Copyright Pearson Prentice Hall 3-1 What Is Ecology? Photo Credit: ©Bruce Coleman, LTD/Natural Selection Copyright Pearson Prentice Hall

Interactions and Interdependence Ecology is the scientific study of interactions among organisms and between organisms and their environment, or surroundings. Copyright Pearson Prentice Hall

Interactions and Interdependence The biosphere contains the combined portions of the planet in which all of life exists, including: land water air, or atmosphere The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean. Copyright Pearson Prentice Hall

Interactions and Interdependence Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live. The interdependence of life on Earth contributes to an ever-changing, or dynamic, biosphere. Copyright Pearson Prentice Hall

Levels of Organization What different levels of organization do ecologists study? Copyright Pearson Prentice Hall

Levels of Organization To understand relationships within the biosphere, ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere. The levels of organization that ecologists study include: individuals, populations, communities, ecosystems, and biomes. Copyright Pearson Prentice Hall

Levels of Organization Biosphere Biome Ecosystem Community The study of ecology ranges from the study of an individual organism to populations, communities, ecosystems, biomes—and, finally, to the entire biosphere. The information that ecologists gain at each level contributes to our understanding of natural systems. Population Individual Copyright Pearson Prentice Hall

Levels of Organization A species is a group of organisms so similar to one another that they can breed and produce fertile offspring. Populations are groups of individuals that belong to the same species and live in the same area. Communities are assemblages of different populations that live together in a defined area. Copyright Pearson Prentice Hall

Levels of Organization An ecosystem is a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment. A biome is a group of ecosystems that have the same climate and similar dominant communities. The highest level of organization that ecologists study is the entire biosphere itself. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Methods What methods are used to study ecology? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Methods Ecological Methods Regardless of the tools they use, scientists conduct modern ecological research using three basic approaches: observing experimenting modeling All of these approaches rely on the application of scientific methods to guide ecological inquiry. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Methods Observing  Observing is often the first step in asking ecological questions. Some observations are simple. Others are complex and may form the first step in designing experiments and models. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Methods Experimenting Experiments can be used to test hypotheses. An ecologist may set up an artificial environment in a laboratory to imitate and manipulate conditions that organisms would encounter in the wild. Other experiments are conducted within natural ecosystems. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Methods Modeling Ecologists make models to gain insight into complex phenomena. Many ecological models consist of mathematical formulas based on data collected through observation and experimentation. The predictions made by ecological models are often tested by further observations and experiments. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-1 The combined portions of the planet in which life exists, including land, water, and the atmosphere, form the biosphere. community. species. ecosystem. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-1 A group of organisms that can breed and produce fertile offspring is known as a(an) ecosystem. species. biome. community. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-1 Compared to a community, an ecosystem includes the nonliving, physical environment as well as the community. only the physical environment of an area without the organisms. the entire biome but not the biosphere. only one of the populations within the community. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-1 An ecological method that uses mathematical formulas based on data collected is observing. experimenting. modeling. hypothesizing. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-1 An ecologist marks out an area in a specific ecosystem and proceeds to identify the number of insect species in the area. This is an example of ecological experimentation. observation. modeling. inference. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Where does the energy for life processes come from? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Producers Without a constant input of energy, living systems cannot function. Sunlight is the main energy source for life on Earth. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers In a few ecosystems, some organisms obtain energy from a source other than sunlight. Some types of organisms rely on the energy stored in inorganic chemical compounds. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food. These organisms are called autotrophs. Because they make their own food, autotrophs are called producers. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Energy From the Sun The best-known autotrophs harness solar energy through a process known as photosynthesis. During photosynthesis, these autotrophs use light energy to convert carbon dioxide and water into oxygen and energy-rich carbohydrates. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Photosynthesis is responsible for adding oxygen to—and removing carbon dioxide from—Earth's atmosphere. Sunlight is the main energy source for life on Earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Plants use the energy from sunlight to carry out the process of photosynthesis. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Life Without Light Some autotrophs can produce food in the absence of light.   When organisms use chemical energy to produce carbohydrates, the process is called chemosynthesis. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Producers Sunlight is the main energy source for life on Earth. Some types of organisms rely on the energy stored in inorganic chemical compounds. Other autotrophs, such as sulfur bacteria, use the energy stored in chemical bonds for chemosynthesis. In both cases, energy-rich carbohydrates are produced. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Consumers Consumers Many organisms cannot harness energy directly from the physical environment. Organisms that rely on other organisms for their energy and food supply are called heterotrophs. Heterotrophs are also called consumers. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Consumers There are many different types of heterotrophs. Herbivores eat plants. Carnivores eat animals. Omnivores eat both plants and animals. Detritivores feed on plant and animal remains and other dead matter. Decomposers, like bacteria and fungi, break down organic matter. Copyright Pearson Prentice Hall

Feeding Relationships How does energy flow through living systems? Copyright Pearson Prentice Hall

Feeding Relationships Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Copyright Pearson Prentice Hall

Feeding Relationships Food Chains A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Copyright Pearson Prentice Hall

Feeding Relationships In some marine food chains, the producers are microscopic algae and the top carnivore is four steps removed from the producer. Small Fish Zooplankton Squid Food chains show the one-way flow of energy in an ecosystem. In this marine food chain, energy is passed from the producers (algae) to four different groups of consumers. Shark Algae Copyright Pearson Prentice Hall

Feeding Relationships Food Webs Ecologists describe a feeding relationship in an ecosystem that forms a network of complex interactions as a food web. A food web links all the food chains in an ecosystem together. Copyright Pearson Prentice Hall

Feeding Relationships This food web shows some of the feeding relationships in a salt-marsh community. This illustration of a food web shows some of the feeding relationships in a salt marsh. Copyright Pearson Prentice Hall

Feeding Relationships Trophic Levels Each step in a food chain or food web is called a trophic level. Producers make up the first trophic level. Consumers make up the second, third, or higher trophic levels. Each consumer depends on the trophic level below it for energy. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids How efficient is the transfer of energy among organisms in an ecosystem? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids Ecological Pyramids The amount of energy or matter in an ecosystem can be represented by an ecological pyramid. An ecological pyramid is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids Ecologists recognize three different types of ecological pyramids: energy pyramids biomass pyramids pyramids of numbers Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids 0.1% Third-level consumers Energy Pyramid: Shows the relative amount of energy available at each trophic level. Only part of the energy that is stored in one trophic level is passed on to the next level. 1% Second-level consumers 10% First-level consumers Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. 100% Producers Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids Biomass Pyramid: Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid. 50 grams of human tissue 500 grams of chicken 5000 grams of grass Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Ecological Pyramids Pyramid of Numbers: Shows the relative number of individual organisms at each trophic level. Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–2 The main source of energy for life on Earth is organic chemical compounds. inorganic chemical compounds. sunlight. producers. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–2 Organisms that feed on plant and animal remains and other dead matter are detritivores. carnivores. herbivores. autotrophs. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–2 How does a food web differ from a food chain? A food web contains a single series of energy transfers. A food web links many food chains together. A food web has only one trophic level. A food web shows how energy passes from producer to consumer. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–2 In a biomass pyramid, the base of the pyramid represents the mass of heterotrophs. primary consumers. producers. top level carnivores. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–2 The amount of energy represented in each trophic level of consumers in an energy pyramid is about 10% of the level below it. 90% of the level below it. 10% more than the level below it. 90% more than the level below it. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3-3 Cycles of Matter How does matter move among the living and nonliving parts of an ecosystem? Copyright Pearson Prentice Hall

Recycling in the Biosphere Energy and matter move through the biosphere very differently. Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Biogeochemical Cycles Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Water Cycle The Water Cycle All living things require water to survive. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Water Cycle Water moves between the ocean, atmosphere, and land. This diagram shows the main processes involved in the water cycle. Scientists estimate that it can take a single water molecule as long as 4000 years to complete one cycle. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles How are nutrients important in living systems? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles Nutrient Cycles All the chemical substances that an organism needs to sustain life are its nutrients. Every living organism needs nutrients to build tissues and carry out essential life functions. Similar to water, nutrients are passed between organisms and the environment through biogeochemical cycles. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles The Carbon Cycle Carbon is a key ingredient of living tissue. Biological processes, such as photosynthesis, respiration, and decomposition, take up and release carbon and oxygen. Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles CO2 in Atmosphere Photosynthesis Volcanic activity feeding Respiration Erosion Human activity Respiration Decomposition CO2 in Ocean Uplift Carbon is found in several large reservoirs in the biosphere. In the atmosphere, it is found as carbon dioxide gas; in the oceans as dissolved carbon dioxide; on land in organisms, rocks, and soil; and underground as coal, petroleum, and calcium carbonate rock.  Deposition Photosynthesis feeding Fossil fuel Deposition Carbonate Rocks Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles The Nitrogen Cycle All organisms require nitrogen to make proteins. Although nitrogen gas is the most abundant form of nitrogen on Earth, only certain types of bacteria can use this form directly. Such bacteria live in the soil and on the roots of plants called legumes. They convert nitrogen gas into ammonia in a process known as nitrogen fixation. Copyright Pearson Prentice Hall

NH3 N2 in Atmosphere NO3 and NO2 Nutrient Cycles Synthetic fertilizer manufacturer Atmospheric nitrogen fixation Decomposition Uptake by producers Reuse by consumers Uptake by producers Reuse by consumers The atmosphere is the main reservoir of nitrogen in the biosphere. Nitrogen also cycles through the soil and through the tissues of living organisms.  Decomposition excretion Decomposition excretion Bacterial nitrogen fixation NO3 and NO2 NH3 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles Other soil bacteria convert nitrates into nitrogen gas in a process called denitrification. This process releases nitrogen into the atmosphere once again. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles The Phosphorus Cycle Phosphorus is essential to organisms because it helps forms important molecules like DNA and RNA. Most phosphorus exists in the form of inorganic phosphate. Inorganic phosphate is released into the soil and water as sediments wear down. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Cycles Organic phosphate moves through the food web and to the rest of the ecosystem. Organisms Phosphorus in the biosphere cycles among the land, ocean sediments, and living organisms. Land Ocean Sediments Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Limitation Nutrient Limitation The primary productivity of an ecosystem is the rate at which organic matter is created by producers. One factor that controls the primary productivity of an ecosystem is the amount of available nutrients. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Limitation If a nutrient is in short supply, it will limit an organism's growth. When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly, this substance is called a limiting nutrient. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Nutrient Limitation When an aquatic ecosystem receives a large input of a limiting nutrient—such as runoff from heavily fertilized fields—the result is often an immediate increase in the amount of algae and other producers. This result is called an algal bloom. Algal blooms can disrupt the equilibrium of an ecosystem. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–3 Transpiration is part of the water cycle. carbon cycle. nitrogen cycle. phosphorus cycle. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–3 Carbon is found in the atmosphere in the form of carbohydrates. carbon dioxide. calcium carbonate. ammonia. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–3 Biologists describe nutrients as moving through cycles because the substances start as simple organic forms that plants need. provide “building blocks” and energy that organisms need. are passed between organisms and the environment and then back to organisms. are needed by organisms to carry out life processes. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–3 The only organisms that can convert nitrogen in the atmosphere into a form useful to living things are nitrogen-fixing plants. bacteria. detritivores. animals. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 3–3 When an aquatic ecosystem receives a large input of a limiting nutrient, the result is runoff. algal death. algal bloom. less primary productivity. Copyright Pearson Prentice Hall