Principles of Ecology: Relationships All living things form relationships with other living things Symbiotic Relationship – a relationship between organisms of two different species that live together in direct contact

Commensalism One organism benefits – The other is not affected Examples Spanish moss on a tree Barnacles on a whale Burdock seeds on a passing animal

Mutualism Both organisms benefit Acacia tree and ants (Pseudomyrmex sp.) – tree provides food for the ants and the ants protect the tree from animals that would eat the leaves Lichens: algae and fungus living together. Algae provides food (photosynthesis) and the fungus provides protection and attaches the lichen to the rock or wood where it lives.

Parasitism One organism benefits, the other is harmed Some live with in the host Tapeworms Heartworms Bacteria Some feed on the external surface of the host Ticks Fleas Mistletoe Most do not kill their host (at least not quickly)

Ecosystem Requirements #1 - Continuous supply of Energy #2 – A flow of energy from one population to another

Obtaining Energy Autotrophs - use energy from the sun or energy stored in chemical compounds to produce energy Heterotrophs – must consume their energy Herbivores Carnivores Omnivores Detritivore (AKA decomposers)

Herbivores Eat plants (autotrophs)

Carnivores Eat other heterotrophs Predators – kill their own food Scavengers – eat animals that are already dead

Omnivores Eat both autotrophs and heterotrophs (plants and animals)

Decomposers and Scavengers Decomposers – decompose organic matter and return nutrients to soil, water, and air. Scavengers consume dead organisms. Ex. fungus, bacteria

Energy Flows through an Ecosystem in a Complex Network of Feeding relationships called a FOOD WEB.

Food Chain: Single line of energy

Energy Pyramid The energy pyramid is made of several trophic levels A Trophic Level (or feeding level) is a group of organisms whose feeding source is the same number of steps from the Sun. Primary Producers (Autotrophs) are the First Trophic Level. Primary Consumers (Herbivores) are the Second Trophic Level. Secondary and Tertiary Consumers (Carnivores and Omnivores) are the Third and Fourth Trophic Levels. Most Animals feed at more than one Trophic Level.

Trophic Levels Energy is Lost or Used as it Flows through the Trophic Levels of an Ecosystem. Producers (Plants) absorb Energy from the Sun, but only about ½ of the Energy capture from the Sun becomes part of the Plants Body. The other ½ is used for Living and Growing or Lost as HEAT. At each Trophic Level, the Energy stored in an organism is about 1/10 that of the Level Below it. (10%).

Trophic Levels Because Energy diminishes at each successive Trophic Level, Few Ecosystems can contain more than 4 or 5 Trophic Levels. Organisms at Higher Trophic Levels, Large Carnivores, tend to be Fewer in number than those at Lower Trophic Levels, Producers.

Bioaccumulation Energy is not the only thing that is passed along through the food web. If contaminants are introduced at any level, those organisms that consume the contaminated food, will absorb the contaminants as well. Because the amount of energy required gets higher at each level, those organisms have to consume more and thus can accumulate higher levels of the contaminants in their bodies – bioaccumulation.

Example of Bioaccumulation Example – A pesticide that you put of your yard is consumed by the grasshoppers that live there. The partridge eats 10 grasshoppers. The hawk eats 3 partridges. If the grasshopper consumed 1 mg of the pesticide, the partridge ingested 10mg, and the hawk consumed 30mg.

Cycles of Matter Cycles of Matter are the movement of a particular form of matter through the living and nonliving parts of an ecosystem Since Earth is a closed system, it must continually cycle its essential matter. Matter changes form but is neither created nor destroyed; it is used over and over again in a continuous cycle. Organisms are an important part of this cycling system. Matter placed into biological systems is always transferred and transformed. Matter, including carbon, nitrogen, and water, gets cycled in and out of ecosystems.

Carbon Cycle Carbon is one of the major components of the biochemical compounds of living organisms (proteins, carbohydrates, lipids, nucleic acids). Carbon is found in the atmosphere and also in many minerals and rocks, fossil fuels (natural gas, petroleum, and coal) and in the organic materials that compose soil and aquatic sediments. Organisms play a major role in recycling carbon from one form to another in the following processes: Photosynthesis Respiration Decomposition Conversion of biochemical compounds

Carbon Recycling Processes Photosynthesis: Autotrophs take in carbon dioxide from the atmosphere and convert it to simple sugars. Respiration: Organisms break down glucose and carbon is released into the atmosphere as carbon dioxide.

Carbon Recycling Processes Decomposition: When organisms die, decomposers break down carbon compounds which both enrich the soil or aquatic sediments and are eventually released into the atmosphere as carbon dioxide. Conversion of biochemical compounds: Organisms store carbon as carbohydrates, proteins, lipids, and nucleic acids in their bodies. When animals eat, those compounds can be: used for energy converted to compounds that are suited for the predator’s body released to the atmosphere as methane and other gases

Carbon Recycling Processes Other methods of releasing stored carbon may be: Combustion: When wood or fossil fuels (which were formed from once living organisms) are burned, carbon dioxide is released into the atmosphere. Weathering of carbonate rocks: Bones and shells fall to the bottom of oceans or lakes and are incorporated into sedimentary rocks such as calcium carbonate. When sedimentary rocks weather and decompose, carbon is released into the ocean and eventually into the atmosphere.

Water Cycle Water is a necessary substance for the life processes of all living organisms. Water is found in the atmosphere, on the surface of Earth and underground, and in living organisms. The water cycle, also called the hydrologic cycle, is driven by the Sun’s heat energy, which causes water to evaporate from water reservoirs (the ocean, lakes, ponds, rivers), condense into clouds, and then precipitate back to water bodies on Earth. Organisms also play a role in recycling water from one form to another by: Intake of water into the organisms Transpiration Respiration Elimination

Water Recycling Processes Intake of water into the organisms: Organisms take in water and use it to perform life functions (such as photosynthesis or transport of nutrients). Transpiration: Plants release water back into the atmosphere through the process of transpiration (the evaporative loss of water from plants). Respiration: All organisms metabolize food for energy and produce water as a by-product of respiration. Elimination: Most organisms need water to assist with the elimination of waste products.