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BIG IDEA • The niche of an organism determines that organisms biotic interactions with other organisms including its feeding relationship, competition, & symbiosis PRODUCERS •aka autotrophs •make their own food from inorganic molecules and energy CONSUMERS •kinds of heterotrophs •organisms that cannot make their own food CONSUMERS HERBIVORES •aka primary consumers •organisms that eat only plants •vegetarians CONSUMERS CARNIVORES •aka secondary or tertiary consumers •organisms that eat herbivores and other carnivores •meat eaters CONSUMERS OMNIVORES •aka primary, secondary or tertiary consumers •organisms that eats producers and other consumers CONSUMERS SCAVENGERS •aka 1, 2, or 3 level consumers •organisms that eats dead organisms •usually does not hunt •may eat plants or animals •small aquatic ones often known as detritivores (i.e. crabs) DECOMPOSERS •kinds of heterotrophs •bacteria and fungi that consume the bodies of dead organism and other organic wastes A TROPHIC LEVEL is a layer in the structure of feeding relationships in an ecosystem. TROPHIC LEVELS producers = 1st trophic level consumers = 2nd trophic level consumers = 3rd trophic level consumers = etc… trophic level TROPHIC LEVELS Autotrophs are the sole point of entry for new energy into the ecosystem. A FOOD CHAIN is a series of energy (food) transfers between the trophic levels of an ecosystem Food chains start with producers. producer primary consumer secondary consumer tertiary consumer A FOOD WEB is a network of food chains representing the feeding relationships among the organisms in a more complex system Food webs include all the food chains in an ecosystem DIVERSITY & STABILITY Some ecologists think that an ecosystem with high diversity and a more complex food web is more stable. WHY? WHY? • An ecosystem with more food options will be more diverse because if one organism goes extinct than there are other options to eat. The increasing concentration of a pollutant in organisms at higher trophic levels in a food web. i.e. DDT Energy enters an ecosystem when producers use sunlight to make organic matter through photosynthesis. energy Consumers take in this energy when they eat producers or other consumers. energy energy Most of the energy that enters through organisms in a trophic level does not become biomass. WHY NOT? The total amount of organic matter present in a trophic level only about 10% of the energy entering one trophic level forms biomass in the next trophic level. Primary Production • The synthesis and storage of organic molecules during the growth and reproduction of autotrophs - Measured as the rate of formation of new material per unit of the earth’s surface and time • Standing crop biomass- amount of matter found in a given area at any point in time • Gross Primary Production (GPP)-refers to energy converted by photosynthesis • Net Primary Production (NPP)refers to energy left over after the plant has used some of this chemical energy for it’s own metabolic needs (ex. Growth, reproduction) -plant biomass is the physical manifestation of NPP NPP Global NPP • Global NPP is the amount of energy available to all heterotrophs • Turnover rates- change in standing crop biomass over time (low standing crop, high rate of production during a brief growing season) ex. Grasslands and oceans (surface) • Rates of production are determined by climate (temp./precip.) and nutrients • Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. Secondary Production • The conversion of assimilated energy into new tissue by heterotrophs -it is conceptually the same as the primary production or NPP of plants. • Organisms vary in how efficiently they can convert assimilated energy into secondary production due to widely differing metabolic requirements. • Homeotherms (warm-blooded)low net production efficiencies b/c they need to maintain a constant internal body temperature • Poikilotherms- organisms that do not regulate their temperatures internally; have a higher net production efficiency Pyramids of Biomass, Energy, and Numbers • A pyramid of biomass is a representation of the amount of energy contained in biomass, at different trophic levels for a given point in time • pyramid of numbers- represents the number of organisms in each trophic level Bottom-Up vs. Top-Down Control • bottom-up control, states that it is the nutrient supply to the primary producers that ultimately controls how ecosystems function - increase in food results in an increase in heterotrophs • top-down control, states that predation and grazing by higher trophic levels on lower trophic levels ultimately controls ecosystem function. - Increase in predators = fewer grazes resulting in more producers Mammals are heterodont: they have different types of teeth in their mouths. Other vertebrates are homodont: meaning they have all the same types of teeth. MOLARS PRE MOLARS CANINES INCISORS INCISOR MODIFICATIONS •enlargement to form chisels used for gnawing. i.e. rats, mice •incisors followed by a toothless gap (diastema) i.e. rabbits INCISOR CANINE What kinds of animals are these? INCISOR wolf CANINE bat CANINE MODIFICATIONS •for stabbing and holding prey •in herbs., often reduced in size or missing •may be weapons in displays or fighting •in many, larger in males than in females PREMOLARS • usually, but not always, slightly smaller and simpler than the molars •are deciduous, later replaced MOLARS • vary tremendously in size, shape, and function •permanent teeth