reefs are made.
Dissolved carbon dioxide is also used by
marine biota during photosynthesis.
Carbon Cycle
• http://www.youtube.com/watch?v=U3SZKJ
VKRxQ
Carbon Cycle Questions
•List three fossil fuels & describe how they are made.
•State 2 locations Carbon travels to once it’s in the atmosphere.
•State 3 ways humans release carbon into the atmosphere.
•State 2 ways carbon is released into the atmosphere naturally.
•What is a carbon footprint? Why do we care so much about this?
•State some ways in which you have already or that you could try to
reduce your carbon footprint.
•Give some possible explanations as to why people don’t try to reduce
the amount of carbon they release into the atmosphere.
Phosphorus Cycle
Biological Importance
• Helps make:
– Nucleic acids
– Phospholipids
– ATP
How does it work?
• Erosion of rocks (biggest contributor)
– Adds phosphate to soil and leech into the
groundwater & surface water.
– Taken up by producers
– Eaten by consumers (plants)
– Returned to the soil by decomposition & excretion
Post Activity Questions
• Which element is never found in the
atmosphere? phosphorus
• Which cycles have their main non-living
reservoir in the atmosphere?
Carbon and nitrogen
• What are the main forms found in living
organisms for each nutrient?
Carbon- carbohydrates & all other organic
compounds
Nitrogen- proteins
Phosphorus- nucleic acids
Sulfur- amino acids
Time for The Biology Lab Bench
http://www.phschool.com/science/bi
ology_place/labbench/lab12/intro.ht
ml
Some of the factors that affect the
amount of oxygen dissolved in water
• Temperature: As water becomes warmer, its ability to hold
oxygen decreases.
• Photosynthetic activity: In bright light, aquatic plants are able
to produce more oxygen.
• Decomposition activity: As organic material decays, microbial
processes consume oxygen.
• Mixing and turbulence: Wave action, waterfalls, and rapids all
aerate water and increase the oxygen concentration.
• Salinity: As water becomes more salty, its ability to hold
oxygen decreases.
Primary productivity
• A term used to describe the rate at which plants
and other photosynthetic organisms produce
organic compounds in an ecosystem. There are
two aspects of primary productivity:
– Gross productivity: the entire photosynthetic
production of organic compounds in an ecosystem.
– Net productivity: the organic materials that remain
after photosynthetic organisms in the ecosystem have
used some of these compounds for their cellular
energy needs (cellular respiration).
Measuring net productivity
• Measure oxygen production in the light, when
photosynthesis is occurring.
• Measure respiration without photosynthesis
by measuring O2 consumption in the dark,
when photosynthesis does not occur.
Primary productivity can be measured
in three ways:
• The amount of carbon dioxide used
• The rate of sugar formation
• The rate of oxygen production
Greenhouse Gas
Carbon Footprints
The Greenhouse Effect
Is it a good thing or a bad thing?
The natural greenhouse effect
• The atmospheres ability to retain heat (a global
greenhouse.
• With the help of greenhouse gases:
– Water vapour
-methane
– CO2
-nitrogen oxides
How it works:
• Sunlight short wavelengths (UV) enter the atmosphere
– Some are absorbed by the ozone layer
– Most make it to earth
• A lot of this is converted to heat
• Longer wavelengths (infrared) are re-emitted from the
surface of the Earth.
– most of these are absorbed by the greenhouse gases
• Greenhouse gases retain some of the heat & trap it in
the atmosphere.
• End result: our atmosphere is warmer than outer space
Human Activity
• A rise in human activity & population has lead to
an increase in CO2 , nitrous oxide & methane
– All 3 have the ability to absorb heat which increases
the temperature causing:
• Increase in photosynthesis rates
• Various effects on ecosystems
• Extinction of certain species
• Melting glaciers & land ice
• Rise in sea level
What is this information telling us??
How the past temps and
carbon dioxide levels
have been obtained.
Consequences of a global
temperature rise on arctic
ecosystems
More ice melting
every year = polar
bear pop. dwindles
More mosquitoes =
more pathogens
Less snow = less algae
growth. Algae is the most
important producer in the
arctic
repercussions
in the food web
Conservation & Biodiversity
(first some terms)
• Indicator species:
– An organism used to assess a specific
environmental condition.
• Biotic index
– Compares the relative frequency of indicator
species.
• EX: multiply the number of a certain kind of organism
by its pollution tolerance rating. Each of these are
added to the others and divided by the number of
organisms in the habitat.
In situ conservation vs Ex situ
conservation
• In situ:
– May require active management of nature
reserves or national parks
•
•
•
•
Controlled grazing
Removal of shrub & trees
Limiting predators
Feeding the animals
– measures endangered species remaining in the
habitat to which they are adapted.
In situ conservation vs Ex situ
conservation
• Ex situ:
– Preservation of species outside their natural
habitat.
• It is the process of protecting an endangered species of
plant or animal outside its natural habitat.
PROPERTIES OF POPULATIONS
• POPULATION SIZE:
-difficult to measure
-if small and immobile it is easy
-more often than not populations are too
abundant, too widespread, and very mobile
-scientists must estimate the numbers in a
population
– EX: Random Sampling:
• If they need the population of oak trees in a 10km2 patch of
forest. They would count the number of oak trees in 1km2 &
then times it by 10.
– Catch Tag & Release…
If you want to compare populations
don’t go out & count everyone…
• Random sampling is what you need.
• The Quadrat method:
– http://www.pbslearningmedia.org/resource/mgb
h.math.sp.penguincoat/estimation-from-randomsampling/en/
• The Mark & Recapture Method:
– http://science.jburroughs.org/mbahe/BioA/starra
nimations/chapter40/videos_animations/capture_
recapture.html
PROPERTIES OF POPULATIONS
• POPULATION
DENSITY:
-measures how
crowded a population
is.
-expressed as the
number of individuals
per area or volume
– EX: US has a
population density of
30 people per square
kilometer or 30/km2.
• DISPERSION: spatial distribution of a
population
– 3 kinds:
Population Growth
• A J-Shaped
graph is
exponential
growth.
• Exponential
growth means
that as a
population gets
larger, it grows at
a faster pace.
•The initial increase is slow (small number or
individual reproducing), but rapidly increases (more
individuals reproducing)
What types of things
effect the numbers of a
population ?
What can effect the numbers in a
population?
Birth rate or natality – the number of new
members of the species
due to reproduction
Death rate or mortality rate – the number
of deaths in a period of time
Life expectancy- how long on average an
individual is expected to
live.
• Invasive/introduced species – an
organism that is not originally from the
environment it’s currently living in.
–Introduced by accident, for aesthetics,
economic benefit, or sport hunting
Invasive Species
• Ballast Water
– For cruise or cargos ships to
remain stable they take on
water from the ocean and store
it
– Likely the largest source of
exotic species introduction into
US ecosystems
• The zebra mussel has become a
serious problem. They kill local
species, damage harbors &
boats, and water treatment
plants
– $123 billion/year in clean up
• Kudzu
Invasive Species
– Purposefully introduced
into the US in the late
1800s for soil erosion
control
– Has since grown out of
control crowding out
native species across the
southeastern region of
America
http://www.youtube.com/watch?v=x5p37wpdFII&feature=fvst
• Limiting factors are factors that limit the
growth of the population.
•Ecologists have identified
two kinds of limiting factors
that are related to dispersal:
DENSITY-DEPENDENT FACTORS
DENSITY-INDEPENDENT FACTORS
Density-Dependent Factors
• Factors affected by the density of a
population that alter the population number
• Include: competition, predators, food,
disease, space & hormonal changes.
• These factors have an increasing effect as
the population increases
• Ex. in an overcrowded bee hive a
disease will spread faster than in one
that is much less crowded
Density-Independent Factors
• Factors not affected by the density of a
population that alter the population number
• Include: abiotic factors, such as volcanic
eruptions, temperature, storms, floods,
drought, chemical pesticides, and major habitat
destruction.
• All populations can be affected by these
factors, but small organisms with large
populations are the most vulnerable
• Ex. earthworms drowning in the fields
when it floods, severe winters kill all the
adult mosquitoes.
When locust populations become crowded
they produce hormones that cause them to
go into a migratory phase, where they take
off as a swarm and fly long distances to a
different habitat. What factor is
influencing this population density?
DENSITY-DEPENDENT
Limiting factors cause a Sigmoid (S-Shaped)
growth curve.
Causes of Exponential Growth
•
•
•
•
Plentiful resources such as food, water, space…
Little or no competition
Favorable abiotic factors such as temperature
Little or no predation or disease.
Causes for the transitional phase
• Increasing competition for resources
• Predators move into the area
• As numbers increase there is more chance for
disease to spread within a population due to
the limited space.
Causes of the plateau phase
• Increase numbers of herbivores leads to less
food which leads to fewer offspring.
• Predators & disease increase the death rate
• # of births + # of immigrations is balanced
with the # of deaths + # of emigrations
Under ideal conditions, a population naturally
increases until it overshoots the carrying
capacity. At this point, the environment can no
longer provide for the species. The population,
due to lack of resources, will begin to die out,
allowing the environment to recover. As the
environment recovers, the species population is
able to flourish once more. This leads to a
fluctuation between the prosperity of the species
and the prosperity of the environment (hence
the fluctuations in the graph). This type of
growth is called logistic growth.
Carrying Capacity (K) = the maximum number
of a population that a given environment can
support for an extended period of time.
This is the most stable number for a population
in a given environment (equilibrium for a
population).
What abiotic factors might affect
the distribution of plant species?
•
•
•
•
•
Temperature & water
Light
Soil pH
Salinity
Mineral nutrients
What abiotic factors might affect
the distribution of animal species?
•
•
•
•
•
Temperature
Water
Breeding sites
Food supply
Territory
If you want to study how the
distribution of plants in an ecosystem
is affected by abiotic factors…
• Let’s look at a sand dune community…
• Create a quadrant from the sea to the mature
dunes.
• In each quadrant count the number of chosen
plant species
• Measure abiotic factors.
It’s time for Population Dynamics
http://ats.doit.wisc.edu/biology/less
ons.htm