Ecology, 30/7/2012-2/8/2012

Some definitions:

Habitat: Place where organisms live, it must supply the needs of organisms.

Population: Group of living organisms in the same species.

Community: when all populations live together in a habitat and interact.

Niche: Role that each species plays in a community. Note that each species has a different role from another.

Ecosystem: Community+Abiotic factors interact.

Biome: Habitats with similar climate and plants.

There are 3 life supporting zones, namely the Lithosphere (crust of the Earth), Atmosphere (Gas) and Hydrosphere (Water). When they come together, they are known as...Biosphere.

These 3 components and non-living components are known as abiotic factors. 

Abiotic factors and Biotic (living factors) are needed for LIFE.

Abiotic Factors:

~Temperature: affects physiological activities of organisms

~Water: essential for life and organisms may have specially adapted features for survival in places with little water

~Light: Affects many organisms, not just plants.

~Oxygen: needed for all organisms for respiration.

~Salinity: amount of salt. Affects marine/aquatic organisms.

~pH level: level of acidity.

Biotic factors: the food, other organisms relationships.

1)Symbiosis: 

~Mutualism: Both organisms benefit from each other.

~Commensalism: 1 Organisms benefits, the other gains or loses nothing.

~Parasitism: 1 organism (host) is disadvantaged, other organism (parasite) benefits.

2) Competition for food and resources. Interspecific (other species) and Intraspecific (same species) competition

3) Predation

One population feeds on the other. The interaction between both organisms is necessary for the survival of the predator.


Predator-prey graph

Here's a typical food chain:

Producers->Primary Consumers->Secondary Consumers->Tertiary Consumers->Quaternary Consumers

Some more definitions: Detritivores

Decomposers--Recycle organic matter back to inorganic nutrients in ecosystems e.g. Fungi and Bacteria.

Detritus feeders--gain nutrients from dead animals and plants or animal waste products e.g. Termites, some bacteria, Beetles, Earthworms

Some pyramids that are used to obtain information:

Pyramids of numbers:

Number of the organisms top is the consumers and bottom is producers

Pyramids of dry mass:

Mass of organisms WITHOUT water.

Pyramids of energy:

Total energy used by organisms in a year.

Measured in: energy flow in kJ/m2/year