CorrectionKey AL-A SECTION 13.1 Alabama Course Of 13.1 Ecologists Study .

CorrectionKey AL-A C MAIN IDEA . Teach continued Ecological research methods include observation, experimentation, and modeling. History of Science Scientists rely on a variety of methods and tools to conduct research. Tools can range from a simple tape measure used to find an organism’s size to a sophisticated computer system used to create a model of an entire ecosystem. During the 1700s and 1800s, many scientists, including Charles Darwin and Alfred Russell Wallace, traveled to different parts of the world to catalog new species. The work of Darwin and Wallace made clear the connection between the physical characteristics of a place and the types of species found there—biogeography. The British botanist Arthur Tansley coined the word ecosystem in 1935 to describe the interactive system that exists between the living and nonliving components of an environment. From 1903 to 1907, Tansley had coordinated field studies that surveyed and mapped the types of vegetation found across the British Isles. As an educator, he strongly advocated fieldwork as being necessary to the education of any good ecologist. Observation Observation is the act of carefully watching something over time. Such observations may occur over short or long periods of time. Long-term studies are a key part of a scientist’s toolkit because most environmental changes happen over a long period of time. For example, studies of prairie-dog populations are helping scientists to determine which locations are most appropriate for the reintroduction of the black-footed ferret. The black-footed ferret is an endangered species that relies on the prairie dog as its main food source. One way that scientists monitor and observe populations is by conducting surveys. Visual surveys may be direct or indirect. Direct surveys are used for species that are easy to follow. In these surveys, scientists watch animals either with the naked eye or with tools such as binoculars or scopes. Indirect surveys are used for species that are difficult to track. In these surveys, scientists search for other signs of its presence, such as feces or a recent kill. FIGURE 1.3 Much of the data gathered by ecologists results from long hours of observation in the field. This ecologist is using radio telemetry to track gray wolves. Take It Further Prairie dogs are not only an important food source for the black-footed ferret but also a critical part of the prairie ecosystem. Prairie ecosystems that have healthy prairie-dog populations support a greater number of animals overall and have greater species diversity than prairies without them. Ask, In what ways, other than as a food source, might prairie dogs support other species? Their burrows provide shelter for other animals. In digging burrows, prairie dogs increase the nitrogen content in the soil and open up more area for oxygen and water absorption, all of which aid plant growth. Radio telemetry is another method used by scientists to monitor populations. Scientists fit an animal with a radio collar that emits a signal and then use the signal to track the animal’s movement, as shown in FIGURE 1.3. This practice is especially useful when studying a species that has a broad range, such as the gray wolf. A Apply How might a scientist use observation to study a population of mountain goats? Explain your answer. Answers A Apply A scientist might directly survey mountain goats by using binoculars or might indirectly survey them by looking for signs of feces (commonly called scat). A scientist could also use radio telemetry to track the goats. 390 Unit 5: Ecology Jim West/Alamy Ltd To monitor plant populations, scientists use a method called quadrat sampling. In this method, quadrats, or rectangular frames, are randomly placed on the study site. To determine plant population numbers, scientists identify and count the number of plants within each randomly selected plot. The total number of counted plants is then plugged into a mathematical formula to determine the plant population of the entire study site. Jim West/Alamy Ltd In addition to observing the activities of a species, scientists often determine the species’ population size. Rather than count every individual organism in a large study area, scientists can sample the population instead. Mark-recapture is a method used by scientists to estimate the population size of mobile organisms. For example, to monitor prairie-dog populations, scientists capture and mark prairie dogs with ear tags and then release them back into the wild. When scientists later repeat the survey, the captured prairie dogs will include both marked and unmarked animals. Scientists calculate the ratio of marked to unmarked animals and use this value to estimate the total population size. Differentiated Instruction Unit 5: Ecology 390 PRE-AP TEACH WITH TECHNOLOGY Have students use a graphic organizer to compare the advantages and disadvantages of direct animal surveys with those of indirect surveys. To get students started, have them consider these questions: How invasive is the technique to the animal? How easy is it to identify individuals? Is there the possibility of counting individuals more than once? How might weather conditions affect observations? Using a mapping database such as Google Earth or NASA’s Visible Earth, print out images of natural areas in your vicinity. Ask students to identify ecosystems from these images. Have students suggest strategies for mapping the vegetation in an area. BI CTXESE765030 C13S1.indd 390 Teacher Toolkit, Section C, T-Chart 07/07/15 4:39 P

CorrectionKey AL-A CorrectionKey AL-A QUICKLAB SA M PL I N G QUICKLAB Time 15 minutes Quadrat Sampling Ecologists often use quadrats—square or rectangular grids—to collect data about population numbers in an ecosystem. In this lab, you will use a quadrat to collect accurate and precise data on three “species.” Purpose Estimate population sizes by quadrat sampling. PROBLEM What is the population size of each species? PROCEDURE 1. Obtain a quadrat frame. Measure, calculate, and record the area of the quadrat. 2. Stand at the edge of the area you will sample and randomly throw your quadrat. 3. Move your quadrat so that it does not overlap with any other quadrat. Each different object represents a different species. Count how many individuals of each species are in your quadrat and record your data in a data table. Repeat this procedure three times. 4. Combine your data with that of your classmates. Find the average number of each species for all of the samples. Obtain the area of the sampling plot from your teacher. Calculate how many quadrats would fit in the area of the sampling plot. Multiply this by the average number of each species found in one quadrat to estimate the population of each species. LAB MANAGEMENT MATERIALS Conduct the lab indoors using common objects, such as paper clips, pencils, and erasers, placed randomly in a location whose area you have measured ahead of time. Count and record the objects before distributing them. Have students count any object within or touched by the quadrat. It is possible a very small population might not be sampled, depending on the placement of the quadrats. quadrat meter stick calculator objects to count ANALYZE AND CONCLUDE 1. Analyze Compare your population estimate for each species to the actual number that your teacher provides. Is the estimate accurate? Why or why not? 2. Evaluate How can you ensure that your estimate of population size will be as accurate as possible? Safety Avoid quadrats made from wire hangers. Teacher Note “I used to make quadrats out of hangers and had a couple of accidents with overzealous students. Surprisingly, a Hula-Hoop is almost a perfect square meter.” Experimentation Scientists may perform experiments in the lab or in the field. There are benefits and drawbacks to each type of experiment. While a lab experiment gives the researcher more control, the artificial setting does not reflect the complex interactions that occur in nature. A field experiment, on the other hand, gives a more accurate picture of how organisms interact in a natural setting. However, in a field study, it is more difficult to determine cause and effect due to the large number of factors at work in nature. A lab experiment is conducted in a controlled, indoor environment. This isolation helps scientists to focus each experiment on a very specific part of an ecosystem, such as a single organism. For example, to find out how climate change affects the growth rates of plants, scientists can grow plants in a lab and adjust temperature settings. Working in a lab allows scientists to control variables in a way that would not be possible in the field. A field experiment is performed where the organisms live. Like lab experiments, field experiments also have controls and manipulated variables. For example, to determine how browsing by deer affects plant and small-animal communities, scientists might fence off large study plots to keep out the deer. By monitoring the fenced and unfenced plots over a period of time, scientists can determine whether deer significantly change the areas in which they browse for food. CONNECT TO SCIENTIFIC METHOD As you learned in the chapter Biology in the 21st Century, all fields of science, including ecology, use scientific methods to investigate and answer scientific questions. Applied ecology uses the principles of ecology along with scientific methods to solve environmental problems. Answers Analyze and Conclude 1. Accept all reasonable answers. If the estimate is inaccurate, it could be because of inaccurate counting, miscalculation of averages, nonrandom sampling, or nonrandom distribution of species in a population. 2. Sample answer: Increase the number of samples taken, be sure quadrat size is appropriate for the size of the area sampled, obtain random samples, count accurately, and calculate averages accurately. A Contrast What is the difference between a lab experiment and a field experiment? Chapter 13: Principles of Ecology 391 BELOW LEVEL PRE-AP To illustrate the importance of a random sample, draw a square on a sheet of acetate and scatter paper dots across the square. Use a second sheet of acetate to cover the dots. Place on an overhead projector. With a small cardboard quadrat, show how different placements of the quadrat can affect the estimate. Discuss what would happen to the estimate if the quadrat were placed only where there were lots of dots to count. Ask, What is it called if a person’s own preferences influence a choice? bias Calculations of population density will be 07/07/15 covered in Interactions in Ecosystems. Ask, Knowing the size of a population for a given area, how could you predict the size of a population for a similar but much larger area? Calculate the average number of individuals per unit of area and apply to the larger area. PM BI CTXESE765030 C13S1.indd 391 4:39 PM Answers A Contrast A lab experiment is conducted in the controlled setting of a laboratory; a field experiment is conducted in a less controlled natural setting. Chapter 13: Principles of Ecology 391

CorrectionKey AL-A Modeling . Teach continued TEACH FROM VISUALS FIGURE 1.4 Discuss the challenges involved in developing and deploying transmitters on wild animals. Ask, What concerns must scientists address in developing transmitters to be placed on animals in their natural environments? safety in placing the unit; remote control of the unit; battery life; adequate storage space for data; size of unit (small, lightweight); durability; ability to access data without disturbing the animal; data retention if animal moves out of study area GPS transmitter FIGURE 1.4 Ecologists use data transmitted by GPS receivers worn by elephants to develop computer models of the animals’ movements. Answers A Evaluate How is modeling limited in representing ecosystems and the organisms . Assess and Reteach within them? Assess Use the Section Self-Check or Section Quiz, both available at HMDScience.com. Reteach Project on the board the image of FIGURE 1.2 from the Media Gallery. Have students take turns writing the types of research methods that would be appropriate at each level of the ecosystem. Have students explain their choices. SELF-CHECK Online 13.1 REVIEWING MAIN IDEAS 1. What are the five different levels of organization studied by ecologists? 2. Describe the three general methods used by ecologists to study organisms. 392 Unit 5: Ecology HMDScience.com Formative Assessment GO ONLINE CRITICAL THINKING 3. Apply What ecological research methods would you use to study bird migration? Explain your choices. 4. Apply How might an ecologist use modeling to study fire in a forest ecosystem? What are the limitations of such a model? CONNECT TO EVOLUTION 5. Ernst Haeckel was greatly influenced by the writings of Charles Darwin. How do the principles of ecology relate to understanding how adaptations occur? Unit 5: Ecology 1. organism, population, community, ecosystheir movement; experimentation—devise an tem, biome experiment to test what triggers migration; BI CTXESE765030 C13S1.indd 392 modeling—develop a computer model that 2. Observation is the act of watching someincludes different variables that might predict thing over time, such as a population of the time and path of migration birds; experimentation can occur in the lab or in the field and involves testing a hypoth- 4. Sample answer: Ecologists could use esis; modeling is a computer-based or models to determine movement of fire, math-based method used to predict how locations where prescribed burns should changes in one variable may affect another. take place, and areas with the potential for fire outbreaks. Limitations might include 3. observation—band birds and capture them at forest density, types of trees, plant and each end of their migratory route to record 392 Reuters/Corbis The combination of these data together with computer-generated maps creates a virtual ecosystem that scientists can use to model how one variable affects another. This type of modeling program sometimes plays a role in the development of wildlife conservation plans. Computer programs modeled population dynamics with and without the presence of the gray wolf. These programs were used to study how the reintroduction of gray wolves into Yellowstone might affect other species within the park and the surrounding area. By understanding how different organisms and factors within an ecosystem interact, wildlife managers are able to make well-informed decisions. A Evaluate Modeling is computerbased or math-based and relies on large amounts of data to make predictions. Experimentation involves the direct study of organisms, either in the lab or in the field. 13.1 FORMATIVE ASSESSMENT Sometimes the questions scientists wish to ask cannot be easily answered through observation or experimentation. Instead, scientists use computer and mathematical models to describe and model nature. Scientists can manipulate different model variables to learn about organisms or whole ecosystems in ways that would not be possible in a natural setting. Although they are used to test hypothetical situations, models are created with the use of real data. For example, in Kenya, scientists are using satellite technology to track the movement of elephants, as shown in FIGURE 1.4. These data, in turn, can be used to create a model to study how changes to the ecosystem might affect elephant movement patterns. Before putting the model to use, scientists can test it by inserting actual data values. Such testing allows scientists to make sure that the values predicted by the model are similar to actual observations in the field. In the United States, scientists developed a computer software program to create a virtual model of the Greater Yellowstone ecosystem. A variety of data were used to create this model, including the movements of elk, bison, bear, and wolf populations the location of different vegetation, such as meadows and forests the amount of snow the activities of geysers and other geothermal landforms animal populations, wind patterns, and weather conditions. 5. Species are adapted to their environments. This concept is directly related to the study of ecology, in which the interactions between organisms and the environment are studied. By understanding the interactions within an ecosystem, scientists can develop an understanding of how populations evolve in response to their environments. 07/07/15 4:39 P

Ecologists study relationships within each level of organization and also between levels. For example, researchers may study the relationships within . books, and write answers to the questions. Teacher Toolkit, Section C, Questions to Guide Reading BELOW LEVEL . SECTION 13.1 DO NOT EDIT--Changes must be made through "File info" .