EcologyIB Biology

Modified from Fernanda Silva – Teacher at Chapel School

Ecology

The study of living organisms in the natural environment, how they interact with one another and how the interact with their nonliving environment

Levels of organization

atoms

molecules

organelles

cells

organs

tissues

systems

organism

species

population

community

ecosystem

biosphere

ECOLOGY

Species

A group of organisms that can interbreed and produce fertile offspring.

Great White Pelican Pelecanus onocrotalus

Population

A group of organism of the same species which live in the same habitat at the same time where they can freely interbreed

Habitat: the environment in which a species normally lives or the location of a living organism

The black-veined white butterfly

(Aporia crataegi) mating

Community

All the populations of the different species living and interacting in the same ecosystem

7-spotted lady bird

(Adephagia septempunctata)

Bean aphids

(Aphis fabae)

Red ant

(Myrmica rubra)

Broom plant

(Cytisus scoparius)

Ecosystem

Community (Biotic) interacting with environment (Abiotic )

Components of an Ecosystem

Biotic Factors: living or once living organisms

Abiotic Factors: nonliving factors that have an effect on living things

Examples:

- Water: organisms have water in their bodies (50-95%) and chemical reactions need water to happen.

- Soil: type of soil determines which plants and other organisms live in that location

- Light and Temperature: affect photosynthesis (plant growth is limited to amount of sunlight)

Energy + CO2 + H2O → C6H12O6 + O2

Energy and Organisms

Autotrophs: organisms which can synthesize their own complex, energy rich, organic molecules from simple inorganic molecules (e.g. green plants synthesis sugars from CO2 and H2O; bacteria in deep sea vents doing chemosynthesis) - PRODUCERS

Heterotrophs: organisms who must obtain complex, energy rich, organic compounds form the bodies of other organisms (dead or alive).

Ex: CONSUMERS and DECOMPOSERS (saprotrophs and detritivores)

Decomposers

Detritivores: heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, large scavengers). Ingest first, then digest.

Saprotrophs: heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria). Digest first, then absorb.

Earthworm(Lumbricus terrestris)

Chanterelle

(Cantherellus cibarius)

Consumers

Omnivore: eats both plants and animals

Carnivore: meat eater

Herbivore: plant eater

Food Chains

Sequence of relationships between trophic levels.

Show the flow of energy from the SUN to the heterotrophs

Trophic level: an organism’s feeding position in a food chain

Producers: essential to every single food chain

Food Web Shows the feeding relationships in a

community. Arrows show the flow of energy.

Generate a food web: http://coolclassroom.org/cool_windows/home.html

Growth (new biomass)

CellularrespirationFeces

100 J

33 J

67 J

200 J

Plant materialeaten by caterpillar

How much is available to the caterpillar’s predator?

Energy and Nutrients

Energy enters ecosystems as light and usually leaves as heat.

Nutrients do not usually enter an ecosystem and must be RECYCLED. Nutrients include: carbon, nitrogen, phosphorus, magnesium...

The Carbon Cycle

The Nitrogen Cycle

Pyramids of Energy

Biomass

Amount of dry matter in one organism Each bar represents: dry weight of all organisms

in one trophic level

Trophic level Dry weight(g/m2)

Tertiary consumers

Secondary consumers

Primary consumers

Primary producers

1.5

11

37

809

Populations

Factors that affect population size: Natality: the number of new members of the species due to reproduction

Mortality: the number of deaths

Immigration: members arriving from other places

Emigration members leaving the population

Pop. Change = (natality + immigration) – (mortality + emigration)

Population Growth

Exponential Phase: population increases exponentially because the natality rate is higher than the mortality rate.

Transitional phase: difference between natality and mortality rates are not as great, but natality is still higher so population continues to grow, but at a slower rate.

Plateau phase: natality and mortality are equal so the population size stays constant.

Carrying Capacity: the maximum population size that can be supported by the environment

Factors that limit the growth of a population

Limiting factors: prevents the continuing growth of a population in an ecosystem

The Greenhouse Effect Light from the sun has short wavelengths and can pass

through most of the atmosphere.

This sunlight warms the earth which in turn emits long wave radiation.

This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, water vapor, oxides of nitrogen and sulphur dioxide

The Greenhouse Effect

Natural and essential to life Human pollution is making it worse = causing

global warming Oxides of nitrogen: industrial processes, burning

fossil fuels, fertilizers Methane: cattle, waste disposal, natural gas leaks

CO2: burning fossil fuels

Consequences: Changes in climate = effects on the ecosystem Extinction Melting glaciers = rise in sea level Increase in photosynthetic rates

Sources of CO2There are four main 'pools' of carbon in the environment:

• Atmosphere     • Biosphere     • Sediments     • Ocean

There are a number of processes by which carbon can be cycled between these pools:

Photosynthesis:  Atmospheric carbon dioxide is removed and fixed as organic compounds (e.g. sugars)

Feeding:  In which organic carbon is moved from one trophic level to the next in a food chain

Respiration:  All organisms (including plants) metabolise organic compounds for energy, releasing carbon dioxide as a by-product

Fossilization:  In which carbon from partially decomposed dead organisms becomes trapped in sediment as coal, oil and gas (fossil fuels) 

Combustion:  During the burning of fossil fuels and biomass

In oceans, carbon can be reversibly trapped and stored as limestone (storage happens more readily at low temperatures)

Changes in atmospheric CO2

Changes in atmospheric CO2

Vostok Ice Core Data - CO2 vs Temperature (last 400,000 years)    

Precautionary Principle

Action should be taken to prevent harm even if there is not

sufficient data to prove that the activity will have severe

consequences

If people want to do activities that may cause a change in the

environment they must prove first it won’t do harm

We should take action now: reduce carbon emissions before

it’s too late

Should people invest money to reduce carbon emissions if we

are not 100% sure about the consequences of global warming?

More expensive to be eco-friendly

What should consumers do?

SL pg. 137

Artic Ecosystems:

- North America, Greenland, Iceland, Norway, Russia

- Loss of ice more ice is melting every year

- Climate change conveyor system is affected

- Rise in sea levels

- Melting of permafrost

- Increased decomposition CO2 and methane released into the atmosphere

- Increased success of pests/pathogens/mosquitoes

- Expansion of temperate species/reduced range for arctic species

- polar bears/seals/algae affected

- Disturbance of food chains

Sources:

http://www.sciencescene.com/Environmental%20Science/02TheEnvironment&Ecosystems/Successtion/Pond%20C.jpg