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Levels of Ecological Organization Organism: A living thing-smallest level Population: all the individuals of the same species (ducks) Community: all the different species in an area (ducks + maple trees + dragonflies) Ecosystem: the community plus the physical factors in an area (ducks + maple trees + dragonflies + temperature + soil + rainfall) Biosphere: thin zone of life around the planet-all the earth’s ecosystems-largest ecological level Factors Affecting Ecosystems Biotic Factors: living elements in an ecosystem (plants & animals) Abiotic Factors: non living elements in an ecosystem (soil, sunlight, temp, water, noise, air, water, rocks, minerals, climate) Habitat: the physical space where an organism lives (its home) BIODIVERSITY: a measure of the number of different species in an ecosystem. Some ecosystems are more diverse than others. Succession: process where organisms arrive and inhabit a new ecosystem: Pioneer species: the first to inhabit a new area Climax community-final community-ends succession *See text on page 463-464. Primary Succession: formation of an ecosystem from scratch Secondary Succession: new ecosystem develops after an existing one is disturbed Practice quiz: http://www.ekcsk12.org/science/regbio/ecologyqz2.html 1 Energy Flow in Ecosystems Productivity: the total amount of photosynthesis carried out by producers in an ecosystem. Producers: autotrophs-(self-feeders)capture energy from the sun, convert to organic material -- plants (make their own food) Consumers: Heterotrophs (other feeders)organisms that gain their energy from eating other things – animals herbivores-eat only plants carnivores--eat only animals omnivores-eat both plants & animals decomposers-consume dead organisms-most common are bacteria & fungi Food Chain Pathway in which energy flows from organism to organism A food chain is a series of organisms each feeding on the one preceding it. There are two types of food chains: Decomposer - chains are composed of waste and decomposing organisms such as fungi and bacteria. Grazer - food chains begin with algae and plants and end with a carnivore. primary producer primary consumer secondary consumer tertiary consumer decomposer 2 Food Web Complex array of interconnected food chains Herbivores Carnivores Omnivores Producers Primary Consumers Secondary Consumers Tertiary Consumers Decomposers - cause decay Detritivore - an organism that feeds on dead or waste (bacteria, fungi) Saprophyte-plant decomposers, such as mushrooms 3 How Ecosystems Work The Flow of Energy Ecosystem Function 1. Energy moves thought ecosystems in a one-way flow. It must constantly be replenished. 2. Nutrients cycle and recycle in a continuous flow Autotrophs: "self feeders", producers, plants Heterotrophs: "other feeders", consumers, animals The amount of life an ecosystem can support is determined by the energy captured by the producers Net primary productivity -- measured in calories or biomass -The more sunlight & water, the more plants, the more animals etc Trophic level - the level at which an organism feeds Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (carnivores that eat other carnivores) Quaternary consumers (eat tertiary consumers) 4 Organisms can move from one trophic level to another, by eating different types of things. Food Chains and Food Webs illustrate feeding relationships in ecoysystems Detritus feeders: decomposers, feed on refuse and return nutrients to the cycle 5 Energy Pyramids - illustrate how energy is transferred between trophic levels. Energy Transfer - as you go up trophic levels, organisms lose energy. An ecosystem can support more primary consumers, than tertiary consumers Biological Magnification - toxins build up to higher levels as you move up in the food chain. (Example: DDT) Biogeochemical Cycles (Nutrient Cycles) Ecosystems Cycle Material water cycle carbon cycle nitrogen cycle phosphorus cycle 6 Water Cycle ground water- transpiration (from plants)- evaporation (from bodies of water) condensation- precipitation (from clouds)- 7 Carbon Cycle Respiration (breathing of animals) Combustion (burning) Photosynthesis (uses CO2 and converts to oxygen) 8 Nitrogen Cycle Nitrogen is a fertilizer for plants 79% of the air is made of nitrogen Legumes- 9 Phosphorus Cycle Phosphorus is found in ATP-adenosine triphosphate-an important molecule found in cellsconverted to get energy 10 Community Interactions Community: All the interacting populations in an ecosystem Competition Predation Symbiosis Symbiosis: means "living together" --, a close interaction between organisms of different species. Parasitism: one is harmed (host), one benefits (ticks and deer) Commensalism: one benefits, the other is unaffected (birds and trees) Mutualism: both species benefit (termites & protozoa) The Ecological Niche - A species way of life, each species in an ecosystem occupies its own niche-its job Fundamental niche - the set of resources a population is theoretically capable of using under ideal circumstances Realized niche - the set of resources the population actually uses (due to competition and resource partitioning) Compare the following fish eating birds that live near a lake Heron- wades in water, spears fish on the shoreline Kingfisher - perches and nests in trees, hunts by swooping and spearing prey Loon - a duck-like bird that paddles and dives to catch fish Each bird lives in the same ecosystem, eats the same food, but occupies a different NICHE Competitive Exclusion Principle - no two species can occupy the same niche. If two species with the same niches are places together, they will be forced to compete, one will survive. Resource Partitioning - species with similar requirements coexist but occupy smaller niches than they would if they lived alone. Other examples of interspecific competition and resource partitioning 5 species of warblers hunt for food in different areas of a tree 2 species of barnacles occupy deeper and shallower areas of a shoreline Predators and Prey Coevolution drives adaptations. Prey become better at evading, Predators better at catching Some prey adaptations Camouflage - coloration allows organisms to blend Warning coloration - bright colors advertise danger Startle Coloration - eyespots on caterpillers 11 Mimicry Aggressive Mimicry - enhances predation Mullerian mimicry - all dangerous species resemble each other (bright colors) Batesian mimicry - harmless species resemble dangerous ones 12 Biomes of the Earth Climate is the primary factor that determines what organisms can live in any given habitat. Therefore, climate is wha causes certain areas of the earth to become distinctive A BIOME is a major ecosystem spread over a wide geographic area, and characterized by certain types of flora and fauna. (plants and animals) Note the relative locations of the biomes, anything between the two tropics is considered to be "Tropical", areas above those lines are called "Temperate" and then even farther north (or south) you have polar. It is important to remember those words because there are both temperate and tropical forests - each having different attributes determined primarily by the climate of the area. Classification of biomes is by PRODUCTIVITY - how much biomass is gained over a period 13 Aquatic Biomes Marine - oceans Freshwater - lakes, ponds, rivers, streams Varies in temperature, depending on location Some lakes freeze over (Winterkill) Saltwater Photic zone - receives light Aphotic zone - not enough light for photosynthesis 14 Terrestrial Biomes Polar Very little plant growth (if any) Photosynthetic organisms are marine Bitterly cold temperatures Supports some marine mammals & birds (penguins, whales) Chaparral Temperate Grassland - Prairie Few trees, good soil supports grasses Used as farmland Animals: deer, buffalo Found in dry regions of the mediterranian Also called "scrubland" Plants are mainly spiny shrubs Animals: lizards, rodents, coyotes, birds 15 Taiga - Coniferous Forest Found in Northern areas and on mountain sides Conifers have needles shaped to shrug off snow (evergreens) Logging of treese has reduced some forests Animals: deer, wolf, foxes, birds Desert Temperate Deciduous Forest Very hot in day, cold at night Low amounts of rainfall Plant species are cactus or plants that store water Animals: many lizards, some birds and small mammals Usually located east of mountains Trees lose their leaves in the fall Animals: fox, coyote, squirrels, rabbits, deer Plants(trees): Oak, Maple, Sweet Gum 16 Tundra Rainforest Savanna Very dry, followed by short periods of heavy rain Plants - grasses and drought resistant trees Animals: elephants, gazelle, zebra, giraffe Can be tropical (near equator) or temperate High levels of rain Great diversity of plants and animals In mature forests, the floor doesn't have much growth due to tree canopy blocking out the light Cold and Dry Permafrost - layer of soil that remains permanently frozen Large trees cannot grow, but grasses can in the warmer season Supports migratory animals: caribou, wolves, bear Lichens - major photosynthetic food source 17 Population Growth and Regulation How Populations Grow Factors the determine how much a population will change 1. births 2. deaths 3. migration Stable populations occur when as many individuals join (birth or immigration) as leave (death or emigration) Population change = (birth - deaths) + (immigrants - emigrants) Factors that influence biotic potential: 1. 2. 3. 4. 5. age of reproduction frequency of reproduction number of offspring produced reproductive life span average death rate under ideal conditions Environmental Resistance: Decreases the birth rate, or increases death rate, related to environmental conditions, such as food & space. Density Independent Factors: weather and other natural disasters Density Dependent Factors: food, space, water, parasitism, competition Growth rate (r) = birth rate (b) - death rate (d) Population growth = rN (r = growth rate, N = original population size) 18 J-shaped curve showing exponential growth of a population S-shaped curve shows how a population This population has not yet reached its carrying capacity. Carrying Capacity: the maximum size of becomes limitied by environmental factors a population that an area can support Boom and Bust Cycles Rapid population growth followed by a massive die-off Populations that are influenced by seasonal weather patterns, such as cold and drought Predator-Prey Cycles Most populations fluctuate in cycles. The prey population rises, causing the predator population to also ris then overfeed on prey, causing the prey population to drop, Once the prey population drops, the predato drops due to lack of food. The cycle repeats indefinitely. 19 Competition Resources limit the size of populations as individuals compete Interspecific competition: occurs between members of different species Intraspecific competition: occurs beweeen members of the same species Scramble competition: free-for-all, plants disperse seeds and as they grow they choke out other seedlings Contest competition: social interaction in animals that leads to the gaining of resources Contest competition: social behaviors, territoriality Dominance heirarchies: pecking orders within members of a species, dominant individuals get more resou priveleges Population Patterns in Space and Tim Distributions Clumped Random Uniform 20 Survivorship curve Early loss Constant loss Late Loss 21 Human Impact On the Earth Pollution DDT (dichloro diphenyl trichloro ethane) Starting in the 1940's, the chlorinated hydrocarbon DDT was used in vast quantities all over the world for killing insects. It was cheaper and much more effective than other insecticides against nearly all insects. It saved millions of lives by killing the mosquitoes that spread malaria and saved millions from starvation by killing crop pests.. But: in the 1950's and 1960's there was an alarming decline in the populations of several predatory birds, particularly fish-eaters such as bald eagles, cormorants, ospreys and brown pelicans. DDT is toxic at high levels; but at lower levels it interferes with calcium deposition in eggshells, causing them to be thin, fragile, and often crushed by the parents in the nest. Although DDT was suspected, the levels to which the birds had been exposed were nowhere near high enough to have killed them. But when the bird's bodies were analyzed, they were found to have up to one million times the concentration that was present in the sprayed water. This led to the discovery of bioaccumulation (also known as biological magnification), which means the steady increase in concentration of a contaminant with increasing level in the food chain. In the case of DDT, it results from the following factors: 1. DDT is not metabolized, and does not break down in the body. 2. It is much more soluble in fat than in water. So it accumulates in body fat and is not excreted. 3. The transfer of energy from lower trophic levels to higher ones is inefficient -so herbivores eat large quantities of plant material, and carnivores eat many times their body weight of prey during their lifetime. Since DDT is not excreted, the carnivore accumulates most of the DDT that was present in all of the prey organisms. AIR POLLUTION AND ACID RAIN Each year the U.S. discharges into the atmosphere: 15 million tons sulfur dioxide: 70% from power plants burning coal or oil. 30% from smelters and refineries. 20 million tons nitrogen oxides: 40% from cars, trucks, planes 30% from power plants 30% from other industrial sources. 22 Sulfur dioxide and nitrogen oxides combine with water in the air to form sulfuric acid and nitric acid, causing acid rain, Acid rain destroys plants and animals in several different ways: 1. Acidification of lakes directly kills algae, invertebrates, amphibians, and ultimately fish. The result is a crystal clear lake that is beautiful but dead 2. Removal of soil nutrients. Acid rain dissolves essential nutrients, including calcium and potassium, out of the soil thus reducing their availability to plants. It also kills microorganisms, preventing decomposition from returning nutrients to the soil. 3. Dissolving toxic metals. Acid rain also dissolves toxic metals, such as aluminum and mercury, which are otherwise insoluble and harmless. CLIMATE CHANGE The earth's climate may be warming as a result of the accumulation of "greenhouse gases", notably carbon dioxide. The kinds of data supporting this conclusion are. Record breaking daily temperatures Heat waves Rise in sea level Retreat of glaciers Icebergs breaking of Antarctica Early thaws Increased rain and snow falls *Many scientists feel that this is not enough data (over too small of a time period) to judge LOSS OF BIODIVERSITY (Extinctions) Habitat Loss ** Pollution Overexploitation International Trade (Poaching) Disease Introduction of Exotic Species THE U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA) EPA's purpose is to ensure that: All Americans are protected from significant risks to human health and the environment where they live, learn and work. National efforts to reduce environmental risk are based on the best available scientific information. Federal laws protecting human health and the environment are enforced fairly and effectively. All parts of society-communities, individuals, business, state and local governments, tribal governments-have access to accurate information 23 sufficient to effectively participate in managing human health and environmental risks. Environmental protection contributes to making our communities and ecosystems diverse, sustainable and economically productive. The United States plays a leadership role in working with other nations to protect the global environment. **Some people feel the EPA is not doing what it was intended to do. That, the EPA often finds itself in conflict with landowners, towns, and individuals --> Remeber the Stossel Report on the Lead in Aspen? The EPA's Pesticide Program Over 20,000 pesticide products have been registered for use in the United States. EPA is responsible for regulating the sale and use of pesticides, and the allowable levels in or on food. EPA is responsible for registering, or licensing pesticide products - based on assessment of the potential effects on human health and the environment, when used according to label directions. EPA's Strategy for Persistent, Bioaccumulative and Toxic pollutants (PBT) : When a company or individual introduces a new chemical or a significant new use of a chemical, they must obtain a permit from the EPA. Tests include: biodegradability in a single-organism test biodegradability in a laboratory microcosm bioaccumulation potential chronic toxicity to fish (rainbow trout) and daphnids CITES International trade puts enormous economic pressure on suppliers and threatens the existence of many rare plants and animals. For this reason in 1975 the U.S., along with nine other countries, signed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). The objective of CITES, which now involves over 150 countries, is to ensure that trade will not cause the extinction of plant or animal species. CITES maintains lists of threatened species and regulates the import and export of those species. Examples of animals on CITES lists: Great apes, Great whales, African elephant, All rhinoceros species, Giant Panda, sea turtles, crocodilians, Large cats, Several orchids, cacti and cycads The U.S. Endangered Species Act of 1973 (ESA) Unlike previous legislation, the act was not designed to protect only those species that were economically useful or potentially useful to man; it is based on the idea that species are of "aesthetic, ecological, educational, historical, recreational and scientific value to the nation and its people". The ultimate purpose of the Endangered Species Act is to bring about the recovery of endangered and 24 threatened species. The Supreme Court has interpreted the act to mean that the value of species cannot be calculated, and that listed species should be protected whatever the cost. The ESA requires the following: It requires the Secretary of the Interior (through the U.S. Fish and Wildlife Service or, for marine species, the National Marine Fisheries Service) to identify and publish lists of species that are endangered (in imminent danger of going extinct) or threatened (likely to become endangered in the foreseeable future). A decision whether to list must be based solely on the biological evidence; economic factors are not relevant at this stage. Anybody that can provide adequate evidence can make a proposal for listing. Endangered species are given full legal protection against exploitation: they cannot be "taken ". "Take" means harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in such conduct. Such activities directed against animals are illegal even on private land. The federal government is prohibited from engaging in activities that could jeopardize the continued existence of listed species or adversely affect their designated critical habitat. A recovery plan must be developed and the recovery of the species must be monitored. The species or its products cannot be exported or imported. Criticisms of the ESA 1. It doesn't help endangered species 2. It makes enemies of landowners 3. Species listing becomes political 4. It interferes with human (and homeowners) rights 5. It damages the economy Animal Welfare Act Requires that animals have: proper and sufficient food and water adequate shelter the opportunity to display normal patterns of behavior physical handling in a way which minimizes the likelihood of unreasonable or unnecessary pain or distress protection from, and rapid diagnosis of, any significant injury or disease. Act covers: pet stores, research, hunting, pets, zoos, circuses Clean Air Act The 1990 Clean Air Act is a federal law covering the entire country; states do much of the enforcement. For example, a state air pollution agency holds a hearing on a permit application by a power or chemical plant or fines a company for violating air pollution limits. Under this law, EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country. 25 Environmental Issues Human Overpopulation " How to share and renew resources " Energy Conservation " Managing waste " Managing populations " Loss of fertile lands (desertification, topsoil loss) Loss of Biodiversity (Extinctions) " Deforestation " Urban Sprawl " Endangered Species Act " Illegal Animal Trade " Exotic (Invasive) Species " Overfishing Global Warming " Greenhouse Gases " Is global warming happening? " How will it affect life on the planet? Air Pollution / Water Pollution " Acid Rain " Clean Air Act " Nitrification of Lakes (Runoff) " Sources of Clean Water " Ozone hole (Chloroflourocarbons) " Toxins in the environment (DDT) & biological magnification 26