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.

What is an Ecosystem?• Interacting groups of

Species and their environment

• Consists of both biotic and abiotic factors

Biotic Factors: Living things Ex: Birds, tiger, bees, etc.

Abiotic Factors: Non Living things

Ex: water, oxygen, rocks, etc.

Abiotic Vs. Biotic Factors

Rocks: Abiotic

Temperature: Abiotic

Weather: Abiotic

Flowers/Plants: Biotic

Animals: Biotic

Who’s Who in an Ecosystem?

AUTOTROPHIC / PRODUCER:

HETEROTROPHIC / CONSUMER:

DECOMPOSER –

organisms that make their own energy. EX: plants, algae, certain bacteria

organisms that consume their own food for energy. EX: animals

organisms that breaks down organic substances EX: certain bacteria, fungi, worms

Type of Consumers

• Herbivore – an organism that gets its energy by consuming plants.= primary consumers

• Carnivore – an organism that gets its energy consuming meat. = second consumers & tertiary consumers

• Omnivore – an organism that gets its energy by consuming both plants and meat.= secondary consumers & tertiary consumers

• Detritivore- organisms that eat dead/rotting organisms– EX: worms, vultures, & arthropods

Can an organism be classified as both a consumer and a

producer? Why or why not?

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Because animals eat at different trophic levels, most ecosystems have paths of energy that are not linear

Fig. 31.2

A complicated path of energy flow is called a food web

Trophic Level (feeding/energy level)- consists of all organisms feeding at the same energy level

Trophic Level (feeding/energy level)- consists of all organisms feeding at the same energy level

Energy in an Ecosystem

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.

ENERGY FLOWS THROUGH THE SYSTEM & NUTRIENTS CYCLE

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.

Energy transferred from the sun to the autotrophs and between consumers varies between ecosystems

ENERGY PYRAMID

Ideally 10% is transferred from one trophic level to the next.

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.• Not all food that’s eaten is absorbed by & used• There’s a lot of cellular respiration going on at all

levels for use in cellular activities.

What is Biomass?

The total mass of organic matter & is expressed in g m-2 yr-1 (grams per

meter squared per year)

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%.

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.

SummaryTake 5 minutes and summarize what you have learned about energy transfer & nutrients in an ecosystem.

•The ultimate source of energy (in most ecosystems) is the sun, which only 1% is captured by plants. •Energy and nutrients are passed from organism to organism through a food chain/web as one organism consumes another.•A majority of the energy (90%) is used by an organism and released as heat, until death, then decomposers remove the last energy from the remains of the organism.•Energy & Matter are not created nor destroyed, only transferred. •Inorganic nutrients are recycled, thanks to decomposers.•Energy is never recycled in an ecosystem, but its ultimate fate is heat.

• What is this interrelationship called?• How is this different than a food chain?• What do the lines represent?• How would you determine which organism(s) was an autotroph?

Create your own FOOD WEBDraw a food web with nine organisms. You must have one of each of the terms below. Label what each organism is (they may be more than one, so put all that they are):

•Herbivore

•Carnivore

•Omnivore

•Detritivore/Decomposer

•Autotroph/Producer

•Heterotroph

•Primary Consumer

•Secondary Consumer

•Tertiary consumer

Pick a food chain (highlight it) & calculate the energy each organism holds. Let’s say that the sun is shining down 17 million kJ of energy.

Your food chain should include at least one producer, one primary consumer, and one secondary consumer.

Food Web Questions

• Can organisms eat at more than one trophic level? If so, give an example.

• Which organisms eat at every trophic level?• What would happen if one of the organisms

were removed or exterminated?• Which organism’s removal would cause the

greatest impact? Explain why.

Time for The Biology Lab Bench

http://www.phschool.com/science/biology_place/labbench/lab12/intro.html

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

BIOGEOCHEMICAL CYCLES

AKA Nutrient cycles

We are going to divide up into 4 groups.

Each group is in charge of one cycle.

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.• Human influences

Water Carbon Nitrogen Phosphorus

Carbon PhosphorusNitrogen

Carbohydrates Proteins Lipids Nucleic Acid

TheWaterCycle

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.

• atmospheric fixation by lightning & rain • biological fixation by certain microbes • industrial fixation by humans

There are three processes responsible for most of the nitrogen fixation in the biosphere:

Atmospheric Fixation

• Taking atmospheric nitrogen (N2) and converting into usable forms of nitrogen (ammonium- NH4 or nitrate ions -NO3) by strong electrical bursts of energy- Lightning

• 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

• 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•Ammonia is absorbed into soil (mineralization)

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

-or within airtight cells in nodules of tissue on the roots of beans (legumes), aspen trees, & a few other plants.

-they live encased in cysts (bubble)

• 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).

Industrial Fixation

http://www.youtube.com/watch?v=AqE-0VPHWbM

Fertilizer plant

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Fig. 31.10 The nitrogen cycle

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 gasCan 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=U3SZKJVKRxQ

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?

• Which cycles have their main non-living reservoir in the atmosphere?

• What are the main forms found in living organisms for each nutrient?

phosphorus

Carbon and nitrogen

Carbon- carbohydrates & all other organic compoundsNitrogen- proteinsPhosphorus- nucleic acidsSulfur- amino acids

End for Unit 2 Exam

Greenhouse GasCarbon 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 enters the atmosphere

– Gases are transparent to light

• Most sunlight reflects off the Earth’s surface & bounces back out of the atmosphere.

• Some light energy is transformed into heat and warms up the surface of our planet.

• 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

The precautionary principle

• Ethical Theory that states:

– Action should be taken to prevent harm even if there is not sufficient data to prove that the activity will have severe negative consequences.

– If people wish to engage in an activity that may cause changes in the environment, they must first prove that it will not do harm.

How does this connect with global warming

• People who want to continue producing excess greenhouse gases should be made to prove there are no harmful effects before continuing.– Farmers, manufacturers, & transportation providers,

among others say if scientists are not 100% sure of the harmful consequences then why should they have to pay extra to be environmentally conscious.

• They will lose out to those who don’t comply

• Ideally, we as consumers would purchase products from environmentally friendly companies.

Consequences of a global temperature rise on arctic

ecosystems

More ice melting every year = polar bear pop. dwindles

Less snow = less algae growth. Algae is the most important producer in the arctic repercussions in the food webMore mosquitoes =

more pathogens

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

Interactions between Species• How can prey avoid getting captured?

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?

Symbiotic Relationships Symbiosis: 2 or more species

live together in a close long-term 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)

MutualismCooperative relationship which both

species benefit and neither harmed.

CommensalismOne species benefits and the

other is not affected

Honey Badger & Honey GuideHoney 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.

Predator-Prey Relationships

Competitive Exclusion Principle

• States that no two species in a community can occupy the same niche.

• If there are 2 species& they have a similar need for the same resources one will be excluded/ die off.

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/

mgbh.math.sp.penguincoat/estimation-from-random-sampling/en/

• The Mark & Recapture Method:– http://science.jburroughs.org/mbahe/BioA/

starranimations/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 reproductionDeath rate or mortality rate – the number of deaths in a period of timeLife 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

Invasive Species • Kudzu

– 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

• 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

• Factors affected by the density of a population that alter the population number

Density-Independent Factors

• 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.

• Factors not affected by the density of a population that alter the population number

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/lessons.htm