Ch. 18- EcologyCh. 18- Ecology

- The Biosphere- The Biosphere

What is Ecology?What is Ecology?

• It is the scientific study of interaction among organisms and between organisms and their environment

Interdependence is the KeyInterdependence is the Key

• Ecology:– Greek oikos – house

– Logos –study of

What is the Biosphere?What is the Biosphere?

• The biosphere is the combined portions of the entire planet where life exists.

Levels of OrganizationLevels of Organization

• To understand relationships within the biosphere ecologists ask questions abut events and organisms that range in complexity from a single individual to the entire biosphere

Levels, cont.Levels, cont.

• Species: a group of organisms so similar to one another that they can breed and produce fertile offspring.

• Populations: a group of individuals that belong to the same species and live in the same area.

• Communities: different populations that live together in a defined area.

Levels, cont.Levels, cont.

• Ecosystems: all the organisms that live in a particular place, together with their nonliving or physical environment.

• Biomes: a group of ecosystems that have the same climate and dominant communities.

Levels of OrganizationLevels of Organization

Ecological MethodsEcological Methods

• Observing

• Experimenting

• Modeling

Observing can be as simple as asking ecological questions or be more complex and form the first step in designing experiments and models.

• Experimenting is used to test hypotheses. This can be done n an artificial setting like a lab or within natural ecosystems.

• Modeling is used to gain insight into larger, more complex processes, such as global warming. Models are used to make predictions which may be tested by observations and experiments.

• Describe the ecological method shown in each picture that follows.

Ecosystem ComponentsEcosystem Components

• Biotic– All living things that

affect the organism

• Abiotic– Temperature– Humidity– pH– Salinity– Oxygen concentration– Amount of sunlight– Availability of Nitrogen– precipitation

Organisms in a Changing Organisms in a Changing EnvironmentEnvironment

• Each organism is able to survive within a limited range of environmental conditions.

• A graph of performance versus values of an environmental variable such as temperature is called tolerance curve

Tolerance CurveTolerance Curve

AcclimationAcclimation

• Some organisms can adjust their tolerance to abiotic factors such as temperature, or pH.

• This is NOT an adaptation. It occurs within the lifetime of the individuals. It is not a genetic change.

Control of Internal ConditionsControl of Internal Conditions

• Conformers– Don’t regulate their

internal condition– Change with the

environment– Internal conditions

only remain optimal IF environment is optimal

• Regulators– Use energy to control

their internal conditions.

– Internal conditions remain optimal over a range of environmental conditions.

Niche: the jobNiche: the job

• Generalists– Species with broad

niches can tolerate a range of conditions and use a variety of resources.

– Ex. Virginia opossum

• Specialists– Species with a narrow

niche– Ex. Koalas only eats

eucalyptus leaves.

Energy Flow in the EcosystemEnergy Flow in the Ecosystem

• Living systems need a constant input of energy.

• Main source of energy for life on earth is??

• Some types of organism rely on the energy stored in inorganic chemical compounds.

Energy Flow, cont.Energy Flow, cont.

• Autotrophs– Organisms that use

energy from the environment to make complex organic compounds

– Also known as producers

– Two types• Photosynthesis• Chemosynthesis

• Heterotrophs– Rely on other

organisms for their energy and food supply.

– Also known as consumers

• Types:– Herbivores– Carnivores– Detritivores– Decomposers.

Feeding RelationshipsFeeding Relationships

• Energy flows through the ecosystem in one direction.

Food ChainFood Chain

Food WebFood Web

What is a trophic level?What is a trophic level?

• Each step in a food chain or food web is a trophic level.

• Each trophic level depends on the level below it for energy

Ecological PyramidsEcological Pyramids

• Can be used to represent energy, matter or number of individuals at each trophic level

• Energy Pyramid: only 10% of the energy available at one trophic level makes it to another.

• Biomass Pyramid: represents all the living tissue (food) at each trophic level.

• Pyramid of Numbers: the number of individual organisms at each trophic level usually decrease as you go up the pyramid of numbers.

Cycles of MatterCycles of Matter

• Unlike the one-way flow of energy, matter is recycled in the biosphere.

• Elements , chemical compounds and other forms of matter are passed from one organism to another through biogeochemical cycles.

Water cycleWater cycle

Other Biogeochemical CyclesOther Biogeochemical Cycles

• Carbon - carbon is especially important because it is the key ingredient in all living organisms. Carbon is found in oceans, the air, and certain types of rock

• Nitrogen - All organisms require nitrogen to make amino acids which are used to build proteins.

• Phosporus - Unlike carbon nitrogen and oxygen, phosphorous does not enter the air, it remains mostly in rock, soil minerals, and ocean sediments. Phosphorous is of great biological importance for molecules like DNA and RNA.

ProductivityProductivity

• Primary Productivity: the rate at which organic matter is created by a producer.– Controlled by the availability of nutrients in the

environment– Limiting nutrient: the one nutrient that when

in short supply, will limit the primary productivity of the ecosystem.