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Ecology What is ecology? • Ecology is the study of the interactions of living organisms with one another and with their physical environment (soil, water, climate…) • ECO = house • LOGY = the study of LEVELS OF ORGANIZATION Species Population Community Ecosystem Biome Biosphere Biosphere • The biosphere contains the combined portions of the planet in which all of life exists, including land, water and atmosphere. ENERGY FLOW • Every organism needs… …ENERGY!!! ENERGY FLOW • What are autotrophs? • Organisms that capture energy from the sun or chemicals to produce their own food. ENERGY FLOW • What is a producer? • Organisms that first capture energy (Autotrophs) • FIRST TROPHIC LEVEL ENERGY FLOW • During photosynthesis, autotrophs use light energy to power chemical reactions that convert CO2 and water into oxygen and high energy sugars (glucose). PRODUCERS LAND: Plants UPPER LAYERS OF OCEAN: Algae TIDAL FLATS/SALT MARSHES: Photosynthetic bacteria / cyanobacteria CHEMOSYNTHESIS • Chemosynthesis is the process by which organisms use CHEMICAL energy to PRODUCE carbohydrates. • Making food without sunlight! –Example: Bacteria ENERGY FLOW • If AUTOTROPHS are called PRODUCERS, because they make their own food, what are HETEROTROPHS called? CONSUMERS • Organisms that consume plants or other organisms to obtain energy. • All organisms that are NOT producers!!! (Heterotrophs) • Three categories – Primary – Secondary – Tertiary PRIMARY CONSUMERS • Herbivores –Eat plants or other primary producers • Examples – Cows – Horses – Rabbits – Some Insects • SECOND TROPHIC LEVEL SECONDARY CONSUMERS • Carnivores –Animals that eat animals –Examples: tigers, wolves, snakes • Omnivores –Animals that are herbivores and carnivores –Examples: bears, humans • THIRD TROPHIC LEVEL TERTIARY CONSUMERS • Carnivores that consume other carnivores • Known as “top carnivores” • Example: –A hawk that eats a snake –A lion that eats a hyena • FOURTH TROPHIC LEVEL DETRITOVORES • Decomposes organic material and returns the nutrients to the soil, water and air (making it available for other organisms). • Examples: mites, earthworms, snails, crabs DECOMPOSERS • Break down and absorb nutrients from dead organisms • They cause decay • Decomposition of bodies and wastes releases nutrients back into the environment to be recycled by other organisms. • Examples: bacteria, fungi SCAVENGERS • Do not kill their food—they search for a source of food that is already dead • “Clean-up” the ecosystem • Examples: buzzards FEEDING RELATIONSHIPS • Energy flows through an ecosystem in ONE direction: Sun (or inorganic chemicals) Autotrophs/Producers Heterotrophs/Consumers FOOD CHAIN • A food chain is a series of steps in which organisms transfer energy by eating or being eaten. • It is how energy moves through an ecosystem! FOOD WEB • A food web is a network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem. FOOD CHAIN vs. FOOD WEB • A food web will link together all of the food chains in a particular ecosystem… A terrestrial food chain A marine food chain TROPHIC LEVELS • A trophic level is a step in a food chain or food web. • Different organisms are on different levels depending on their source of energy. • Where does energy come from? SUN TROPHIC LEVELS 1st TROPHIC LEVEL Producers 2nd TROPHIC LEVEL Primary Consumers 3rd TROPHIC LEVEL Secondary Consumers 4th TROPHIC LEVEL Tertiary Consumers TROPHIC LEVELS • A consumer in a food chain depends on the trophic level below it for energy. ECOLOGICAL PYRAMIDS • An ecological pyramid is a diagram that show the relative amounts of energy or matter contained within each trophic level of a food chain or food web. ECOLOGICAL PYRAMIDS • Only part of the energy stored in a trophic level is passed on to the next because organisms use much of the energy they con ENERGY PYRAMID • All energy originates from the sun (or inorganic chemicals). • Sunlight (radiant energy) is converted to digestible energy by plants during photosynthesis. ENERGY PYRAMID • When the plants are eaten, the energy is transferred to animals to sustain life. • Energy is transferred up the food chain. Tertiary Consumers Secondary Consumers Primary Consumers Producers THE RULE OF TENS • Only 10% of the energy in a trophic level is passed on to the next level…90% of the energy is lost—where does it go? • Given off as HEAT!! BIOMASS PYRAMID • Biomass is the total amount of living tissue within a trophic level. • Represents the amount of potential food available at each trophic level. PYRAMID OF NUMBERS • Shows relative number of individual organisms at each trophic level. LIMITATIONS OF TROPHIC LEVELS Why can there not be too many links to one food chain? • Each trophic level can support about one-tenth the amount of living tissue as the level below it, because only 10% of the energy is passed up!!! A few more things… HABITAT • The area where an organism lives • Includes both biotic and abiotic factors Biotic vs. Abiotic Biotic • Bio- means: life • Tic- means: pertaining to Biotic factors are the living organisms in a habitat! Abiotic • Bio- means: life • Tic- means: pertaining to • A- means: no, not Abiotic factors are all the physical aspect of a habitat! Examples: soil, water, weather Abiotic Factors •Water •Air •Soil •Heat •Light