What is Ecology?
scientific study of interactions among organisms and between organisms and their environment
Biosphere
Combined portions of the planet in which all of life exists, including land, water and air or atmosphereExtends from 8 kilometers above Earth’s
surface to 11 kilometers below the surface of the ocean
Interactions and Interdependence
Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live
Levels of OrganizationIndividual: interactions between an organism and
its surroundings cottontail rabbit
Population: groups of individuals that belong to the same species and live in the same areagroup of cottontail rabbits
Levels of OrganizationCommunities: different populations that live
together in a defined area rabbits, coyotes, ravens, lizard
Ecosystem: collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment rabbits, coyotes, ravens, lizard, rocks, dirt,
climate, water
Levels of OrganizationBiome: group of ecosystems that have the same
climate and dominant communities desert, tundra, tropical rain forest
Biosphere: planet Earth
Ecological MethodsThree approaches to ecological research:
Observing: Use of 5 senses to ask ecological questions
Experimenting: Used to test hypotheses artificial environment in a lab within natural ecosystems
Ecological Methods
Modeling: Used to gain insight into complex phenomena such as the effects of global warming
may include mathematical formulas based on data collected through observation and experimentation
predictions tested by further observations and experiments
Energy Flow
Energy flows from the sun or inorganic compounds to producers.
Consumers eat producers to get energy. The primary source of energy on Earth is the sun!!
Producers
Autotrophs – “self feed” Use sunlight to create carbohydrates via
photosynthesis Ex – Plants, algae and some bacteria Some bacteria create organic compounds from
inorganic chemicals – ChemosynthesisLive in remote places.
Consumers
Heterotroph – “Different food”Must eat to obtain energy.Ex – animals, fungi, some protists
Types of Heterotrophs Herbivore – eats plants Carnivore – eats animals Omnivore – eats plants and animals Detritivore – eats detritus (plant and animal
remains)Ex- snails, crabs, earthworms
Decomposer – breaks down organic matterEx – bacteria and fungi
Feeding Relationships
Energy flows through an ecosystem in one direction, from the sun or inorganic compounds
autotrophs (producers) various heterotrophs (consumers).
Food Chain
A series of steps in which organisms transfer energy by eating and being eaten.i.e. Wheat mouse snake hawk
Food Web
Network of complex interactions formed by the feeding relationship among the various organisms in an ecosystem.
Trophic Levels
Each step in a food chain or food web1st level = producers2nd, 3rd, or higher levels = consumers
Usually no more than 5 levels because 90% of energy is lost at each level.
Ecological Pyramid
A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.
Energy, biomass, and population numbers can all be represented by a pyramid.
Cycles of Matter
Recycling in the BiosphereMatter is recycled within and between
ecosystems.Matter moves through an ecosystem in
biogeochemical cycles.
Nitrogen Cycle
78% of Earth’s atmosphere is Nitrogen gas = N2
Nitrogen containing products:Ammonia (NH3)
Nitrate ions (NO3-)
Nitrite ions (NO2-)
Nitrogen is needed for protein and nucleic acid synthesis
Nitrogen CycleConverting nitrogen gas into ammonia is called
nitrogen fixation.Only certain types of bacteria can do this.Plants use the converted products (NH3, NO3- ,&
NO2-) to make plant proteins.
Some bacteria convert nitrates into nitrogen gas (denitrification).
Phosphorus Cycle
Phosphorus is important for the formation of DNA and RNA molecules.
Phosphorus is not very common and does not enter the atmosphere, instead it is found mostly on land in rock and soil.
Primary Productivity
The rate at which producers create organic matter. Determines the size of the community. Limited by availability of nutrients.
Land – phosphorus (P), nitrogen (N), potassium (K)Marine – nitrogenFresh water - phosphorus