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Goal Five The learner will develop an understanding of the ecological relationships among organisms. 5.01 Investigate and analyze the interrelationships among organisms, populations, communities, and ecosystems. o Students should be able to identify and describe symbiotic relationships o Mutualism Two species interact closely in a way that benefits both species Ants and acacia trees: ants live in the acacia thorns and eat their leaves, acacias benefit because ants protect them from predators and will even destroy other plants that shade the acacias from the sun Honeybees and other insect pollinators have a mutualistic relationship with many flowers. o Commensalism One organism benefits from the interaction and the other organism is neither helped nor harmed. the clown fish and sea anemone: the clown fish lives on scraps from the sea anemone’s meals. When danger threatens, it retreats into the sea anemone’s waving tentacles. Most fish are instantly paralyzed by the tentacles, but the clown fish seems to be immune to the sea anemone’s touch barnacles that live on the skin of whales or sea turtles barnacles benefit because they are moved from place to place, increasing their access to food, the whales or sea turtles are not affected by the barnacles o Parasitism A parasite lives on or in another organism- its host Ticks, fleas, leeches, lice and mites are examples of parasites that live outside the host, attached to skin or scales o Predator/prey An interaction in which one species (a predator) feeds on another species (prey) Lynx feeds on snowshoe hares Techniques of field ecology o Field ecology techniques such as sampling and quadrate studies to determine species diversity and changes over time Abiotic and biotic factors o How they relate to each other and their importance in ecosystems Abiotic factors- nonliving parts of the environment (water, soil, light, temperature, wind, and physical space) Biotic factors- living parts of the environment Sunlight, water, temperature, and wind are all abiotic factors that affect climate (climate is the typical weather pattern of an area over time) Climate plays a major role in determining the biosphere ecosystems are distributed throughout the biosphere Biome- a large group of similar ecosystems Carrying capacity o How limiting factors influence carrying capacity (eg. Food availability, harsh winter) A limiting factor is any biotic or abiotic resource in the environment that limits the size of a population Density dependent limiting factors- factors that only become limiting when the population density (the number of organisms per unit of space) reaches a certain level Density independent limiting factors- environmental factors that can disrupt or destroy all sorts of populations in the same way regardless of their density Weather, seasonal cycles, natural disasters, and many human activities Population growth graphs (J and S curves) j shaped curve- exponential growth s shaped curve- reached carrying capacity Carrying capacity The number of individuals in a population that an environment can support over a relatively long period of time 5.02 Analyze the flow of energy and the cycling of matter in the ecosystem Relationship of the carbon cycle to photosynthesis and respiration o Investigate the carbon cycle as it relates to photosynthesis and respiration During photosynthesis producers such as plants and algae take up carbon dioxide from the air or water around them. Producers use carbon dioxide and water to manufacture glucose, during which oxygen is released Producers and consumers use glucose to fuel the process of cellular respiration The reaction releases energy and produces water and carbon dioxide. The carbon dioxide produced by the reaction is released into the air or water surrounding the organism People have burned large amounts of fossil fuels (an energy rich compound formed from organic matter by a geological process) for energy, releasing huge amounts of carbon dioxide o Water cycle When water evaporates from oceans, lakes, or other bodies of water, it enters the atmosphere as a gas- water vapor In the atmosphere, the water vapor cools and condenses to form clouds Eventually, clouds release the water they contain, and the water returns to Earth’s surface as precipitation- rain, snow, hail, or sleet Water from precipitation may collect on the Earth’s surface to form streams, rivers, and lakes. Most of the water eventually flows back to the ocean, carrying nutrients and sediments with it. Some water seeps into the ground instead of running off. It slowly percolates through soil and rock layers and is being filtered and purified along the way. Eventually, water moving down through the soil reaches groundwater deep beneath the surfaces Water cycles through living things as well (transpiration, perspiration, excreation, inhalation) o Nitrogen cycle Nitrogen gas in the air is converted to usuable nitrogen compounds in a process called nitrogen fixation. Lightning causes some nitrogen fixation by forming nitrogen oxides from nitrogen and oxygen in the air. Some nitrogen fixing bacteria live in soil or water. Others live in nodules on the roots of plants that belong to the legume family (alfalfa, peanuts, soybeans, clover, peas) Nitrogen fixing bacteria convert nitrogen gas to ammonia which quickly dissolves in water to produce ammonium ions. Certain bacteria convert ammonium ions to nitrates in a two step process Plants use the nitrogen compounds they absorb to make amino acids, proteins, and other needed substances. Animals get the nitrogen they need by eating plants or the organisms that consume plants Decomposers break down nitrogen-containing animal wastes and the remains of dead organisms. The breakdown of these materials releases ammonia, which dissolves to produce ammonium ions. Plants take up ammonium ions and nitrates, and the cycle starts over again Denitrification- a group of bacteria converts some of the ammonia and nitrates into free nitrogen gas Trophic levels- direction and efficiency of energy transfer o Analyze food chains, food webs, and energy pyramids o Trophic levels- each step in the transfer of energy and matter in an ecological community o Food chains- models the flow of energy through organisms in a community o Direction of energy transfer o Efficiency of energy transfer 5.03 Assess human population and its impact on local ecosystems and global environments. Historic and potential changes in population o Factors affecting birth rates and death rates In many industrialized countries, declining death rates have a greater effect on total population growth than increasing birth rates Fertility rates are decreasing People are waiting until their thirties to have children Today’s families are having fewer children When fertility rates are high, populations grow more rapidly unless the death rate is also high Some countries have high death rates among children because of disease and malnutrition. o Effects of population size, density, and resource use on the environment Expanding human population is placing huge demands on natural resources As population has grown, humans have developed medical, agricultural, and other technologies that enable more people to survive. o Correlate “J” and “S” curves with food availability and population o How changes in population is related to other organisms Factors associated with those changes Climate Change o Discussion of factors that influence climate change Global warming Carbon and other emissions as the cause of global warming o Increased levels of carbon dioxide may lead to changes in earth’s climate. These climate changes are possible because carbon dioxide in the atmosphere traps heat as does glass in a greenhouse. If carbon dioxide levels continue to increase, global warming may occur o Global warming is an increase in earth’s average surface temperature Possible effects of global warming o Could cause the oceans to warm and expand, raising sea levels o If polar ice caps melt, sea levels could rise by many meters, flooding coastal cities and causing low lying islands to disappear o Could change rainfall patterns and increase the amount of violent weather, such as hurricanes and tornados Ways to decrease carbon production o Reducing the use of fossil fuels o Preserving forests Acid rain Habitat destruction Natural environmental processes Primary succession o Communities begin to form where none existed before o Lichens, which grow on bared rock, and other pioneer species form a pioneer community o In time, enough soil accumulates to support the growth of grasses o Over time, enough soil accumulates to support the growth of shallow rooted trees such as pines o In the shade of the pines, conditions may favor the growth of broadleaf trees such as maple and beech Secondary succession o occurs where a community has been cleared by a disturbance that did not destroy the soil Climax community o A climax community is one that has achieved relative stability and species diversity Resource use o Investigation of the direct and indirect impact of humans on natural selection on natural resources (directly-deforestation, indirectlypesticide use and bioaccumulation) Bioaccumulation (biological magnification) of some pesticides resulting in unintended effects Biological magnification- buildup of a pollutant in organisms at higher trophic levels Ex. DDT Effects of some pesticides on non-target populations Resistance to pesticides as an adaptation of some species Pros and cons of biocontrols as alternatives to pesticides Contribution of Rachel Carson Sustainable practices/stewardship o Examples of sustainable practices and stewardship