CH-3-4 Ecosystems: What Are They and How Do They Work – Living in the Environment: Principles, Connections, and Solutions : Book Guide

This Document Contains Chapters 3 to 4 Chapter 3 Ecosystems: What Are They and How Do They Work Summary 1. Ecology is the study of connections in nature. 2. Life on earth is sustained by the one-way flow of high-quality energy from the sun, by the cycling of matter, and by gravity. 3. Matter, energy, and life are the major components of an ecosystem. 4. Energy in an ecosystem decreases in amount to each succeeding organism in a food chair or web. 5. Soil is a complex mixture of eroded rock, mineral nutrients, water, air, decaying organic matter, and billions of living organisms. It covers most of the earth and provides nutrients for plant growth. Soils are formed by a breaking down of rock, decomposing surface litter and organic matter. Bacteria and other decomposer microorganisms break down some of soil’s organic compounds into simpler inorganic compounds. 6. Matter is recycled through the earth’s ecosystem of air, land, water, and living organisms. This vast global recycling system is composed of nutrient cycles. 7. Scientists study ecosystems through the use of aquarium tanks, greenhouses, and controlled indoor and outdoor chambers. Specific variables are carefully controlled, like temperature, light, carbon dioxide, and humidity. 8. Two principles of sustainability found from learning how nature works are the law of conservation of matter and the two laws of thermodynamics. Outline 3-1 What keeps us and other organisms alive? CORE CASE STUDY. Tropical rainforests make up only 2% of the earth’s land surface, but account for more than half of all biodiversity. Already more than half of this area has been destroyed, and degradation is increasing. This will cause a reduction in biodiversity, an increase in climate change, and changes in regional weather patterns. A. Earth’s life support system consists of four main systems: atmosphere (air), hydrosphere (water), geosphere (earth) and the biosphere (living things). 1. Atmosphere contains many layers: a. The troposphere extends 17 km up and contains the air we breathe. About 1% is composed of greenhouse gases (water vapor, methane and carbon dioxide), which absorb energy to warm the lower atmosphere. b. The stratosphere lies 17–50 km above the troposphere and filters the sun’s harmful radiation. c. The hydrosphere consists of earth’s water, found in liquid water, ice, and water vapor. d. The geosphere consists of the earth’s core, mantle, and crust. e. The biosphere is where life is found. B. Life on earth depends on three interconnected factors 1. The one-way flow of high-quality solar energy. 2. The cycling of nutrients. 3. Gravity. C. Solar energy reaches earth as electromagnetic waves in the form of visible light, UV radiation and heat. D. As solar radiation interacts with the earth, infrared radiation is produced. Greenhouse gases trap the heat and warm the troposphere. This natural greenhouse effect makes the planet warm enough to support life. 1. Human activities add greenhouse gasses to the atmosphere, intensifying the greenhouse effect. 3-2 What are the major components of an ecosystem? A. Ecology is the study of connections in the natural world. 1. There are five levels of study: organisms, populations, communities, ecosystems and the biosphere. 2. Ecosystems are comprised of living (biotic) and non-living (abiotic) components. 3. Every organism occupies a trophic (feeding) level. a. Producers, or autotrophs, make their own food from compounds in the environment. Photosynthesis is the process by which plants take solar energy, carbon dioxide and water to form energy rich sugars. Chemosynthesis is the process by which some organisms can use geothermal energy to produce complex nutrient compounds. 4. Consumers, or heterotrophs, feed on other organisms. a. Herbivores (primary consumers) feed on plants. b. Carnivores feed on animals. c. Secondary consumer feed on herbivores d. Tertiary consumers feed on other carnivores. e. Omnivores feed on both plants and animals. f. Decomposers break down organic detritus (bacteria/fungi) into simpler inorganic compounds. g. Detritivores feed on dead organic matter and break it down into smaller molecules. 5. Glucose and other organic compounds are broken down and energy is released by the process of aerobic respiration, the use of oxygen to convert organic matter back to carbon dioxide and water. 6. Some decomposers are able to break down organic compounds without using oxygen. This process is called anaerobic respiration, or fermentation. SCIENCE FOCUS: Microbes are pivotally important in terms of cycling matter, providing oxygen and regulating the earth’s temperature by removing carbon dioxide. 3-3 What happens to energy in an ecosystem? A. Food chains and food webs help us understand how eaters, the eaten, and the decomposed are interconnected in an ecosystem. B. Energy flow in a food web/chain decreases at each succeeding organism in a chain or web. C. The dry weight of all organic matter within the organisms of a food chain/web is called biomass. D. The greater number of trophic levels in a food chain, the greater loss of usable energy. F. The pyramid of energy flow visualizes the loss of usable energy through a food chain. The lower levels of the trophic pyramid support more organisms. G. Production of biomass takes place at different rates among different ecosystems. 1. The rate of an ecosystem’s biomass production is the gross primary productivity (GPP). 2. Some of the biomass must be used for the producers’ own respiration. Net primary productivity (NPP) measures how fast producers can provide biomass needed by consumers in an ecosystem. 3. Ecosystems and life zones differ in their NPP. H. The planet’s NPP limits the numbers of consumers who can survive on earth. 3-4 What happens to matter in an ecosystem? A. Nutrient cycles/biogeochemical cycles are global recycling systems that interconnect all organisms. 1. These cycles include the carbon, oxygen, nitrogen, phosphorus, and water cycles. B. The water/hydrologic cycle collects, purifies, and distributes the earth’s water in a vast global cycle. 1. Solar energy evaporates water, and the water returns as rain/snow. 2. Some water becomes surface runoff, returning to streams/rivers. 3. Water is the major form of transporting nutrients within and between ecosystems. 4. Many natural process purify water C. The water cycle is altered by man’s activities. 1. We withdraw large quantities of fresh water. 2. We clear vegetation and increase runoff, reduce filtering and increase flooding. 3. We increase flooding as we drain and alter wetlands. D. The carbon cycle circulates through the biosphere. 1. CO2 gas is an important temperature regulator on earth. 2. Photosynthesis and aerobic respiration circulates carbon in the biosphere. 3. Fossil fuels contain carbon. 4. Excess carbon dioxide in the atmosphere has contributed to global warming. E. Nitrogen is recycled through the earth’s systems by different types of bacteria. 1. The nitrogen cycle converts nitrogen (N2) into compounds that are useful nutrients for plants and animals. 2. The nitrogen cycle includes these steps: a. Specialized bacteria convert gaseous nitrogen to ammonia in nitrogen fixation. b. Special bacteria convert ammonia in the soil to nitrite ions and nitrate ions; the latter is used by plants as a nutrient. This process is nitrification. c. Decomposer bacteria convert detritus into ammonia and water-soluble salts in ammonification. d. In denitrification, nitrogen leaves the soil. Anaerobic bacteria in soggy soil and bottom sediments of water areas convert NH3 and NH4+ back into nitrite and nitrate ions, and then nitrogen gas and nitrous oxide gas are released into the atmosphere. 3. Human activities affect the nitrogen cycle. a. In burning fuel, we add nitric oxide into the atmosphere; it can be converted to NO2 gas and nitric acid, and it can return to the earth’s surface as acid rain. b. Nitrous oxide that comes from livestock, wastes, and inorganic fertilizers we use on the soil can warm the atmosphere and deplete the ozone layer. c. We destroy forest, grasslands, and wetland and, thus, release large amounts of nitrogen into the atmosphere. d. We pollute aquatic ecosystems with agricultural runoff and human sewage. e. We remove nitrogen from topsoil with our harvesting, irrigating, and land-clearing practices. F. The phosphorus cycle does not include the atmosphere. The major reservoir is terrestrial rock formations. 1. Most soils contain little phosphate, and it is often the limiting factor for plant growth. 2. Phosphorus is used as a fertilizer to encourage plant growth. 3. Phosphorus also limits growth of producers in freshwater streams and lakes due to low solubility in water. G. Humans interfere with the phosphorous cycle in harmful ways. 1. We mine phosphate rock to produce fertilizers and detergents. 2. We cut down tropical forests and, thereby, reduce the phosphorus in tropical soils. 3. Eroding topsoil moves large quantities of topsoil to aquatic systems, where it stimulates growth in algae. H. Sulfur cycles through the biosphere and much of it is stored underground in rocks and minerals. 1. Natural sources of sulfur are hydrogen sulfide, released from volcanoes, swamps, bogs, and tidal flats where anaerobic decomposition occurs. 2. Particles of sulfate, such as ammonium sulfate, enter the atmosphere from sea spray, dust storms and forest fires. 2. Some marine algae produce dimethyl sulfide (DMS). DMS acts as nuclei for condensation of water found in clouds. This can affect the cloud cover and climate. 3. Sulfur compounds can be converted to sulfuric acid, which falls as acid deposition. 4. Burning coal and oil, refining oil, and the production of some metals from ores all add sulfur to the environment. 3-5 How do scientists study ecosystems? A. Ecologists do field research, observing and measuring the ecosystem structure and function. B. New technologies such as remote sensing and geographic information systems (GISs) gather data that is fed into computers for analysis and manipulation of data. C. Ecologists use tanks, greenhouses, and controlled indoor and outdoor chambers to study ecosystems (laboratory research). This allows control of light, temperature, CO2, humidity, and other variables. D. Field and laboratory studies must be coupled together for a more complete picture of an ecosystem. E. Systems analysis develops mathematical and other models that simulate ecosystems that are large and very complex and can’t be adequately studied with field and laboratory research. This allows the analysis of the effectiveness of various alternate solutions to environmental problems and can help anticipate environmental surprises. SCIENCE FOCUS: The use of satellites as remote sensing devises and tools such as Google Earth provide for a powerful new approach to understanding the environment and conducting research. Teaching Tips Large Lecture Courses: Draw a diagram of a trophic pyramid on the board. Let the students suggest where the producers and consumers go on this diagram. Through Socratic questioning, direct them to the conclusion that consumer populations are limited by the amount of energy at the top of this pyramid. Then make the connection with food production and diet, allowing them to draw the conclusion that the best way to feed a growing human population is via a vegetarian diet. Smaller Lecture Courses: Use the example of tropical rainforest deforestation to illustrate the impacts that alterations of an ecosystem can have on the carbon and hydrologic cycles. Break the class into groups to discuss the effects of alternate land uses, such as agriculture and grazing. Then reconvene the class for a brainstorming session on the blackboard. Focus on issues that have a truly global impact, such as carbon sinks and weather patterns, in addition to erosion and loss of biodiversity. Key Terms abiotic aerobic respiration anaerobic respiration atmosphere autotrophs biogeochemical cycles biomass biosphere biotic carbon cycle carnivores chemosynthesis community consumers decomposers detritivores ecology ecosystem fermentation food chain food web greenhouse gases gross primary productivity (GPP) herbivores heterotrophs hydrologic (water) cycles hydrosphere natural greenhouse effect net primary productivity (NPP) nitrogen cycle nutrient (biogeochemical) cycles omnivores organisms photosynthesis phosphorus cycle population primary consumers producers pyramid of energy flow secondary consumers stratosphere sulfur cycle tertiary consumers trophic level troposphere Term Paper Research Topics 1. Sustaining ecosystems: the big picture. 2. Abiotic factors and range of tolerance: a comparison of terrestrial and aquatic limiting factors. 3. Biotic factors: a comparison of chemo synthesizers and photosynthesizers; lifestyles of detritivores. 4. Pyramid of energy and ecological efficiency: a comparison of ecological efficiency in different biomes. 5. Soil: the web of life in the soil, soil formation, and pioneer ecological succession; soils of your locale. 6. Cycles of matter: particular cycles of matter, clarifying chemical changes throughout the cycle; the processes of photosynthesis and respiration and how they connect autotrophic and heterotrophic organisms. 7. Energy flow: energy flow in a particular ecosystem; relationships among species in a particular ecosystem; comparison of the life of a specialist with that of a generalist. 8. Humans trying to work with ecosystems: composting; organic gardening; land reclamation; rebuilding degraded lands; tree-planting projects. 9. Methods used in ecological research: measuring net primary productivity and respiration rates; analyzing for particular chemicals in the air, water, and soil; computer modeling of ecological interrelationships. 10. Find groups focused on sustaining ecosystems and creating sustainable cities and societies in your area. Do their mission statements include the principles discussed in this chapter? Are other planks included as well? Discussion Topics 1. Should we eat lower on the food chain? Answer: Eating lower on the food chain, such as consuming more plant-based foods, can reduce the environmental impact by requiring fewer resources like water and land. It also leads to lower greenhouse gas emissions compared to meat production. However, dietary preferences and nutritional needs must be considered, as not all individuals may find plant-based diets adequate for their health. 2. Should we rely more on renewable sources of energy? Answer: Yes, relying more on renewable energy sources like solar, wind, and hydroelectric power can reduce our carbon footprint and mitigate climate change. Renewables provide a sustainable and cleaner alternative to fossil fuels, helping to decrease air pollution and dependence on finite resources. However, challenges include the intermittent nature of some renewables and the need for substantial infrastructure investments. 3. How do we affect organisms at different levels of a pyramid of energy? Answer: Humans affect organisms at different levels of the energy pyramid through activities like hunting, habitat destruction, and pollution. These actions can disrupt food chains, leading to population declines or increases in certain species, and can reduce biodiversity. Additionally, overexploitation of top predators can cause trophic cascades that alter entire ecosystems. 4. What are the advantages and disadvantages of different methods of studying ecosystems? Answer: Observational studies provide a real-world understanding of ecosystems but may be limited by observational biases and lack of control. Experimental studies allow for manipulation and control, helping to establish cause-effect relationships but may not fully capture the complexity of natural systems. Remote sensing offers large-scale data but can lack detailed, ground-level information. 5. What sustains ecosystems? What services do ecosystems provide for humans? What can humans do to help sustain ecosystems? Answer: Ecosystems are sustained by energy flow, nutrient cycling, and biodiversity. They provide services like clean air and water, pollination, soil fertility, and climate regulation. Humans can sustain ecosystems by reducing pollution, protecting natural habitats, promoting sustainable resource use, and supporting conservation efforts. 6. To what extent should we disrupt and simplify natural ecosystems for our food, clothing, shelter, and energy needs and wants? Answer: Disrupting and simplifying natural ecosystems should be minimized to maintain biodiversity and ecological balance. Sustainable practices, such as agroforestry, renewable energy, and eco-friendly materials, can help meet human needs without causing extensive harm. Balancing development with conservation is essential to ensure long-term ecological and human well-being. 7. What do nature's cycles of matter suggest about landfills, incinerators, reducing consumption, and recycling? Answer: Nature's cycles of matter emphasize the importance of recycling and reusing materials to minimize waste. Landfills and incinerators disrupt these cycles by removing materials from natural processes, contributing to pollution and resource depletion. Reducing consumption and enhancing recycling efforts align with natural cycles and promote a sustainable, circular economy. 8. Based on your current understanding of ecology, evaluate the emphasis of the United States on fossil fuels and nuclear power for energy production. Answer: The U.S. reliance on fossil fuels contributes to greenhouse gas emissions, air pollution, and climate change. While nuclear power offers a low-carbon alternative, it poses challenges like radioactive waste disposal and potential accidents. A shift toward renewable energy sources is crucial for reducing environmental impacts and promoting energy security. Investments in renewables and energy efficiency can foster a more sustainable and resilient energy system. Activities and Projects 1. Organize a class trip to a natural area such as a forest, grassland, or estuary to observe the elements of ecosystem structure and function. Arrange for an ecologist or a naturalist to provide interpretive services. 2. Bring a self-sustaining terrarium or aquarium to class and explain the structure and function of this conceptually tidy ecosystem. Discuss the various things that can upset the balance of the ecosystem and describe what would happen if light, food, oxygen, or space were manipulated experimentally. 3. Find works of literature, art, and music that show human attachment to and destruction of natural ecosystems. 4. As a class exercise, have each student list the kinds and amounts of food he or she has consumed in the past 24 hours. Aggregate the results and compare them on a per capita basis with similar statistics derived from studies of dietary composition and adequacy in food-deficient nations. How many people with a vegetarian diet could subsist on the equivalent food value of the meat consumed by your class? 5. Have the students debate the argument that eating lower on the food chain is socially and ecologically more responsible, cheaper, and healthier. (It is helpful to do this around a time when fasting is common.) Also, look at the long-term picture: will eating low on the food chain sustain an exponentially growing human population indefinitely? 6. Define an ecosystem to study on campus. As a class project, analyze the abiotic and biotic components of the ecosystem. Draw webs and construct pyramids to show the relationships among species in the ecosystem. Project what might happen if pesticides were used in the ecosystem, if parts of the ecosystem were cleared for development, or if a coal-burning power plant were located upwind. Attitudes and Values 1. Do you feel you are part of an ecosystem? What niche do you fill? Answer: Yes, humans are integral parts of ecosystems, filling multiple niches. As omnivores, humans consume a variety of foods from different trophic levels. We also act as ecosystem engineers, altering environments through activities like agriculture, urban development, and conservation efforts, thereby influencing the balance and health of ecosystems. 2. Do you hold any particular feelings for producers? Consumers? Decomposers? Answer: Producers, such as plants, are essential as they form the base of the food chain, providing energy for all other organisms. Consumers, including humans, depend on these producers and each other for sustenance. Decomposers play a crucial role in recycling nutrients, maintaining soil health, and supporting the continuation of life. Each group is vital to ecosystem function and balance. 3. How do you feel when you think of a coyote eating a rabbit? How do you feel when you think of humans eating hamburgers? Answer: A coyote eating a rabbit reflects the natural predator-prey relationship essential for ecosystem balance. Similarly, humans eating hamburgers are part of our dietary habits, but it raises considerations about ethical treatment of animals, sustainability, and environmental impact. Both scenarios highlight the interdependence and sometimes complex dynamics of food webs. 4. Do humans have a right to domesticate and eat other species? Answer: Humans have historically domesticated and eaten other species for survival and cultural reasons. However, this practice comes with ethical considerations regarding animal welfare, environmental impact, and sustainability. Many argue that with the capability to make choices, humans also have a responsibility to ensure humane treatment and sustainable practices. 5. Do you feel there will always be enough matter and energy for the survival of all individuals of all species? Will the carrying capacity of the Earth be expanded by new technologies? Will nature be able to continually absorb "waste-products" from human societies? Answer: The finite nature of Earth's resources and energy means that there are limits to the survival of all individuals of all species. While new technologies may expand Earth's carrying capacity, they also bring challenges. Nature's ability to absorb waste is limited, and without sustainable practices, the degradation of ecosystems and depletion of resources will continue. 6. Do you feel any responsibility to protect natural ecosystems? Would you support the preservation of representative ecosystems? If so, on what basis? Answer: Yes, there is a responsibility to protect natural ecosystems to maintain biodiversity, ecosystem services, and the health of the planet. Preserving representative ecosystems is crucial for research, education, and cultural and aesthetic values. This protection can be based on ethical considerations, the need for sustainable resource management, and the recognition of the intrinsic value of nature. Additional Video Resources Blue Planet (Video series from Discovery Channel, 2001) Mammoth series, five years in the making, taking a look at the rich tapestry of life in the world's oceans. http://dsc.discovery.com/convergence/blueplanet/blueplanet.html The Habitable Planet: A Systems Approach to Environmental Science, videos 2, 3, 4, 9, and 12 (Documentary series, 2007). The videos in this series focus on atmosphere, oceans, ecosystems, biodiversity decline and earth’s changing climate. http://www.learner.org/resources/series209.html Journey to Planet Earth (Video series from PBS, 2003) http://www.pbs.org/journeytoplanetearth/ The Living Planet — A Portrait of the Earth (hosted by David Attenborough – four discs) This series discusses the biomass and life in a variety of ecosystems spanning many of the environments found on Earth. Planet Earth (BBC Series, 5 discs) An exploration of global ecosystems. http://www.bbc.co.uk/nature/animals/planetearth/ Web Resources The Hydrologic Cycle Interactive exploration of various phases of the water cycle. http://polaris.umuc.edu/cvu/envm/hydro/hydro.html Suggested Answers to End of Chapter Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 55. What are three harmful effects resulting from the clearing and degradation of tropical rain forests? Answer: • It will reduce the earth’s vital biodiversity by destroying or degrading the habitats of many of the unique plant and animal species found in these forests, thereby causing their premature extinction. • It will help to accelerate global warming, and thus climate change, by eliminating large areas of trees faster than they can grow back, thereby degrading the forests’ abilities to remove the greenhouse gas carbon dioxide (CO2) from the atmosphere. • It will change regional weather patterns in ways that can prevent the return of diverse tropical rain forests in cleared or degraded areas. Once this irreversible ecological tipping point is reached, tropical rain forests in such areas will become less diverse tropical grasslands. 2. Distinguish among the atmosphere, troposphere, stratosphere, stratosphere, hydrosphere, geosphere, and biosphere. What are greenhouse gases and why are they important? What three interconnected factors sustain life on earth? Answer: • The atmosphere is a thin spherical envelope of gases surrounding the earth’s surface. Its inner layer, the troposphere, extends only about 17 kilometers (11 miles) above sea level at the tropics and about 7 kilometers (4 miles) above the earth’s north and south poles. It contains the majority of the air that we breathe, consisting mostly of nitrogen (78% of the total volume) and oxygen (21%). The remaining 1% of the air includes water vapor, carbon dioxide, and methane, all of which are called greenhouse gases, which absorb and release energy that warms the lower atmosphere. Without these gases the earth would be too cold for the existence of life as we know it. Almost all of the earth’s weather occurs within this layer. The next layer, stretching 17–50 kilometers (11–31 miles) above the earth’s surface, is called the stratosphere. Its lower portion holds enough ozone (O3) gas to filter out most of the sun’s harmful ultraviolet (UV) radiation. This global sunscreen allows life to exist on land and in the surface layers of bodies of water. The hydrosphere consists of all of the water on or near the earth’s surface. It is found as liquid water (on the surface and underground), ice (polar ice, icebergs, and ice in frozen soil layers called permafrost), and water vapor in the atmosphere. The oceans, which cover about 71% of the globe, contain about 97% of the earth’s water. The geosphere consists of the earth’s intensely hot core, a thick mantle composed mostly of rock, and a thin outer crust. The biosphere consists of all of the parts of the atmosphere, hydrosphere, and geosphere where life is found. • Greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. They are responsible for warming the earth and making it inhabitable. • Three factors sustain the earth’s life. ○ The one-way flow of high-quality energy from the sun, through living things in their feeding interactions, into the environment as low-quality energy (mostly heat dispersed into air or water at a low temperature), and eventually back into space as heat. ○ The cycling of nutrients (the atoms, ions, or molecules needed for survival by living organisms) through parts of the biosphere. ○ Gravity allows the planet to hold onto its atmosphere and helps to enable the movement and cycling of chemicals through the air, water, soil, and organisms. 3. Describe the flow of energy to and from the earth. What is the natural greenhouse effect and why is it important for life on earth? Define ecology. Define organism, population, and community. Define and distinguish between an ecosystem and the biosphere. Answer: • About one-third of the incoming solar radiation is reflected back into space by clouds, particles in the atmosphere, and the earth’s surface. Another fifth of the incoming radiation is absorbed by ozone in the lower stratosphere (mostly UV radiation) and clouds and water vapor in the troposphere. Most of the remaining half of incoming solar radiation is absorbed by land and water on the earth’s surface. • Carbon dioxide and other gases in the troposphere lead to a warming of the troposphere known as the natural greenhouse effect. • Ecology is the biological science that studies how organisms, or living things, interact with one another and with their environment. • An organism is an individual living being. A population is a group of individuals of the same species that live in the same place at the same time. A community, or biological community, consists of all the populations of different species that live in a particular place. • An ecosystem is a community of different species interacting with one another and with their nonliving environment of matter and energy and the biosphere is the part of the earth's air, water, and soil where life is found. 4. Distinguish between the living and nonliving components in ecosystems and give two examples of each. Answer: • Biotic: consists of living biological components—plants, animals, and microbes. • Abiotic: consists of nonliving components such as water, air, nutrients, rocks, heat, and solar energy. 5. What is a trophic level? Distinguish among producers (autotrophs), consumers (heterotrophs), and decomposers and detritus feeders and give an example of each in an ecosystem. Distinguish among primary consumers (herbivores), secondary consumers (carnivores), tertiary (third-level) consumers, and omnivores, and give an example of each. Answer: • The trophic level, a feeding level, is the level assigned every type of organism in an ecosystem, depending on its source of food or nutrients. • Producers, sometimes called autotrophs (self-feeders), make the nutrients they need from compounds and energy obtained from their environment through a process called photosynthesis, a tree for example. • All organisms that are not producers are consumers, or heterotrophs (“other-feeders”), who cannot produce their own nutrients, a fox for example. • Decomposers are consumers that release nutrients from the dead bodies of plants and animals and return them to the soil, water, and air for reuse by producers, mushrooms for example. • Detritus feeders feed on the wastes or dead bodies of other organisms. Examples are earthworms, some insects, and vultures. • Primary consumers, or herbivores (plant eaters), are animals that eat producers, feeding mostly on green plants. Examples are caterpillars, deer, and zooplankton. • Carnivores (meat eaters) are animals that feed on the flesh of other animals. Some carnivores such as spiders, robins, and tuna are secondary consumers that feed on the flesh of herbivores. Other carnivores such as tigers, hawks, and killer whales (orcas) are tertiary (or higher) consumers that feed on the flesh of other carnivores. • Omnivores such as pigs, foxes, and humans can eat plants and other animals. 6. Distinguish between photosynthesis and chemosynthesis. Distinguish between aerobic respiration and anaerobic respiration (fermentation). What two processes sustain ecosystems and the biosphere and how are they linked? Explain the importance of microbes. Answer: • Producers use photosynthesis to convert CO2 into complex carbohydrates such as glucose (C6H12O6). Producers, consumers, and decomposers use the chemical energy stored in glucose and other organic compounds to fuel their life processes. In most cells, this energy is released by aerobic respiration, which uses oxygen to convert glucose (or other organic nutrient molecules) back into carbon dioxide and water. The net effect of the hundreds of steps in this complex process is represented by the following reaction: glucose +oxygen → carbon dioxide + water + energy. This linkage between photosynthesis in producers and aerobic respiration in producers, consumers, and decomposers circulates carbon in the biosphere. Oxygen and hydrogen—the other elements in carbohydrates—cycle almost in step with carbon. • A few producers, mostly specialized bacteria, can convert simple inorganic compounds from their environment into more complex nutrient compounds with-out using sunlight, through a process called chemosynthesis. • Some decomposers get the energy they need by breaking down glucose (or other organic compounds) in the absence of oxygen. This is called anaerobic respiration, or fermentation. The end products of this process are compounds such as methane gas ( CH4, the main component of natural gas), ethyl alcohol (C2H6O), acetic acid ( C2H4O2, the key component of vinegar), and hydrogen sulfide ( H2S, when sulfur compounds are broken down). • Ecosystems and the biosphere are sustained through a combination of one- way energy flow from the sun through these systems and nutrient cycling of key materials within them— two important natural services that are components of the earth’s natural capital. • Microbes that decompose dead and decaying plant and animal materials are vital to all ecosystems. Their importance is often ignored, but without them life would not exist. They consist of many different types of bacteria and fungi that secrete enzymes that break down materials from other organisms into smaller components; this enables nutrients to be recycled through the ecosystem as they are taken up from the soil and water by the producers. 7. Distinguish between a food chain and a food web. Explain what happens to energy as it flows through the food chains and food webs. What is biomass? What is the pyramid of energy flow? Why are there more insects than tigers in the world? Answer: • A sequence of organisms, each of which serves as a source of food or energy for the next, is called a food chain. Organisms in most ecosystems form a complex network of interconnected food chains called a food web. • Each trophic level in a food chain or web contains a certain amount of biomass. In a food chain or web, chemical energy stored in biomass is transferred from one trophic level to another. With each transfer, some energy is lost as low-quality heat. As energy flows through ecosystems in food chains and webs, there is a decrease in the amount of chemical energy available to organisms at each succeeding feeding level. • Biomass is the dry weight of all organic matter contained in its organisms. • The pyramid of energy flow assumes a 90% energy loss with each transfer in a food chain. • There is such a sharp reduction of energy as we move up trophic levels that there is simply not enough energy at the top to support large populations of top predators such as tigers. At the bottom level, however, there is plenty of energy to support large populations of insects. 8. Distinguish between gross primary productivity (GPP) and net primary productivity (NPP), and explain their importance. Answer: • Gross primary productivity (GPP) is the rate at which an ecosystem’s producers (usually plants) convert solar energy into chemical energy in the form of biomass found in their tissues. Net primary productivity (NPP) is the rate at which producers use photosynthesis to produce and store chemical energy minus the rate at which they use some of this stored chemical energy through aerobic respiration. The amount, or mass, of living organic material (biomass) that a particular ecosystem can support is determined by how much solar energy its producers can capture and store as chemical energy and by how rapidly they can do so. 9. What happens to matter in an ecosystem? What is a biogeochemical cycle (nutrient cycle)? Describe the hydrologic, or water cycle. Summarize the unique properties of water. Explain how clearing a rainforest can affect local weather (Core Case study). Explain how human activities are affecting the water cycle. Describe the carbon, nitrogen, phosphorus, and sulfur cycles and explain how human activities are affecting each cycle. Explain how nutrient cycles connect past, present, and future life. Answer: • Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere, and human activities are altering these chemical cycles. • The elements and compounds that make up nutrients move continually through air, water, soil, rock, and living organisms within ecosystems in cycles called biogeochemical cycles (literally, life-Earth-chemical cycles), or nutrient cycles. • The hydrological cycle, or water cycle, collects, purifies, and distributes this supply of water. • Water is necessary for life on the earth, and there is a fixed supply of it on our planet. Hydrogen bonds. ○ Exists as a liquid over a wide temperate range. ○ Stores a large amount of heat. ○ Dissolves a variety of compounds. ○ Filter’s some UV rays from the sun. ○ Capillary action. ○ Expands when freezes. ○ Exists in all three phases at the Earth’s surface • The vegetation in forests is the primary source of local rainfall. • Over land, about 90% of the water that reaches the atmosphere evaporates from the surfaces of plants, through a process called transpiration, and from the soil. • We alter the hydrologic cycle by extracting water from streams, clearing vegetation and altering wetlands. • Carbon is the basic building block of the carbohydrates, fats, proteins, DNA, and other organic compounds necessary for life. In the carbon cycle, carbon circulates through the biosphere, the atmosphere, and parts of the hydrosphere. We alter this cycle by adding large amounts of carbon to the atmosphere. • Nitrogen is a crucial component of proteins, many vitamins, and nucleic acids such as DNA. We alter this cycle by burning fossil fuels, clearing forests, and fertilizing our crops. • Phosphorus circulates through water, the earth’s crust, and living organisms in the phosphorus cycle. We alter this cycle by removing phosphate from the environment to make fertilizers. • Sulfur circulates through the biosphere in the sulfur cycle. We alter this cycle primarily by burning fossil fuels • The law of conservation of matter tells us that these nutrients cannot be destroyed, and so must be recycled. They are constantly cycled through living systems. 10. Describe three ways in which scientists study ecosystems. Describe how satellite and Google Earth technology can be used to help us understand and monitor the natural world and how we are affecting it. Explain why we need much more basic data about the structure and condition of the world’s ecosystems. What are this chapter’s three big ideas? How are the three principles of sustainability showcased in tropical rain forests? Answer: • Three approaches ecologists use to learn about ecosystems: field research, laboratory research, and ecosystem models. • Google Earth and satellites offer a snapshot of our most remote ecosystems. Those snapshots, taken over time can be used to monitor change, and thus our effect on ecosystems. • We need baseline data on the condition of the world’s ecosystems to see how they are changing and to develop effective strategies for preventing or slowing their degradation. • The three big ideas are that: ○ Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity, ○ Some organisms produce the nutrients they need, others survive by consuming other organisms, and some recycle nutrients back to producer organisms. ○ Human activities are altering the flow of energy through food chains and webs and the cycling of nutrients within ecosystems and the biosphere. • Producers within rain forests rely on solar energy to produce a vast amount of biomass through photosynthesis. Species living in the forests take part in, and depend on cycling of nutrients in the biosphere and the flow of energy through the biosphere. Tropical forests contain a huge and vital part of the earth’s biodiversity, and interactions among species living in these forests help to control the populations of the species living there. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. How would you explain the importance of tropical rainforests (Core Case Study) to people who think that such forests have no connections with their lives? Answer: Students might focus on the role these forests play as carbon sinks, tying up carbon that might otherwise contribute to climate change. Additionally, the biodiversity in rainforests affects the lives of people around the world because of the medicines that have been discovered there. And finally, weather patterns may be disrupted when the natural holding capacity of the forest is diminished and water simply runs off. Tropical rainforests are vital to our lives because they produce oxygen, regulate the climate, support biodiversity, and provide resources like medicine and food. They act as the Earth's lungs, sequestering carbon dioxide and helping stabilize global weather patterns. The loss of these forests can lead to climate change, loss of species, and depletion of natural resources, impacting everyone, even those far from the rainforest regions. 2. Explain why: (a) the flow of energy through the biosphere depends on the cycling of nutrients, and (b) the cycling of nutrients depends on gravity (Concept 3-1B). Answer: a. The earth is closed to significant inputs of matter and has a fixed supply of nutrients that must be recycled to support life. Energy flows through living things in their feeding interactions, the basic components of which are recycled when plants photosynthesize, making molecules of sugars to be consumed. b. Gravity holds the atmosphere close to the earth, and enables the cycling of chemicals through air, water, soil, and organisms. 3. Explain why microbes are so important. List two beneficial and two harmful effects of microbes on your health and lifestyle. Write a brief description of what you think would happen to you if microbes were eliminated from the earth. Answer: Microbes that decompose dead and decaying plant and animal materials are vital to all ecosystems. Their importance is often ignored but without them life would not exist. They consist of many different types of bacteria and fungi that secret enzymes that break down materials from other organisms into smaller components, and this enables nutrients to be recycled through the ecosystem as they are taken up from the soil and water by the producers. Two beneficial effects of microbes are their role in the recycling of matter and ensuring that there is no build-up of waste in the natural world. They are also used in the production of foods like cheese and yogurt. Two harmful effects of microbes are that they can cause diseases that can be detrimental to an individual’s health, and they can cause food to decay and be rendered unfit for human consumption. 4. Make a list of the food you ate for lunch or dinner today. Trace each type of food back to a particular producer species. Describe the sequence of feeding levels that led to your feeding. Answer: Student answers will vary but could include some of the following: if a student had a burger and fries for lunch the bread can be traced back to wheat, the meat to cows and the grain that was fed to them, the lettuce and tomatoes to the original plants, and the fries to potatoes. Lunch/Dinner: 1. Chicken Salad: • Producer: Lettuce (Lactuca sativa) • Sequence: Lettuce (Producer) → Chicken (Primary Consumer) → Human (Secondary Consumer) 2. Rice: • Producer: Rice plant (Oryza sativa) • Sequence: Rice plant (Producer) → Human (Primary Consumer) 3. Steamed Vegetables (Carrots, Broccoli): • Producers: Carrot (Daucus carota), Broccoli (Brassica oleracea) • Sequence: Vegetables (Producers) → Human (Primary Consumer) 5. Use the second law of thermodynamics (see Chapter 2, p. 47) to explain why many poor people in less-developed countries live on a mostly vegetarian diet. Answer: The second law of thermodynamics states that in any energy transformation, the energy quality will always decrease and we will end up with less usable energy than we began with. Much of the degraded energy is lost in the form of heat. Energy is lost at each trophic level in a food chain by as much as 90%. The earth can support more people if they ate at a lower level on the food chain by consuming grains, vegetables, and fruits directly. If these crops are fed to animals and pass through another trophic level, more energy is lost in the process. From an economic perspective it is also more costly to buy meat from cattle than it is to buy the grain that was used to feed them. People who live in rich developed countries can afford to live on a diet that is high in meat. However, people in poorer, less developed countries cannot afford to buy meat and live primarily on a vegetarian diet. In doing so they are behaving in a more energy efficient manner and in many cases a healthier one too. 6. Why do farmers not need to apply carbon to grow their crops but often need to add fertilizer containing nitrogen and phosphorus? Answer: The crops that farmers grow obtain the carbon that they need directly from the atmosphere in the form of carbon dioxide. As the atmosphere is all around us, the farmer does not have to apply carbon to the fields to grow crops. This is part of the gas phase of the naturally occurring biogeochemical carbon cycle. Although the nitrogen cycle has a gas phase, plants cannot obtain the nitrogen they need directly from the air and must get it in the form of inorganic nitrogen compounds produced in the soil by the nitrogen cycle. Often the farmer grows and harvests crops at such a rate that the nitrogen demand cannot be kept up with by the nitrogen cycle, and so additional nitrogen in the form of fertilizer has to be added to the field. Similarly, phosphate, which does not have a gas phase in its very slow biogeochemical cycle, has to be absorbed into plant crops from the soil in the form of phosphate ions. Again the farmer often grows and harvests crops at such a rate that the naturally occurring levels of phosphate in the soil are diminished. A fertilizer high in phosphates then has to be applied to the field to compensate. 7. What changes might take place in the hydrologic cycle if the earth’s climate becomes: (a) hotter, or (b) cooler? In each case explain how these changes might affect your lifestyle. Answer: (a) If the climate became hotter the hydrologic cycle could be adversely affected. The cycle could speed up and change global precipitation patterns, which in turn could affect the severity and frequency of storms, floods, and droughts. It could also enhance global warming by moving more water vapor into the atmosphere. An individual’s lifestyle could be affected by lack of water during droughts, too much water during floods causing landslides and mudslides, or increased exposure to disease causing organisms such as mosquitoes that reproduce in moist, humid climates that could result from increased rainfall in an area. (b) If the climate became cooler the hydrologic cycle could slow down and water would take more time to pass through this natural purification process. More freshwater could be trapped in the form of snow and ice in glaciers for a longer period of time, removing it from use for drinking, etc. by humans. Precipitation patterns could also change. A region may experience longer snow and ice coverage during winter, which could adversely affect the growing season in the area reducing the agricultural output. Another region may experience diminished rainfall, and water shortages could occur as aquifers are replenished at slower rates. Reduced water supplies has profound effects on the lifestyle of inhabitants of a region from not having enough drinking water to water rationing and bans on washing cars and watering lawns. 8. What would happen to an ecosystem if: (a) all its decomposers and detritus feeders were eliminated, (b) all its producers were eliminated, or (c) all of its insects were eliminated? Could a balanced ecosystem exist with only producers and decomposers and no consumers such as humans and other animals? Explain. Answer: (a) The ecosystem would not be able to recycle matter, and wastes would build up. Eventually other species would die as no nutrients would be released for plant growth, etc. The ecosystem would be doomed to collapse. (b) The producers form the base of the food chain, and if they were removed then herbivores and subsequently carnivores would eventually die out as they both depend on the producers for the energy that sustains them. The ecosystem would also collapse in this scenario. (c) Ecosystem collapse is inevitable if all insects were removed. Pollination would cease and plant growth would be severely affected. Insects are intrinsically linked to two principles of sustainability (renewable solar energy and recycling of nutrients). Insects play a vital role in implementing these two scientific principles. If these parts of an ecosystem’s function were removed, sustainability cannot be achieved and the ecosystem would become unbalanced and unstable. A fully functioning ecosystem is made up of producers, consumers, and decomposers all interacting with each other and the abiotic components of the environment. The greater the biodiversity of the ecosystem, the greater the balance, stability, and sustainability there is in the ecosystem. Could an ecosystem function with only producers and decomposers? Theoretically a plant could be grown and not eaten by any consumer, then die and be decomposed by bacteria and fungi. However, neither the producers nor the decomposers would function fully. Their role in the ecosystem would not be realized and the ecosystem would be out of balance. Consumers are vital to the sustainable functioning of the ecosystem, whether they are the animals that eat the producers, such as herbivores, or the animals that help decompose the producers, such as the detritus feeders. In order for a balanced ecosystem to exist, it needs all of the interacting components—producers, consumers, and decomposers. 9. List three ways you could apply Concept 3-3 and Concept 3-4 to making your lifestyle more environmentally sustainable. Answer: Answers may vary, but may include adopting a vegetarian diet, eating from lower trophic levels (especially in the case of many fish species that are top carnivores), and composting to recycle waste back into productive systems. 1. Reduce, Reuse, Recycle (Concept 3-3): Minimize waste by buying products with less packaging, reusing items, and recycling materials like paper, plastic, and glass. 2. Energy Conservation (Concept 3-3): Lower energy consumption by using energy-efficient appliances, switching to LED bulbs, and reducing unnecessary energy use. 3. Support Sustainable Products (Concept 3-4): Choose products made from renewable resources or those produced sustainably, such as organic foods, sustainably sourced wood, or eco-friendly cleaning products. 10. List two questions that you would like to have answered as a result of reading this chapter. Answer: 1. How can individuals more effectively contribute to biodiversity conservation in their daily lives? 2. What are the most significant challenges in achieving global sustainability, and how can they be addressed? Ecological Footprint Question Based on the following carbon dioxide emissions data and 2007 population data, answer the questions below. Country Total Carbon Footprint- Carbon Dioxide Emissions in Gigatonnes (109metric tons) (Gigatons (109 tons)) per year Population in billions (2007) Per Capita Carbon Footprint (Per Capita Carbon Dioxide Emissions per year) China 5.0 (5.5) 1.3 India 1.3 (1.4) 1.1 Japan 1.3 (1.4) 0.13 Russia 1.5 (1.6) 0.14 United States 6.0 (6.6) 0.30 WORLD 29 (32) 6.6 1. Calculate the per capita carbon footprint for each country and the world and complete the table. 2. It has been suggested that a sustainable average worldwide carbon footprint per person should be no more than 2.0 metric tons per person per year (2.2 tons per person per year). How many times larger is the U.S. carbon footprint per person than (a) the sustainable level, and (b) the world average? 3. By what percentage will China, Japan, Russia, the United States, and the world each have to reduce their carbon footprints per person to achieve the estimated maximum sustainable carbon footprint per person of 2.0 metric tons (2.2 tons) per person per year? Answer: 1. Country Total Carbon Footprint- Carbon Dioxide Emissions in Gigatonnes (109metric tons) [Gigatons (109short tons)] per year Population in billions (2007) Per Capita Carbon Footprint (Per Capita Carbon Dioxide Emissions per year) China 5.0 (5.5) 1.3 3.8 metric tons (4.2 tons]) India 1.3 (1.4) 1.1 1.2 metric tons (1.3 tons) Japan 1.3 (1.4) 0.13 10 metric tons (11 tons) Russia 1.5 (1.6) 0.14 11 metric tons (12 tons) United States 6.0 (6.6) 0.30 20 metric tons (22 tons) WORLD 29 (32) 6.6 4.4 metric tons (4.8 tons) 2. (a) How many times larger is the U.S. carbon footprint than the sustainable level? Answer: 20 metric tons CO2 /person/year = 10 times greater 2.00 metric tons CO2 /person/year 22 tons CO2 /person/year = 10 times greater 2.20 tons CO2 /person/year 2. (b) How many times larger is the U.S. carbon footprint than the world average? Answer: 2020 metric tons CO2/person/year = 4.5 times greater 4.4 metric tons CO2/person/year 22 tons CO2/person/year = 4.6 (4.58 times greater 4.8 tons CO2 /person/year 3. By what percentage will China, Japan, Russia, the United States, and the world each have to reduce their carbon footprints per person to achieve the estimated maximum sustainable carbon footprint per person of 2.0 metric tons (2.2 tons) per person per year? Answer: China: 3.8 metric tons per person – 2.0 metric tons per person = 1.8 metric tons per person 1.8 metric tons per person/3.8 metric tons per person x 100 = 47% Japan: 10 metric tons per person – 2.0 metric tons per person = 8.0 metric tons per person 8.0 metric tons per person/10 metric tons per person x 100 = 80% Russia: 11 metric tons per person – 2.0 metric tons per person = 9.0 metric tons per person 9.0 metric tons per person/11 metric tons per person x 100 = 82% United States: 20 metric tons per person – 2.0 metric tons per person = 18 metric tons per person 18 metric tons per person/20 metric tons per person x 100 = 90% World: 4.4 metric tons per person – 2.0 metric tons per person = 2.4 metric tons per person 2.4 metric tons per person/4.4 metric tons per person x 100 = 55% Chapter 4 Biodiversity and Evolution Summary 1. Evolution is the change in a population’s genetic makeup over time. Evolution forces adaptations to changes in environmental conditions in a population. The diversity of life on earth reflects the wide variety of adaptations necessary and suggests that environmental conditions have varied widely over the life of the earth. 2. An ecological niche is a species’ way of life or its functional role in a community. Everything that affects its survival and reproduction (temperature tolerance, water needs, space needs, interactions with other organisms, etc.) is a part of that niche. The ecological niche helps a population survive by the adaptive traits that its organisms have acquired. 3. Extinction of species and formation of new species constantly change the biodiversity of the earth. 4. In the future, evolution will continue to influence our environment. Man’s use of artificial selection and genetic engineering to evolve species may have unintended consequences because evolution is a long, slow process and is unpredictable. Key Questions and Concepts 4-1 What is biodiversity and why is it important? CORE CASE STUDY. Some sharks play the role of keystone species in their environments. Nevertheless, about 32% of shark species are threatened with extinction. In addition to the roles sharks play in their environments, science stands to learn many things from these species. Many people argue that they should be saved simply because they have the right to exist. A. Biodiversity is the variety of species, genes, ecosystems, and ecosystem processes. 1. Species are individuals that can make and produce viable offspring. 2. Species diversity, genetic diversity, ecosystem diversity, and functional diversity. a. Biomes are large regions with distinct climates and certain species that are adapted to them. Individuals Matter: E.O Wilson has been a large influence on conservation efforts. His early work included discovering how ants communicate and developing the theory of island biogeography. SCIENCE FOCUS: Insects often have a bad reputation and are considered pests. However the ecological roles they play in pollinating flowering plants and controlling other insect populations make them invaluable to humans. 4-2 How does the earth’s life change over time? A. Most of what we know of the history of life comes from the fossil record. B. Evolution is the change in a population’s genetic makeup over time. C. All species descend from earlier, ancestral species—theory of evolution. 1. In 1858 Charles Darwin and Alfred Russel Wallace independently proposed natural selection as the mechanism of evolution. 2. Natural selection occurs when members of a population have genetic traits that improve their ability to survive and produce offspring with those specific traits. 3. For natural selection to work on a population, three steps occur: a. The development of genetic variability. i. Mutations are random changes in the structure/number of DNA molecules in a cell. ii. Mutations occur in two ways. 1. Gene DNA is exposed to external agents like X-rays, chemicals (mutagens), or radioactivity. 2. Random mistakes that occur in coded genetic instructions. b. Natural selection: environmental conditions favor some individuals over others by virtue of adaptive traits. c. populations evolve such that they are better adapted to survive and reproduce under existing conditions. CASE STUDY. Humans have thrived so well as a species because of their strong opposable thumbs, ability to walk upright and complex brain. These adaptations may not prove as beneficial as the environment continues to change, though our powerful brain may allow us to live more sustainably in the future. 4. Natural selection can only act on existing genes and is limited by reproductive capacity. 5. Three common misconceptions about evolution. a. Fitness is a measure of strength. b. Organisms develop certain traits because they need them. c. Evolution works according to some grand plan. 4-3 How do geological processes and climate change affect evolution? A. Processes such as the shifting of tectonic plates, volcanic eruptions, and earthquakes influence earth’s climate and in turn affect evolution by removing and/or isolating habitats and species. B. Long-term climate changes relocate ecosystems, thus determining where certain species can live. C. Asteroids and meteorites have caused environmental stress and mass extinctions. SCIENCE FOCUS: Earth is uniquely suited to support life because of its average temperature, distance from the sun, size and atmospheric composition. 4-4 How do speciation, extinction, and human activities affect biodiversity? A. Natural selection can lead to development of an entirely new species. In speciation, two species arise from one when some members of a population cannot breed with other members to produce fertile offspring. Speciation occurs in two phases: 1. Geographic isolation, physical separation for long time periods. 2. Reproductive isolation. B. When population members cannot adapt to changing environmental conditions, the species becomes extinct. 1. Endemic species (those found in only one place) are especially vulnerable. C. When local environmental conditions change, some species will disappear at a low rate; this is called background extinction. D. Mass extinction is a significant rise in extinction rates above the background extinction level. Usually, 25–95% of species are lost. There appear to have been at least three and perhaps five mass extinctions on earth. SCIENCE FOCUS: Artificial selection involves crossbreeding between genetic varieties of the same species to give rise to populations with desirable traits. Now, scientists can use genetic engineering to produce desirable traits or eliminate undesirable ones. 4-5 What is species diversity and why is it important? A. Species diversity is the number of species (richness) combined with their relative abundance (evenness). B. Species rich communities tend to be more stable and more productive. SCIENCE FOCUS: The size of a habitat and its isolation affect the species richness of that habitat island. 4-6 What roles do species play in ecosystems? A. Ecological niche is a species’ way of life in an ecosystem, everything that affects its survival and reproduction. B. Some species have broad ecological roles and are termed generalist species. C. Some species have narrow ecological roles and are termed specialist species. CASE STUDY: Cockroaches are the ultimate generalists. The can survive extreme conditions and have a wide variety of adaptations that allow them to avoid predation. D. Niches can be occupied by native or non-native species. E. Indicator species provide early warning of ecosystem damage because they have a narrow range of tolerance. CASE STUDY: Amphibians are indicator species that are declining globally. Factors affecting their survival include habitat loss, drought, pollution, an increase in UV radiation, parasites, fungal diseases, climate change, overhunting, and introduction of non-native species. Their role as indicator species is cause for alarm on a global scale. H. Keystone species have a large effect on maintaining balance within an ecosystem. 1. Can be, but are not necessarily, pollinators and top predators. CASE STUDY: Alligators act as a keystone species, yet their numbers were seriously compromised by over-hunting. Their activities provide important habitat for fish and avian species. They also control populations by their feeding behaviors. In 1967 the alligator was placed on the endangered species list and has made a dramatic recovery. 2. Foundation species create and enhance habitats that benefit other species. Teaching Tips Large Lecture Courses: Pick two species that students would be familiar with from the local environment (perhaps something from the urban edge, such as coyotes or raccoons). One should be a generalist and one a specialist. Allow them to brainstorm ideas as you record them on the board. What are the characteristics of each? Which one are they more familiar with? Are humans more similar to the specialist or generalist? Smaller Lecture Courses Have students work in small groups researching a species that is an ecosystem engineer prior to this lecture. As an introduction, they can briefly present their species to the rest of the course, covering the ways in which the species alters its environment, and what advantages this has. Conclude with a compare/contrast discourse on the ways in which humans are similar or different from ecosystem engineers. Key Terms adaptation adaptive trait background extinction biological diversity biological evolution differential reproduction ecological niche endemic species extinction fossils foundation species generalist species geographic isolation indicator species keystone species mass extinction mutations native species natural selection niche nonnative species reproductive isolation specialist species speciation species species diversity theory of evolution Term Paper Research Topics 1. Evolution: the theory of evolution, supporting and detracting evidence, fossils; embryological homologies, structural homologies; biochemical evidence; DNA evidence. Contrast the views of slow, gradual change and relatively rapid (punctuated) change. 2. Biological Evolution: endosymbiont hypothesis; Gaia hypothesis; extinctions and radiations; natural selection and genetic drift; adaptations and their limits; gradualism and punctuated equilibrium. 3. Diversity of species: choose a kingdom. 4. Genetic engineering: how humans are changing the course of evolution. 5. Scientific methods: genetic engineering; DNA analysis. Discussion Topics 1. To what extent should humans take evolution into their own hands? Answer: Humans have already influenced evolution through selective breeding and biotechnology. While these advances offer potential benefits, such as disease prevention and agricultural improvements, ethical concerns about unintended consequences, biodiversity loss, and equity must be considered. The extent of intervention should be carefully managed, ensuring responsible use and consideration of long-term ecological impacts. 2. Should there be limits on genetic engineering? Answer: Yes, limits on genetic engineering are necessary to prevent potential ethical, ecological, and health risks. Regulations should ensure safety, prevent misuse, and address concerns like genetic privacy and consent. Ethical considerations, such as fairness, accessibility, and the potential for unintended consequences, must guide the responsible application of genetic technologies. 3. How does the change that humans create through cultural evolution compare to the process of evolution by natural selection? Answer: Cultural evolution involves the transmission and adaptation of knowledge, practices, and technologies within societies, occurring much faster than biological evolution by natural selection. While natural selection relies on genetic variation and environmental pressures over long timescales, cultural evolution allows for rapid, intentional change. However, cultural adaptations can also influence biological evolution, as seen in domestication and medical advancements. Activities/Projects 1. As a class exercise, evaluate the diversity of your community using criteria such as ethnic, racial, religious, and socioeconomic groups; lifestyles; and industries, landscape features, and landscape forms. What elements of diversity have proved troublesome? What additional elements of diversity would improve your community? 2. Invite an evolutionary biologist to your class. Ask about evidence for different parts of the theory of evolution, including the endosymbiont hypothesis. Ask about the Gaia hypothesis. 3. Arrange a field trip providing opportunities to compare and contrast ecosystems of several different types, including some damaged or stressed by human activities. Invite an ecologist or biologist along to identify and discuss specific examples of species adaptation to environmental conditions. Do the boundaries between different kinds of ecosystems tend to be sharply delineated? Can you identify factors that limit the growth of certain species? 4. As a class, consider the crops that provide the majority of our food. Brainstorm a list of "designer genes" that would improve those crops for human consumption. Reflect on how genetic engineering alters the relationship between humans and evolution. Consider the power and the limits of that relationship. Attitudes and Values 1. Do you think that biodiversity is an ecosystem service? Explain. Answer: Yes, biodiversity is an ecosystem service because it contributes to the functioning and resilience of ecosystems, providing benefits like pollination, water purification, climate regulation, and nutrient cycling. Diverse species interactions support ecosystem productivity and stability, making biodiversity crucial for human well-being and sustainable natural resource use. 2. Do you think you have a responsibility to sustain biodiversity? Answer: Yes, I believe we have a responsibility to sustain biodiversity. As humans, we rely on the ecosystem services provided by biodiversity for our survival and quality of life. Additionally, ethical considerations about the intrinsic value of all species and the moral obligation to preserve the planet for future generations underscore our duty to protect and sustain biodiversity. 3. Do you think evolution of species has occurred? If so, how? Answer: Yes, the evolution of species has occurred. Evolution is the process by which species change over time through mechanisms such as natural selection, genetic drift, mutation, and gene flow. These processes lead to adaptations that help organisms survive and reproduce in their environments, resulting in the diversification of life forms seen on Earth today. 4. Do you think species have a right to struggle to survive without human interference? Answer: Yes, species have a right to struggle to survive without human interference. This perspective recognizes the intrinsic value of all life forms and respects the natural processes that govern ecosystems. While humans have a significant impact on the environment, allowing species to exist and evolve independently preserves biodiversity and maintains the balance of ecosystems. News Videos Circle of Life; Environmental Science in the Headlines, 2008, DVD ISBN: 0495561908 Global Warning: Where Have the Wild Things Gone? Environmental Science in the Headlines, 2008, DVD ISBN: 0495561908 Bald Eagle Soars Again: Taken Off Endangered Species List; Environmental Science in the Headlines, 2008, DVD ISBN: 0495561908 Darwin’s Galapagos Under Threat; The Brooks/Cole Environmental Science Video Library, 2009; DVD ISBN: 0538733551 Additional Video Resources Beavers: IMAX (1998) An engaging look at the charismatic ecosystem engineers. http://www.imax.com/ImaxWeb/filmDetail.do?type=nowPlaying&movieID=code__.__12667 The Habitable Planet: A Systems Approach to Environmental Science, Many planets, One Earth (Documentary series, 2007). This segment looks at clues to help explain the rise of complex animal life on earth. http://www.learner.org/resources/series209.html Nova—Evolution: Extinction! Main Website: http://www.pbs.org/wgbh/evolution/extinction/ Teachers Guide: http://www.pbs.org/wgbh/nova/teachers/programs/0000_evoextin.html Planet Earth (BBC Series, 5 discs) An exploration of global ecosystems. http://www.bbc.co.uk/nature/animals/planetearth/ Web Resources IUCN Red List The IUCN Species Survival Commission’s list of threatened and endangered species around the globe. http://www.iucnredlist.org Encyclopedia of Life An attempt to document all species of life on earth. http://www.eol.org Suggested Answers to End of Chapter Questions Review Questions 1. Review the Key Questions and Concepts for this chapter on p. 81. Describe the threats to many of the world’s shark species (Core Case Study) and explain why we should protect sharks from extinction as a result of our activities. Answer: • Sharks are victim to our misconceptions about them. Many people fear sharks and for that reason they have been hunted and killed in many cases to the point of being threatened with extinction. Many sharks, however, act as keystone species in their ecosystems, so they are vitally important. 2. What are the four major components of biodiversity (biological diversity)? What is the importance of biodiversity? What are species? Describe the importance of insects. Define and give three examples of biomes. Answer: • Biological diversity, or biodiversity, is the variety of the earth’s species, the genes they contain, the ecosystems in which they live, and the ecosystem processes such as energy flow and nutrient cycling that sustain all. • Biodiversity is a vital renewable resource. • A species is a set of individuals that can mate and produce fertile offspring. • Insects are pollinators and help sustain life on earth. • Biomes are large regions with distinct climates and a set of species that are adapted to that climate. Examples include forests, deserts, and grasslands. 3. What is a fossil and why are fossils important in understanding the history of life? What is biological evolution? Summarize the theory of evolution. What is natural selection? What is a mutation and what role do mutations play in evolution by natural selection? What is an adaptation (adaptive trait)? What is differential reproduction and why is it important? How did we become such a powerful species? What are two limits to evolution by natural selection? What are three myths about evolution through natural selection? Answer: • Fossils are mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds, or impressions of such items found in rocks that help to tell us the history of the earth. • Biological evolution is the process whereby Earth’s life changes over time through changes in the genetic characteristics of populations. • The theory of evolution holds that all species descended from earlier, ancestral species. In other words, life comes from life. • Natural selection is the process in which individuals with certain traits are more likely to survive and reproduce under a particular set of environmental conditions than those without the traits. • Mutations are random changes in the DNA molecules of a gene in any cell. Mutations can result from random changes that occur spontaneously within a cell or from exposure to external agents, such as radioactivity. Mutations can occur in any cell, but only those taking place in genes of reproductive cells are passed on to offspring. Sometimes such a mutation can result in a new genetic trait, called a heritable trait, which can be passed from one generation to the next. In this way, populations develop differences among individuals, including genetic variability. • Adaptation, or adaptive trait, is any heritable trait that improves the ability of an individual organism to survive and to reproduce at a higher rate than other individuals in a population can under prevailing environmental conditions. • For natural selection to occur, individuals with adaptive traits must have differential reproduction, which enables individuals with the trait to leave more offspring than other members of the population leave. • Human success is attributed to three adaptations: strong opposable thumbs that allow us to grip and use tools better than the few other animals that have thumbs; an ability to walk upright, which gives us agility and frees up our hands for many uses; and a complex brain, which has allowed us to develop many skills, including the ability to use speech to transmit complex ideas. • Two limits to evolution by natural selection include: a change in environmental conditions, which can lead to such an adaptation only for genetic traits already present in a population’s gene pool, or for traits resulting from mutations; and even if a beneficial heritable trait is present in a population, the population’s ability to adapt may be limited by its reproductive capacity. • Three misconceptions: ○ “Survival of the fittest” means “survival of the strongest.” ○ Organisms develop certain traits because they need them. ○ Evolution by natural selection involves some grand plan of nature in which species become more perfectly adapted. 4. Describe how geologic processes can affect natural selection. How can climate change and catastrophes such as asteroid impacts affect natural selection? Describe conditions on the earth that favor the development of life as we know it. Answer: • Tectonic plate movements, volcanic eruptions and earthquakes have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species. • Climate change and asteroids have shifted the locations of ecosystems and created opportunities for evolution. • Life on the earth, as we know it, can thrive only within a certain temperature range, which depends on the liquid water that dominates the earth’s surface. 5. What is speciation? Distinguish between geographic isolation and reproductive isolation and explain how they can lead to the formation of a new species. Distinguish between artificial selection and genetic engineering and give an example of each. Answer: • Speciation is when one species splits into two or more different species. For sexually reproducing organisms, a new species is formed when one population of a species has evolved to the point where its members no longer can breed and produce fertile offspring with members of another population that did not change or that evolved in a different way. • Geographic isolation occurs when different groups of the same population of a species become physically isolated from one another for a long period of time. For example, part of a population may migrate in search of food and then begin living as a separate population in another area with different environmental conditions. Populations can also be separated by a physical barrier (such as a mountain range, stream, or road), a volcanic eruption, tectonic plate movements, or winds or flowing water that carry a few individuals to a distant area. In reproductive isolation, mutation and change by natural selection operate independently in the gene pools of geographically isolated populations. • Artificial selection enables a change in the genetic characteristics of populations by selecting one or more desirable genetic traits in the population of a plant or animal such as a type of wheat, fruit, or dog. Then selective breeding is used to generate populations of the species containing large numbers of individuals with the desired traits. Genetic engineering is the alteration of an organism’s genetic material through adding, deleting, or changing segments of its DNA to produce desirable traits or eliminate undesirable ones. It enables scientists to transfer genes between different species that would not interbreed in nature. For example, genes from a fish species can be put into a tomato plant to give it certain properties. Scientists have used genetic engineering to develop modified crop plants, new drugs, pest-resistant plants, and animals that grow rapidly. 6. What is extinction? What is an endemic species and why can such a species be vulnerable to extinction? Distinguish between background extinction and mass extinction. Answer: • Extinction is a process in which an entire species ceases to exist (biological extinction) or a population of a species becomes extinct over a large region, but not globally (local extinction). • Species that are found in only one area are called endemic species and are especially vulnerable to extinction because they are unlikely to be able to migrate or adapt in the face of rapidly changing environmental conditions. • Throughout most of the earth’s long history, species have disappeared at a low rate, called background extinction. Mass extinction is a significant rise in extinction rates above the background level. In such a catastrophic, widespread, and often global event, large groups of species (25–95% of all species) are wiped out worldwide in a few million years or less. 7. What is species diversity? Distinguish between species richness and species evenness and give an example of each. Describe the theory of island biogeography (species equilibrium model). According to this theory, what two factors affect the immigration and extinction rates of species on an island? What are habitat islands? Explain why species-rich ecosystems tend to be productive and sustainable. Answer: • An important characteristic of a community and the ecosystem to which it belongs is its species diversity: the number of different species it contains (species richness) combined with the relative abundance of individuals within each of those species (species evenness). • A biologically diverse community such as a tropical rain forest or a coral reef with a large number of different species (high species richness) generally has only a few members of each species ( low species evenness). A single tree in a tropical forest in Panama may house an estimated 1,700 different beetle species but only a few individuals of each species. In contrast, an aspen forest community in Canada may have only a few plant species (low species richness) but large numbers of each species (high species evenness). • The theory of island biogeography, or species equilibrium model, is a widely accepted scientific theory that states that the number of different species (species richness) found on an island is determined by the interactions of two factors: the rate at which new species immigrate to the island and the rate at which species become extinct, or cease to exist, on the island. The model projects that, at some point, the rates of species immigration and species extinction should balance so that neither rate is increasing or decreasing sharply. This balance point is the equilibrium point that determines the island’s average number of different species (species richness) over time. • The two factors affecting immigration and extinction are island size and isolation. • Habitat islands are areas of habitat surrounded by a fragmented landscape. • Species diversity is a major component of biodiversity and tends to increase the sustainability of some ecosystems. Research suggests that species richness affect an ecosystem because plant productivity is higher in species- rich ecosystems and species richness enhances the stability, or sustainability of an ecosystem. 8. What is an ecological niche? Distinguish between specialist species and generalist species and give an example of each. Why do some scientists consider the cockroach to be one of evolution’s greatest success stories? Answer: • An important principle of ecology is that each species has a specific role to play in the ecosystems where it is found. Scientists describe the role that a species plays in its ecosystem as its ecological niche, or simply niche. It is a species’ way of life in a community and includes everything that affects its survival and reproduction, such as how much water and sunlight it needs, how much space it requires, and the temperatures it can tolerate. • Generalist species have broad niches. They can live in many different places, eat a variety of foods, and often tolerate a wide range of environmental conditions. Flies, cockroaches, mice, rats, white-tailed deer, raccoons, and humans are generalist species. • Specialist species occupy narrow niches. They may be able to live in only one type of habitat, use one or a few types of food, or tolerate a narrow range of climatic and other environmental conditions. For example, tiger salamanders breed only in fishless ponds where their larvae will not be eaten. • Cockroaches are excellent generalists that can survive in and colonize nearly any environment on earth. 9. Distinguish among native, nonnative and indicator species and give an example of each type. What major ecological roles do amphibian species play? List nine factors that help to threaten the health of frogs and other amphibians with extinction. What are three reasons for protecting amphibians? Distinguish between keystone and foundation species. Describe the role of some sharks as keystone species. Describe the role of the American alligator as a keystone species and how it was brought back from near extinction. Describe the role of beavers as a foundation species. Answer: • Native species are those species that normally live and thrive in a particular ecosystem. Other species that migrate into, or are deliberately or accidentally introduced into, an ecosystem are called nonnative species, also referred to as invasive, alien, and exotic species. The African bee would be native to Africa but a nonnative to Brazil. • Species that provide early warnings of damage to a community or an ecosystem are called indicator species. The presence or absence of trout species in water at temperatures within their range of tolerance is an indicator of water quality because trout need clean water with high levels of dissolved oxygen. • Amphibians help to control insect populations. • Nine factors: ○ Habitat loss ○ Drought ○ Increases in UV radiation ○ Parasites ○ Viral and fungal diseases ○ Pollution ○ Climate change ○ Overhunting ○ Non-native species • Three reasons: ○ They are indicator species. ○ They control insect populations. ○ They are a storehouse of pharmaceutical chemicals. • Keystone species are species whose roles have a large effect on the types and abundances of other species in an ecosystem (e.g., the American Alligator). • Foundation species play a major role in shaping communities by creating and enhancing their habitats in ways that benefit other species. For example, elephants push over, break, or uproot trees, creating forest openings in the woodlands of Africa. • Birds are excellent indicator species because they are found almost everywhere and are affected quickly by environmental changes, such as loss or fragmentation of their habitats and introduction of chemical pesticides. • Some sharks are keystone species, helping to remove injured and sick animals from the oceans. • As most American alligators were eliminated from their natural areas in the 1950s, scientists began pointing out the ecological benefits these animals had been providing to their ecosystems (such as building water holes, nesting mounds, and feeding sites for other species). Since that time, they were placed on the endangered species list, and their numbers have increased dramatically. • Beavers are another good example of a foundation species. Acting as “ecological engineers,” they build dams in streams to create ponds and other wetlands used by other species. Some bat and bird foundation species help to regenerate deforested areas and spread fruit plants by depositing plant seeds in their droppings. 10. What are this chapter’s three big ideas? How are ecosystems and the variety of species they contain related to the three principles of sustainability? Answer: • Three big ideas: ○ Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection). ○ Human activities are decreasing the earth’s vital biodiversity by causing the extinction of species and by disrupting habitats needed for the development of new species. ○ Each species plays a specific ecological role (ecological niche) in the ecosystem where it is found. • Ecosystems are storehouses of biodiversity that are solar powered and that recycle matter. Ecosystems are a model for sustainability. Critical Thinking The following are examples of the material that should be contained in possible student answers to the end of chapter Critical Thinking questions. They represent only a summary overview and serve to highlight the core concepts that are addressed in the text. It should be anticipated that the students will provide more in-depth and detailed responses to the questions depending on an individual instructor’s stated expectations. 1. How might we and other species be affected if all of the world’s sharks were to go extinct? Answer: The ecosystem would be very much altered because sharks act as keystone species. Some species of shark play crucial roles in keeping their ecosystems functioning by feeding at the top of the food web and ridding the ecosystem of injured and sick animals. Without this service, the food web would be greatly altered. 2. What role does each of the following processes play in helping implement the four scientific principles of sustainability: (a) natural selection, (b) speciation, and (c) extinction? Answer: (a) Natural selection implements all four principles of sustainability. Solar energy produces the plants that provide the energy and food for a great biodiversity of creatures living on the planet. Predator-prey relationships help to maintain the “survival of the fittest” implications in natural selection and control population. The nutrients in the remains of the prey then get recycled back through the system. (b) Speciation impacts the biodiversity principle of sustainability. The more new species arise as a result of speciation, the greater the biodiversity of the ecosystem. If the new species is a predator it could also impact the population control principle of sustainability. (c) Extinction results directly in a loss of biodiversity as the species is lost from the gene pool. The nutrients in the species will be recycled through the ecosystem as the numbers decline until no more of the species are left. If the species that has become extinct was a predator species, then it could also impact the population control principle of sustainability. 3. How would you respond to someone who tells you: (a) that he or she does not believe in biological evolution by natural selection because it is “just a theory,” and (b) that we should not worry about air pollution because natural selection will enable humans to develop lungs that can detoxify pollutants? Answer: (a) A theory is part of the process that scientists follow when investigating scientific evidence in order to explain their observations. For a theory to be validated it has to be accepted by the scientific community and reviewed by the world’s leading scientists. It has to stand up to scientific scrutiny. There is much fossil evidence to indicate that evolution through natural selection has taken place. There are also some examples that evolution is in action today as evidenced by the color changes in moths that has taken place since the industrial revolution. Indeed, evolution may just be a theory, but to date the theory has stood the test of time within the scientific world. Until a better scientific explanation is put forward it will remain the explanation of choice. Physicists and mathematicians give credence to the theory of relativity, because as yet no one has proven it wrong. Even Einstein said that a thousand experiments can prove him right, but it would take only one experiment to prove him wrong. As yet, that experiment has not been conducted so the theory of relativity, like the theory of evolution, remains the best scientific explanation of our observations. (b) Unfortunately, with the human species and other large species that do not reproduce large numbers of offspring rapidly, natural selection will not take place quickly enough for our lungs to become resilient to air pollution. Maybe this adaptation could take place over thousands or even millions of years, but in someone’s own lifespan this is not feasible. It is more feasible to tackle the problem of air pollution and bring about its reduction, than it is to assume that humans will be able to adapt to these undesirable environmental conditions in the short term. 4. Describe the major differences between the ecological niches of humans and cockroaches. Are these two species in competition? If so, how do they manage to coexist? Answer: Both cockroaches and humans are generalist species having very broad niches. This means that they can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Cockroaches have been around for 350 million years and have thrived throughout the evolutionary process. Humans are a recent addition to the planet. Cockroaches eat almost anything and can live anywhere except in the polar regions. They can go for a month without food, survive for a month on one drop of water, and can withstand high doses of radiation. Some cockroaches can even survive being frozen. These traits are in contrast to humans. Additionally humans do not reproduce as fast as cockroaches, which have a very high reproductive rate. Unlike humans, cockroaches also eat their own dead, and if food is scarce will even eat each other! Although cockroaches do live in homes that are occupied by humans, they are not directly in competition with each other for resources. However, cockroaches can evade been stepped on, as they have rapid response times, and the ability to see virtually in all directions at once. Cockroaches carry bacteria and viruses that cause diseases in humans, and can cause allergic responses in susceptible individuals. 5. How would you experimentally determine whether an organism is (a) a keystone species and (b) a foundation species? Answer: (a) A controlled experiment could be performed similar to the one conducted by Robert Paine on the rocky shoreline of the Pacific coast of Washington State. He demonstrated the keystone role of the top-predator sea star Piaster orchaceus in an intertidal zone community. Paine removed these mussel-eating sea stars from one rocky shoreline community but not from an adjacent community, which served as the control group. Mussels took over and crowded out many other species in the community without the Piaster sea stars. This type of experiment could be performed in other areas, with different species, to assess the role that certain species have in an ecosystem and whether a species could be classified as a keystone species. (b) Similarly, a removal experiment could be designed in a region to assess if the absence of a species leads to significant changes in the overall environment. Foundation species effectively engineer their environment to provide new and different habitats. In their absence, these alterations would not occur and the relative abundance or species dependent upon the altered landscape would change. 6. Is the human species a keystone species? Explain. If humans were to become extinct, what are three species that might also become extinct and three species whose population would probably grow? Answer: Humans are likely a keystone species by virtue of their technology and the extreme manner in which they influence their habitat. Were we to become extinct, their domesticates would most likely not survive. These would include pets, livestock, and crop plants. Species whose populations would likely grow would be the ones human activities have had a detrimental effect on, such as whales, mountain gorillas, and the many weeds we struggle to keep in check. 7. How would you respond to someone who says that because extinction is a natural process, we should not worry about the loss of biodiversity when species become extinct as a result of our activities? Answer: It is true that as environmental conditions change some species may begin to disappear at a low rate. This is the background extinction rate, and annually is around one to five species for every million species on the planet. However, scientists such as E. O. Wilson suggest that human activities have increased the extinction rate to somewhere between 100 and 1000 times the natural background rate. As more and more habitat is disturbed by human use and the resulting declines in biodiversity take place, we could lose many species from the earth over a relatively small time scale. Tropical rain forests, coral reefs, and wetlands are some of the most biodiverse areas on the earth, yet these are the regions that are under the most threat. Loss of biodiversity in these regions will have a major effect on the ecosystems and bring about extinction rates that are well above the naturally occurring background rates. 8. List three ways you could apply concept 4-4B in order to live a more environmentally sustainable lifestyle. Answer: Answers may vary. Students may suggest that they would attempt to limit the effects of habitat fragmentation by planting native vegetation in their yards in order to create or contribute to a habitat corridor. They could limit the extent to which their economic activities support deforestation and habitat loss in foreign countries. They might also pursue political activity to oppose massive habitat loss through the conversion of land into agriculture or suburban land uses. Concept 4-4B likely refers to an idea related to behavioral change or decision-making for environmental sustainability. Here are three ways to apply such a concept: 1. Adopt Eco-Friendly Habits: Reduce personal waste by recycling, composting, and minimizing single-use plastics. 2. Make Informed Purchases: Choose products with eco-friendly certifications or minimal packaging. 3. Support Sustainable Practices: Support businesses and policies that prioritize sustainability and environmental responsibility. 9. Congratulations! You are in charge of the future evolution of life on the earth. What are the three things that you would consider to be the most important to do? Answer: Student answers will vary but could include: increased conservation, preservation, and protection of habitat that allows for greater biodiversity and ecosystem stability through continuing evolutionary processes; learn how to work and live within the four principles of sustainability and apply these to the human ecosystem; and address some of the main anthropogenic causes of environmental degradation and take measures to remedy these issues expediently to offset the negative effects that they may have on the evolution of species-global warming, ozone thinning, etc. 1. Promote Biodiversity: Protect and restore natural habitats to ensure the survival of diverse species and ecosystems. 2. Combat Climate Change: Implement strategies to reduce greenhouse gas emissions and adapt to changing environmental conditions. 3. Advance Sustainable Practices: Encourage sustainable agriculture, renewable energy, and responsible consumption to maintain ecological balance. 10. List two questions that you would like to have answered as a result of reading this chapter. Answer: 1. What are the most effective strategies for promoting biodiversity conservation on a global scale? 2. How can we balance economic development with environmental sustainability to ensure long-term ecological health? Data Analysis This graph shows data collected by scientists investigating island biogeography. It shows measurements taken for two variables: the area within which measurements were taken and the population density of a certain species of lizard found in each area. Note that the areas studied varied from 100 square meters (m2) (1,076 square feet) to 300 m2 (3,228 square feet) (x-axis). Densities measured varied from 0.1 to 0.4 individuals per m2 (y-axis). Study the data and answer the following questions. 1. How many measurements below 0.2 individuals per m2 were made? How many of these measurements were made in areas smaller than 200 m2? How many were made in areas larger than 200 m2? Answer: • 4 • 3 • 1 2. How many measurements above 0.2 individuals per m2 were made? How many of these measurements were made in areas smaller than 200 m2? How many were made in areas larger than 200 m2? Answer: • 8 • 3 • 5 3. Do your answers support the hypothesis that larger islands tend to have higher species densities? Explain. Answer: • Yes, this data indicates a trend that larger islands tend to have higher species densities, and thus lends support (fails to refute) the hypothesis. Solution Manual for Living in the Environment: Principles, Connections, and Solutions G. Tyler Miller, Scott Spoolman 9780538735346