Ch. 18- Ecology - The Biosphere

What is Ecology? It is the scientific study of interaction among organisms and between organisms and their environment

Interdependence is the Key Ecology: –Greek oikos – house –Logos –study of

What is the Biosphere? The biosphere is the combined portions of the entire planet where life exists.

Levels 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. 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. 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 Organization

Ecological 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 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 Environment 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 Curve

Acclimation 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 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 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 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. 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 Relationships Energy flows through the ecosystem in one direction.

Food Chain

Food Web

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 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 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 cycle

Other 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.

Productivity 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.