This Document Contains Chapters 37 to 40 CHAPTER 37: BEHAVIORAL BIOLOGY WHERE DOES IT ALL FIT IN? Chapter 37 builds on the foundations of Chapter 27 and provides detailed information about animal form and function Students should be encouraged to recall the principles of animal classification and comparative anatomy. The information in chapter 37 does not stand. It connects the information on animal diversity to evolution and ecology coverage alone and fits in with the all of the chapters on animals. Students should know that animals and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth SYNOPSIS Animal behavior is the manner in which an animal responds to a stimulus from its environment. Behavioral biology studies how animals and their offspring survive and reproduce. These behaviors depend on a complex nervous system with sensory organs, an associative center, and a network of conducting fibers. Proximate causation explains how behavior works and can be studied by measuring physiological events. Ultimate causation explains why behavior evolved and can be studied by measuring the influence of the behavior on survival and/or reproduction. Ethology is an area of biology that examines the natural history of behaviors. Experimental evidence supports the involvement of genetics and sensory perception of the environment (neurology) in animal behavior. Behaviorists have long been challenged by the nature versus nurture controversy. These two extremes are not mutually exclusive, but work together to influence behavior. Learned behaviors are altered by experience and only somewhat related to an animal’s genetic background. The simplest type of learning, called nonassociative learning does not require a connection between stimulus and response as do associative behaviors. Habituation and sensitization are opposing forms of simple nonassociative learning. The two major types of associative learning are classical and operant conditioning. Certain other behaviors, called instincts, are strongly influenced by heredity and highly programmed. One type of parent-offspring interactions that occurs very early in the offspring’s life is called imprinting. Imprinting must happen during a specific time period called the critical phase. Another type of imprinting, called sexual imprinting, involves an individual’s recognition of potential mates within its own species. Overall, behavior is not limited by heredity, but provides a fundamental element that is then influenced by the interactions with the environment. Animal cognition, an exciting area of behavioral biology, which has called polarity amongst biologists, explores the question—“Can/do animals think?” Another area of study involves animal movements within the environment from place to place and returning. For example, orientation, the act of finding “home” when retuning from a foraging trip requires that the animal tract environmental “clues,” which enable that animal to return to the starting point, i.e., home. Migration involves navigation, adjusting or setting a course of travel and following that course. Communication is another important animal behavior. Animals communicate via several sensory channels including chemical signals (pheromones), taste, smell, touch, electricity, vision, and sound. Courtship behaviors are forms of communication readily studied in many animal species. These actions are nearly always species specific, which enhances reproductive isolation. Social groups ranging from insects to mammals, use various modes to communicate “local conditions.” For example, worker honey bees use a special dance to “explain” where a particular rich patch of nectar is located. Prairie dogs alert their colony members of approaching dangers. Vocal communication is most pronounced in humans, which may reflect a certain genetic ability to manage abstract information. Virtually all languages draw from the same set of consonant sounds. The ability to learn language is genetically programmed and decreases with age. Behavioral ecologists study how natural selection shapes behaviors to increase an animal’s overall fitness. Foraging behaviors are associated with the selection, collection, and processing of food items, a necessary behavior for heterotrophs. Animals that are foraging specialists feed on only a few types of organisms, while those that are generalists feed on many kinds. Optimal foraging theory attempts to explain how evolution favors foraging efficiency. Territoriality is closely related to foraging for food, acquisition of shelter, and reproduction and has adaptively important consequences. When resources are limited, territoriality helps to ration those resources. Mating and reproductive behaviors are among the most complex behaviors. These actions help ensure that the expenditure of gametes and reproductive energy will result in viable offspring. Reproductive behavior also extends to rearing of the young. Mate choice is directly related to the overall expenditure each parent in a species makes in raising the offspring. Parents with the greatest investment should be the ones that make the mate selection. Mate choice is a process of sexual selection frequently based on secondary sexual characteristics and dependent on reproductive competition. In intrasexual selection, individuals of one sex (usually males) compete. Only a few males do most of the breeding; the rest do not breed at all. Sometimes the competition is not directly between two males but between their sperm, called sperm competition. The three most common types of mating systems are monogamy, polygyny, and polyandry. Recent quantification of paternity through DNA fingerprinting shows that there is substantial “cheating” in the bird world. Other species have evolved unusual mating tactics where unobtrusive males sneak in undetected to breed with females and continue their genetic linage. Animal behavior also includes an unusual activity called altruism where the activity of an individual may benefit the group at the expense (possibility its life) of the individual. Such behaviors contradict evolution unless one considers the concepts of inclusive fitness and kin selection. One can maximize inclusive fitness by sacrificing one’s self for one’s relatives. Most animals opt for reciprocal altruism, the proverbial “I’ll scratch your back, if you scratch mine.” The best strategy to optimize the transmission of one’s own genes may be to cheat and selfishly get others to sacrifice themselves and then not return the favor. This rarely occurs in nature when the altruistic act is inexpensive because the gain to the cheater is not worth the future lack of reciprocation. Two of the most studied vertebrate altruistic acts are cooperative breeding and alarm calling. The former sets up a family-like structure in which young, non-reproductive, but related, individuals assist a breeding pair in raising their young. In alarm calling, sentries are willing to draw attention to themselves by calling out to alert others of the presence of a predator. Alarm calls by an individual are more likely if the caller and its neighbors are related. Eusocial insect societies are complex and exhibit altruistic activity in defense and reproduction within the colony. The high degree of genetic relatedness in a colony may be one of the reasons for such extensive altruism. Most insects possess the haplodiploidy system of sex determination. Males are haploid, females are diploid, and the female workers share nearly 75% of their genes. Altruism allows workers to maximize inclusive fitness. Vertebrate societies are neither as complex nor as altruistic as eusocial insect societies. The individuals in vertebrate societies also share significantly less genetic heritage. Naked mole rats are unusual mammals that organized into societies very much like eusocial insects. They have functional and reproductive division of labor, workers of both sexes perform various tasks according to body size, and a single female is responsible for all breeding. LEARNING OUTCOMES 37.1 An Animal’s Genome Influences Its Behavior 1. Discuss the types of studies that have provided evidence to link genes and behavior. 37.2 Learning Also Influences Behavior 1. Discuss the role of the critical period in imprinting. 2. Explain the importance of identical twins to studies of behavior. 37.3 Thinking Directs the Behavior of Many Animals 1. Provide evidence for claims that nonhuman animals can think. 37.4 Migratory Behavior Is Both Innate and Learned 1. Describe migration using a real-world example. 2. Distinguish between orientation and navigation. 37.5 Animal Communication Plays a Key Role in Ecological and Social Behavior 1. Explain the role of courtship signals in reproductive isolation. 2. Describe how honeybees communicate information on the location of food sources. 37.6 Natural Selection Shapes Behavior 1. Describe behavioral ecology. 2. Discuss the cost-benefit analysis of feeding behaviors. 3. Explain the evolutionary benefit of territorial behavior. 37.7 Behavioral Strategies Have Evolved to Maximize Reproductive Success 1. Explain parental investment and the prediction it makes about mate choice. 2. Describe how sexual selection affects the evolution of secondary sexual characteristics. 3. Explain why some species are generally monogamous and others are polygnous 37.8 Some Behaviors Decrease Fitness to Benefit Other Individuals 1. Explain altruism and its potential benefits. 2. Explain kin selection and inclusive fitness. 37.9 Group Living Has Evolved in Both Insects and Vertebrates 1. Explain the possible advantages of group living. 2. Contrast the natures of vertebrate and insect societies. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 37 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students believe higher animals lost their instincts • Students believe that instincts cannot be modified • Students believe all complex behavior is learned • Students believe artificial selection produces new traits • Students are unaware that mutations can lead to behavioral changes • Students are unaware of evolution at the population level • Student think that selection is directional and produces superior characteristics • Students are unaware that mate selection drives population genetics • Students do not believe that random genetic drift produces population differences • Students think that all animals evolved at about the same time • Students believe that most animals are vertebrates • Students do not equate humans with being animals • Students believe that all animals have identical organ system structures INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE One can have fun with communication via other senses. It is most readily done via body language. Often it is more important how something is said than what is said. This has become more pronounced with the reliance on television as the only source of news. A lie is more readily believed if said straight faced and serious than the truth told in a wavering, hesitant voice. Try telling your students they performed “average” in a harsh voice versus an enthusiastic one. Then determine what they presume the “average” score was in each case. Tell them to go home and tell their dog that it was bad in a gleeful manner. Most animals will respond positively to the tone, but will not recognize the word “bad.” Researchers in Scotland have reported that dolphins greet each other by “name” using distinctive signature whistles. Discuss animal awareness and the recent push for animal rights, using animals in experiments that benefit humans, and so forth. Humans share the planet with all animals and plants, but do we have the right to rule over them? And if we do, how far can we morally and humanely go? After all, biologically we are animals, too! This may help put things in a more balanced perspective. Observe social behavior within the classroom. Have the students identify their home range and discuss whether or not they defend their territory. If so, why do they feel this is true? And if not, why is it not true? Discuss altruism and reciprocal altruism in terms of class activities like taking notes and studying for exams. When is it worthwhile for a student to allow another student to copy his/her notes? Is it more valuable to study with others or keep one’s knowledge to one’s self? Discuss mate choice with regard to human societies. Discuss altruism and reciprocal altruism in terms of environmental, economic, and health problems. To what degree should we allow another country to destroy its forests if down the road it affects our climate as well? How charitable are contributions when they are primarily made as a tax break? What are the long term consequences of helping individuals with genetic deficiencies survive? HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 37. Application • Have students explain the effects of mutations on genes associated with bird songs. • Have students explain how resources in a territory affect a male animal’s reproductive success. • Ask students explain the selective factors that lead to sexual dimorphism in animal behaviors. Analysis • Have students assess evidence that rats can be selected for intelligence. • Have student explain why human development disrupts mating behavior of territorial animals. • Ask students compare the social structure of insect colonies to a human population in a city. Synthesis • Ask students to design an experiment that determines whether bees use landmarks as a way of remembering the locations of previously visited flowers. • Have students come up with an application of the knowledge that parent–offspring interactions can influence cognition. • Ask the students come up with strategy to test whether birds of the same species have regional dialects just like humans. Evaluation • Ask students evaluate accuracy of using social insects as a model for human behavior. • Ask students to access the ethics of using primates to study the effects of environmental stress on human mental disorders. • Ask students investigate the claims that human, just like rats, can be selected for intelligence by mate selection strategies. VISUAL RESOURCES Obtain photos of various animal postures indicating specific behaviors. Compare the facial expressions of various primates to those of humans. Try and interpret the faces with human emotions—happy, sad, hurt, sleepy, anxious, etc. The ultimate in entertainment and avian imprinting—rent the movie “Fly Away Home.” Obtain photos of examples of animals (primarily males) that exemplify reproductive competition and sexual selection. IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Fetal Development Timelines Introduction This demonstration uses instructor-controlled animations to help students understand mate selection strategies that affect population behaviors. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to University of Arizona Animal Behavior website at http://eebweb.arizona.edu/Animal_behavior/chase/runaway_slides.htm Procedure & Inquiry 1. Tell the class they will be viewing animations about mate selection. 2. Load up the University of Arizona Animal Behavior website and ask students to observe the male and female populations 3. Click on the “Forward” button and go through the sequence 4. Have students describe the changes occurring in each population 5. Then have the students explain how this sequence of events applies to population behaviors LABORATORY IDEAS A. Isopod Issues This activity has students design an experiment to investigate behavioral adaptation preferences for certain environments. a. Explain that they will be designing an experiment to investigate behavioral preference adaptations for certain environments. b. Provide the students with the following: a. Terrestrial isopods or pill bugs b. Soil Variables i. Soil from area ii. Dark potting mix iii. Sand iv. Peat moss v. Perlite c. Plastic food containers d. Various fruits and vegetables i. Carrots ii. Potatoes iii. Broccoli iv. Corn v. Celery vi. Beans e. Aluminum foil f. Light source g. Thermometers h. Rocks i. Incubators or temperature controlled environments. j. Ask the students to design experiments to investigate the isopod’s responses to different environmental conditions. They must first investigate the natural living conditions of terrestrial isopods and then design a method of testing preferences for certain environmental conditions c. They should be asked to look at behavioral adaptations in relationship to factors such as: a. Food availability b. Shelter c. Soil type d. Moisture e. Lighting conditions f. Temperature d. Students should be asked to keep field notes about any behavioral preferences compared to their natural conditions. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students volunteer at a nature center. 2. Have students tutor high school students studying animals. 3. Have student produce an annotated list of readings on animal behavior for a local library. 4. Have students do a public forum on sociobiology in everyday society. CHAPTER 38: ECOLOGY OF INDIVIDUALS AND POPULATIONS WHERE DOES IT ALL FIT IN? Chapter 38 builds on the foundations of biodiversity and provides detailed information about environmental interactions of organisms. Students should be encouraged to recall the principles of organismic classification and comparative anatomy. The information in chapter 38 does not stand alone. It connects the information on organismic diversity to evolution and ecology coverage. Students should know that animals and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. SYNOPSIS Ecology is the study of complex and interwoven relationships of organisms with one another and their environment. Several environmental elements directly affect individuals and thus a population’s distributional patterns on Earth. Organisms are grouped in progressively larger levels of organization: communities, ecosystems, and biomes. A population of organisms comprises individuals of a given species that occurs in one area at one time. It has characteristic features including range, dispersion, and size. No populations can exist in all locations, nor do population ranges remain constant. Population ranges expand and contract as the environment changes. Individuals in populations are arranged in one of three kinds of spacings. Clumped spacing is most common in nature, although randomly and uniform spaced populations also exist. Clumped distributions tend to form as a result of individuals clustering in microhabitats, which themselves are not generally uniformly distributed. Metapopulations are networks of distinct, interacting populations. The interactions result from the exchange of individuals between populations. Populations in better habitats within an area are called sources, while those in poorer areas are called sinks. Sink populations can often go extinct if not regularly resupplied with individuals from source populations. Demography is the statistical study of populations. Numerous factors affect population growth rates including sex ratio, generation time and an age structure. Life tables, which depict a particular cohort’s age and survivorship at a specific age, are used to assess how natural populations change over time. Populations exhibit the typical survivorship curves that indicate the percentage of the original population that survives to a given age. Type I have low mortality while young and high mortality in post reproductive years. Individuals in type II populations are equally likely to die at any age. Type III produce many offspring that are likely to die very early, with established adult individuals who have low mortality. An organism’s complete life cycle is called its life history. Life histories are very diverse and wholly dependent on each organism. They often reflect trade-offs between reproduction, growth, and survival. Natural selection favors maximizing lifetime reproductive success. When there is a low cost of reproduction, as when resources are abundant, many offspring should be produced. When there is a high cost of reproduction, for example when reproduction affects survival of the parents or their future reproduction, fewer offspring should be produced. The number of offspring produced is overall less important than that offspring’s ability to reproduce. All healthy populations have the capacity to grow, although over time most populations remain relatively constant regardless of the number of offspring produced. The intrinsic rate of increase is the population’s biotic potential expressed by the equation dN/dt = riN. Overall the rate of change over time is equal to the intrinsic rate of growth of that population multiplied by the number of individuals in that population. The normal innate capacity for population growth is exponential. The carrying capacity of a population is its characteristic limit imposed by environmental shortages. This capacity is a dynamic value that varies over time, fluctuating around a mean population value. Graphing population growth over time generally produces a sigmoid curve where the rate of increase declines as the population numbers increase. Population growth is also affected by density-dependent and density-independent processes. The former include size of the population, predators, behavioral changes, and emigration. The latter include factors like weather and the physical disruption of the habitat, such as fires and floods. Populations may exhibit regular, repeated cyclic patterns. The most common example is that of the snowshoe hare. Increased numbers of prey result in increased predator numbers. This decreases the prey population and leads to a decrease in number of predators. The prey population is additionally affected by the amount of its own food source. Populations are characterized as either r- or K- life history selected adaptations. r- selected populations exhibit exponential growth with sudden crashes and have a high intrinsic rate of growth (r). They reproduce early, have many offspring in a large brood. The offspring are generally small, mature rapidly, and receive little parental care. K selected adaptation populations exhibit sigmoid growth curves limited by carrying capacity (K). They reproduce later in life and have small broods. Their offspring are generally large, mature more slowly, and receive more intensive parental care. Human populations continue to grow exponentially as humans have expanded the carrying capacity of their habitats—often at the expense of other living organisms. Although some countries, Ethiopia for example, have reached or exceeded their K, the Earth as a whole has not, causing an uncertain future. Several countries’ ecological footprints foreshadow hard times ahead for our planet. LEARNING OUTCOMES 38.1 Populations Are Groups of Single Species in One Place 1. Explain how a species’ geographic range can change through time. 2. Describe how individuals of a population may be distributed in space. 3. Distinguish between a population and a metapopulation. 38.2 Population Growth Depends upon Members’ Age and Sex 1. Define demography. 2. Describe the factors that influence a species’ demography. 38.3 Evolution Favors Life Histories That Maximize Lifetime Reproductive Success 1. Illustrate how an organism’s life history is affected by reproductive trade-offs. 2. Compare the costs and benefits of allocating resources to reproduction. 38.4 Environment Limits Population Growth 1. Describe exponential growth mathematically. 2. Explain how carrying capacity affects the exponential growth curve. 38.5 Resource Availability Regulates Population Growth 1. Compare density-dependent and density-independent factors affecting population growth. 2. Describe how density-independent factors limit population growth. 3. Evaluate the reasons why some populations cycle in size. 4. Distinguish between K-selected and r-selected populations. 38.6 Earth’s Human Population Is Growing Explosively 1. Describe how the rate of human population growth has changed over time. 2. Describe the effects of age distribution on future growth. 3. Describe a typical American ecological footprint. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 38 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students are unaware of metapopulation effects • Students believe that predator-prey population fluctuations are uniform over time • Students do not account that predators seek many types of prey when looking at population fluctuations • Students do not account that prey are taken by several types of predators when looking at population fluctuations • Students believe that population behavior is not subject to selection • Students believe artificial selection produces new traits • Students are unaware of evolution at the population level • Student think that selection is directional and produces superior characteristics • Students are unaware that mate selection drives population genetics • Students do not believe that random genetic drift produces population differences • Students think that all animals and plants evolved at about the same time • Students believe that most animals are vertebrates • Students believe that most plants are angiosperms • Students do not equate humans with being animals INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE The cost of reproduction can be compared to spending money now versus saving for the future. If you buy that car now, yes, you will have it to drive around and be cool, but if you drive it too much you wear out the tires, and you won’t have any money to buy new ones (you die). If you wait and save your money it will gather interest, then you buy the car, drive it and the interest you gained will provide the funds to buy new tires. Source-sink metapopulations are like a socialistic society (or Robin Hood). Take from the rich and give to the poor. Discuss the human population explosion and how it can be examined with density-independent and dependent models. We too frequently think just in terms of producing enough food for the populace without considering the demands on other resources and accumulation of toxic and natural wastes. The egg size versus clutch size problem is similar to what is found in many erythropoietic diseases/difficulties. If fewer red blood cells are produced by the stem cells, they are usually larger in size or contain more iron so that sufficient oxygen transport can still occur. This may not occur if hemoglobin precursors are limited. Clearly differentiate between the kind of growth that occurs when there are no environmentally limiting factors (exponential growth) and that which occurs when limitations do exist (sigmoid growth). The two types of growth curves also relate to whether an organism is an r strategist (exponential growth) or a K strategist (sigmoid growth). Discuss why it is more likely for a K strategist to become extinct than an r strategist. Discuss the human population explosion. Common sense indicates that we should want to kill infected rats to prevent the spread of bubonic plague. New population dynamic models indicate though, that doing so may actually make an outbreak worse. If the rats are killed, the fleas will find other mammals to feed on. Fleas also live on mice, squirrels, chipmunks, prairie dogs, and humans. Human plague outbreaks occur when rodent populations are low, forcing the hungry fleas to seek blood from other sources. Killing more rodents would only increase the fleas’ need to find new hosts. HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 38. Application • Have students explain the probable spacing of cave dwelling fish in a coral reef. • Have students explain the value of high genetic variation is the adaptive survival of a population. • Ask students how inbreeding could influence the survival of a population in an unchanging environment. Analysis • Have students explain if human diversity could have due to genetic drift. • Have student describe how deforestation affects the ratio of herbivores to carnivores in an area. • Ask students to explain the reproductive strategy of a lizard that only has female members in its population. Synthesis • Ask students to design an experiment to test if weeds are more successful as r-strategists or K-strategists. • Have students design an experiment to test the effects of global warming on fish populations in small ponds. • Ask students to come up with an application of age structure studies in various human populations. Evaluation • Ask students to assess the pros and cons of mandatory human zero population growth programs in a county. • Ask students to access the accuracy of using animal models of resource usage to understand human populations. • Ask students investigate the pros and cons of protecting agricultural animals from potentially fatal infectious diseases. VISUAL RESOURCES Show simple interspecific competition between two microorganisms in a petri dish. Fungi “wars” can be quite impressive. Inoculate a series of plates over a period of time to show the progress of each organism. Many microorganisms produce antibiotics to kill off other microorganisms and out-compete them in the same habitat. Have students conduct a 24 hour “garbage survey” of what they throw away in one day. They should keep a log and submit to a collector who will collate the results. If the data are presented graphically they will lead to good in-class discussions about the “throw away” society and the ecological footprint that the United States places on the Earth. Have groups of students construct a simple life table using different mortality rates and presents to the class on an overhead projector. Show photographs of different organisms (plant, animals, and fungi) and let students respond to which survivorship curve best fits (I, II, III). Show photographs of different organisms (plants, animals, and fungi) and let students respond to which is an r-strategist and which is a K-strategist. IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Guess the Hotspot Introduction This demonstration has the instructor lead students through the rationale that biologists use to define biodiversity loss hotspots. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to Biodiversity Hotspots website at http://www.biodiversityhotspots.org/xp/Hotspots Procedure & Inquiry 1. Tell the class they will be viewing different locations around the world defined as biodiversity decline hotspots. 2. Load up the Biodiversity Hotspots website and click on the Interactive Map 3. Ask the class to describe the locations of the hotspots on the map 4. Then pass the cursor over each hotspot for its environmental description 5. Ask the students why certain areas are declining in biodiversity 6. Click select hotspots for more information and discuss the human factors leading to biodiversity loss in different regions of the world. 7. Have students briefly describe probable biodiversity changes in your area LABORATORY IDEAS A. “Squirrel” Population Dynamics This activity has students investigate a theoretical model for squirrel population dynamics. a. Explain that they will be using beans to represent population growth in a theoretical squirrel population. b. Provide the students with the following: a. Graph paper b. Two colors of dried beans c. Large polystyrene cups to hold beans - Squirrels d. Pennies – Predators e. Peanuts f. Fake bait worms c. Tell each student to take a bean of each color. d. Tell them that one bean is a male squirrel and one bean is a female squirrel and that they are going to record the squirrel population for ten years under conditions with no limiting factors. Squirrels produce one generation of offspring per year and are sexually mature after one year. e. Tell them that each pair of squirrels gives birth to four squirrels, two males and two females. f. Have the students collect beans to build new population as the ten years pass. Have the students get record the population numbers on the graph paper. g. Have students recognize the distinct characteristics of the squirrel population without limiting factors. h. Next have the students add the following limiting factors to another ten years: a. Predators – Kills two squirrels per predator per year. They should add a certain number of predators to look at the effects of predator population on the squirrel population. b. Food – One peanut feeds a squirrel. Add and subtract peanuts to look at the effects of food on the squirrel population. c. Parasites – One “worm” halves the reproductive rate of one squirrel pair. Add and subtract worms to look at the effects of food on the squirrel population. i. Have students describe how changes in limiting factors effected the population of the squirrels. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students volunteer at a nature center. 2. Have students tutor high school students studying ecology. 3. Have students do a presentation on biodiversity to elementary school students. 4. Have students volunteer with a conservation group on biodiversity preservation projects. CHAPTER 39: COMMUNITY ECOLOGY WHERE DOES IT ALL FIT IN? Chapter 39 builds on the foundations of biodiversity and provides detailed information about environmental interactions of organisms. Students should be encouraged to recall the principles of organismic classification and comparative anatomy. The information in chapter 39 does not stand alone. It connects the information on organismic diversity to evolution and ecology coverage. Students should know that animals and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. SYNOPSIS Moving toward increased complexity, biological communities follow populations. Biological communities, simply referred to as communities, are all of the species or organisms occurring in a particular area. Among the most complex concepts of populations is that of the niche. Niche is not synonymous with habitat as it includes behavioral, reproductive, and seasonal factors. The principle of competitive exclusion can be restated in terms of the niche; two species cannot occupy the same niche indefinitely. They can coexist while competing for the same resources, but at least one feature of their niches must differ or one will succeed and the other will go extinct. Interspecific competition limits population size when two kinds of organisms use the same resource, which is limited in supply. The principle of competitive exclusion states that when two species compete for the same limited resource, one will utilize the resource more efficiently which results in the elimination of the other. Continued competition between species rarely occurs. Either one or the other species is driven out or natural selection reduces the competition between them. Competition is also avoided through geographical partitioning. Although sympatric species live in the same area, they utilize different resources. Sometimes when niche overlap appears, the two species are able to partition the resource and thus coexist. Character displacement occurs when co-occurring species exhibit greater morphological differences and resource use. It is often hard to determine interspecific competition without constructing complex experiments. Even then, interpretations suggesting negative results do not always indicate competition. Detailed studies of ecological requirements often best explain interspecific interactions. Predators have major effects on prey populations. Predation limits population size and is an important form of biological control. It places selective pressure on prey often causing a co-evolutionary arms race with prey and predators constantly evolving strategies to defeat each other. Many plants produce physical structures or chemicals to discourage or prevent animals from herbivory activities. Such chemicals are called secondary compounds to differentiate them from primary chemicals involved in normal metabolic pathways. Some animals have been able to adapt secondary plant compounds for use in their own defense. The distastefulness of the monarch butterfly is perhaps the best known example. Its taste results from eating alkaloid-producing milkweed as a larva. Larvae that do not feed on these plants are quite tasty to birds. Animals develop defenses against predators, often by defensive coloration or chemical defenses. The monarch is an excellent example of aposematic coloration, bright warning coloration that tells predators to stay away. They advertise their toxicity to increase their survival. Cryptic coloration, on the other hand, allows an animal to blend in with its surrounding; its survival depends on hiding. The viceroy butterfly is a Batesian mimic that depends on its similarity to the toxic monarch for survival. Muellerian mimics are frequently unrelated, but protected, species that all look alike, providing a sort of group defense. Organisms evolve in a positive manner as well. An excellent example is the co-evolution that has occurred between flowering plants and their pollinators. Among the best known symbiotic relationships are those found in lichens, mycorrhizae, and legumes. If the one partner benefits with no change to the other, the relationship is commensalism. If both participants benefit, it is mutualism. If one benefits and the other is harmed, the relationship is parasitic. Gray areas exist among these relationships as it is often difficult to determine whether a partner truly benefits by the actions of the other. Both commensalism and mutualism can readily turn into parasitism if even the slightest, unintentional damage occurs to the non-benefiting partner. Parasites that eliminate their source of food, that is kill their host, are not successful since they cause their own demise as well. Organisms that cause lethal disease are similarly not successful. Both predation and parasitism may counter the effects of competition by influencing the outcome of interspecific interactions. The plants and animals that make up ecosystems change over time as the physical nature of the ecosystem changes. Secondary succession occurs in inhabited areas that are disturbed in some manner: Such disturbances are often initiated by humans. Primary succession occurs in areas made devoid of all life. It is readily seen on new volcanic islands, but also occurred millions of years ago when glaciers retreated from the northern hemisphere. Biodiversity, species richness, and species diversity promote community stability. Factors that promote species richness include ecosystem productivity, spatial heterogeneity, and climate. The tropics exhibit a greater number of species than any other biome. This may be due to the long evolutionary age of the tropics combined with high productivity, predictability of climate, intense predation, and spatial heterogeneity. A predictable species-area relationship has been observed as one of the most predictable patterns in ecology. The equilibrium model of island biogeography proposes that, in time, the number of species extinctions and colonizations balance each other out and the number of species remains constant. In addition, distance to sources (other islands or to a mainland) for colonizers and island size play important roles in supporting the colonization/extinction events that occur on islands. Islands should not just be though of as “somewhere” in the Pacific Ocean but also mountain tops and other isolated areas on the planet. Ecosystems follow biological communities in the increasingly complexity toward the biosphere. Ecosystems are the most complex level of organization because they include biotic and abiotic factors. The Earth is a closed system with respect to chemicals and nutrients, but an open system with regard to energy from the sun. All substances in organisms cycle through the ecosystem. These cycles may be short lived or may take thousands of years to go full circle. Many of these substances have atmospheric reservoirs while others are contained within soils and rocks. Rarely is the bulk of any substance contained within bodies of organisms. However, one must consider the tremendous amounts of stored nutrients (for example carbon, oxygen, nitrogen) that are stored in plant tissues in a forest or grassland. Among the more important biogeochemical cycles are those that involve water, carbon, nitrogen, and phosphorus. Life depends on water, 98% of which is found in oceans, in surface fresh water, and as ground water. Life also depends on carbon, most of which is contained in the carbon dioxide of the atmosphere. Various photo synthesizers fix carbon into organic substances which are then passed to various heterotrophs. Carbon is returned to the atmosphere via respiration and when an organism dies and decomposes. Until recently, the processes of photosynthesis and respiration/decomposition have roughly balanced each other. The burning of fossil fuels (coal, oil, natural gas) and the destruction of vast areas of photosynthesizing plants is tipping that scale in the direction of increased atmospheric carbon dioxide. Nitrogen gas comprises 78% of the atmosphere. It is only available to organisms by the action of various nitrogen-fixing bacteria. Leguminous plants harbor such bacteria, which are readily visible in their root nodules. They fix sufficient nitrogen for their own growth and release the excess into the soil, fertilizing it without the addition of costly chemicals. The phosphorus cycle is typical of many of the other mineral-oriented biogeochemical cycles. Much phosphorus is taken up by marine organisms which are then eaten by ocean birds. Guano is among the richest fertilizers available. Only a small percentage of the sun’s energy is captured by photo synthesizers; even less of this energy is passed on to animals. In terms of energy utilization, it is better to be a vegetarian or herbivore than a carnivore. Each successive level of consumer is a trophic level and includes photo synthesizers, primary consumers, secondary consumers, decomposers, and detrivores. Primary productivity is the total amount of organic matter produced from the sun’s energy within a given system. Some energy is lost in the metabolic activities of the initial photo synthesizers, resulting in the net primary productivity value. The weight of all of the organisms living in an ecosystem is the biomass of that ecosystem. This figure increases as a result of net productivity. Many ecosystems have both high productivity and high biomass. Others have high productivity but low biomass. Tropical forests and wetlands have the highest biomass ratios, while deserts have the lowest. Energy is passed through an ecosystem in a series of small steps comprising a food chain or a food web. In theory, higher productivity should support longer food chains, but in reality little energy remains after only four steps. The relationships of these trophic levels are diagrammatically represented by biomass and energy pyramids. Occasionally a biomass pyramid may be inverted, but the energy pyramid cannot be inverted. Trophic levels dramatically affect each other through a phenomenon called a trophic cascade. Lower trophic levels can influence higher levels via bottom-up effects. In addition lower and higher trophic levels can cancel each other out or reinforce each other, producing extremely complicated food web interactions. LEARNING OUTCOMES 39.1 Competition Shapes How Species Live Together in Communities 1. Define community. 2. Differentiate between fundamental and realized niches. 3. Describe how competitive exclusion operates. 4. Explain how niche overlap may lead to resource partitioning. 39.2 Predator–Prey Relationships Foster Coevolution 1. Describe the effects predation can have on a population. 2. Describe mechanisms plants use for defense against predators. 3. Describe mechanisms animals use for defense against predators. 4. Distinguish between Batesian and Müllerian mimicry. 39.3 Cooperation Among Species Can Lead to Coevolution 1. Explain the different forms of symbiosis. 2. Differentiate between commensal relationships and symbiotic ones. 3. Explain how mutualism leads to coevolution. 4. Explain how parasitism can affect community structure. 5. Explain how species interactions have both direct and indirect effects. 39.4 Ecological Succession Is a Consequence of Habitat Alteration 1. Distinguish between primary and secondary succession. 39.5 Chemical Elements Move through Ecosystems In Biogeochemical Cycles 1. Explain the importance of element cycling within Earth’s ecosystems. 2. Describe the basic carbon cycle. 3. Describe the basic water cycle. 4. Explain how microbial activities drive the nitrogen cycle. 5. Compare the cycling of phosphorus to the cycling of other key elements. 39.6 Energy Flows Through Ecosystems in One Direction 1. Relate the First and Second Laws of Thermodynamics to the biosphere. 2. Describe the different trophic levels of ecosystems. 3. Explain how energy moves through trophic levels. 4. Compare standard and inverted biomass pyramids. 39.7 Biodiversity May Increase Ecosystem Stability 1. Define ecosystem stability. 2. Describe the effects of species richness on ecosystem function. 3. Illustrate how multiple factors affect species richness in the trophics. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 39 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students oversimplify intraspecific competition effects • Students oversimplify interspecific competition effects • Students are unaware of the complexity of organismic interactions • Students believe that predator-prey population fluctuations are uniform over time • Students do not account that predators seek many types prey when looking at population fluctuations • Students do not account that prey are taken by several types of predators when looking at population fluctuations • Students believe that population behavior is not subject to selection • Students believe artificial selection produces new traits • Students are unaware of evolution at the population level • Student think that selection is directional and produces superior characteristics • Students are unaware that mate selection drives population genetics • Students do not believe that random genetic drift produces population differences • Students think that all animals and plants evolved at about the same time • Students believe that most animals are vertebrates • Students believe that most plants are angiosperms INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE Many students may not realize that a vast majority of medicinal compounds were initially extracted from plants, i.e., aspirin from willow bark, digitalis from foxglove plants, and leukemia treatment from the periwinkle plant. Humans have used secondary plant compounds to their benefit as have other animals. Traditional medicine of the Appalachian peoples and of China is being studied to determine the active ingredients behind the many beneficial folk treatments. These compounds may be isolated and synthesized commercially. Unfortunately many traditional remedies fail, not because they are inherently bad, but because the plant chemicals are not always produced, or are not produced in uniform amounts. A great amount of variation is dependent on seasonal temperature and rainfall as well as natural soil conditions. Many insects have evolved unique behaviors to cope with the stimulated production of plant chemicals. Some nip the midrib to keep them from entering the leaf they are eating; others chew circles on the leaves, eating only the inside. Recent research shows that plants communicate over great distances, presumably by airborne chemicals. Thus, a tree may begin to produce secondary compounds even though it is far removed from the actual herbivore attack. Tobacco plants, for example, produce salicylic acid (aspirin) to alert their immune system to fight an infection of TMV. Some of the acid is converted to methyl salicylate and evaporates from the damaged plants. When this air wafts over non-infected tobacco plants, the salicylate is absorbed and turned into salicylic acid. Many frogs in the Amazon are poisonous, though they possess absolutely no poisons on their skins when they are born. They only secrete the poisons as adults. Examination of the stomachs of these frogs revealed the presence of ants. The ants contain up to 20 different toxic alkaloids. The most dangerous of these frogs, Dendrobates auratus has a diet that is 70% toxic ants! Use hypothetical social examples to explain various forms of coloration and mimicry. One of the best ways to avoid being mugged is to act slightly crazy—similar to aposematic coloration. The use of camouflage in hunting is obvious. Another is to have students think about various traffic control signs (yellow-black, red-white, orange-black), which are colored distinctly to display warnings. There are increasing numbers of pan-handlers in most cities; as residents discover that many are actually making a decent living from such activity, they are less likely to give money to anyone—similar to Batesian mimicry. Another example of brood parasitism occurs in a species of mouth brooding catfish. Another species of fish (analogous to the catbird) presents its young near the catfish mother, who sucks them up as though they were her own young. Over time her true young and the intruders both grow and develop. Unfortunately, the catfish young provide an additional food source for the intruders who grow too much greater proportions. After the normal brooding period, the catfish mother releases her “young,” which turn out to be only a few individuals of the brood parasite species. She has expended substantial energy to raise another species and has no new generation of her own species! Have students discuss the consequences to removing a forested area and converting it to grassland. What animals will disappear and what new animals will colonize the new grass area. This should lead them in the direction of how different species of animals and their distributions are directly related to the types of vegetation in the area. HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 56. Application • Have students explain the impact of wild dogs on biodiversity in your area. • Have students describe how the dying off of one type of tree affects biodiversity of a forested area. • Ask students to explain one impact of introducing a non-native bird into an area where it competes for food with another species of bird. Analysis • Have students compare and contrast a parasite and a pathogen. • Have student describe the pros and cons of brood parasitism in birds. • Ask students to explain the evolutionary effect on a prey species when its major predator becomes extinct. Synthesis • Ask students to design an experiment to test if an invasive fish is competing for resources with native fish. • Have students design an experiment to test the origins of toxins produced by tropical frogs. • Ask the students come up with an agricultural application of a pathogenic virus that exclusively kills parasitic worms of animals. Evaluation • Ask students evaluate the use of non-native parasitic wasps to control populations of invasive moths that are devastating crops. • Ask students weight the environmental impacts of eradicating the disease rabies from local populations of wildlife. • Ask students investigate the pros and cons of introducing non-native organisms in an area to replace fill the role of a native one that died off. VISUAL RESOURCES Slides of various forms of mimicry are a necessity. One can include various poisonous animals, including rattlesnakes, and coral snakes and the others that mimic them (hognose snake and scarlet king snake respectively). Bring various colored photographs (for example, from entomology books) and discuss some of the common colors that appear between unrelated insects. This can also be done with botany books (photos of colored flowers) and then see if students can put together the idea of co-evolution between insect and the flowers that demand their attention by advertising with color and fragrance. The co-evolution of flowers and their pollinators is especially interesting and highly specialized. Among the most specific relationships are between wasps and tropical orchids. As a result of intense co-evolution, the extinction of one partner will likely result in the extinction of the other. This is especially true if the extinction is caused by humans and happens over a short time span. Under natural circumstances the second partner might have the time and opportunity to evolve less dependency on the first partner. The animated film “Antz” has a really cute part where the worker and soldier ants are in an ant “bar” and the worker ant (Woody Allen’s voice) refuses the glob of “honeydew” commenting it doesn’t drink stuff that comes out of another insect’s anus! IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Interspecific Interaction Role Modeling Introduction This demonstration involves student pairs modeling the types of interspecific relationships between organisms in an ecosystem. Materials • Two student volunteers • Props ○ Toy food item ○ Large soda straw • Large index cards ○ Have the cards labeled: • Commensalism • Mutualism • Parasitism • Predation • Competition • Pathogen Procedure & Inquiry 1. Tell the class that two student volunteers or draftees will be modeling the different types of interspecific interactions. 2. Call up two students to the front of the class. 3. Tell them they will model the relationship written on an index card. They must obey the following rules: a. They cannot use words during the modeling demonstration. b. They cannot reveal the word on the index card to the class. c. They can use the props that are provided. 4. Then tell the class that they must guess the interspecific interactions being modeled. 5. Show the two students one of the cards ensuring the rest of class cannot see the word on the card. 6. Have the students act out the interspecific interaction and solicit comments from the class about the type of interaction being portrayed. 7. Summarize the relationships after the demonstration is completed. LABORATORY IDEAS A. Microbial Ecology Lab This activity has students investigate the influence of soil acidification on microbial growth. a. Explain that they will be using soil microbes as a model for looking at the impacts of environmental change. b. Mention that one acid precipitation is one consequence of human activity. c. Provide the students with the following: a. Fresh nutrient broth cultures of the following soil microbes: i. Pseudomonas aeruginosa ii. Bacillus cereus iii. Penicillium bilaiae (or Penicillium from rotting fruit) b. Nutrient broth tubes with 5 ml of the following: i. 4 tubes at pH 7 ii. 4 tubes at pH 5 iii. 4 tubes at pH 4 c. 12 miniature nutrient agar plates at pH 7 d. Sterile 1 ml pipettes e. Vortex mixer if available f. Incubator at 370C g. Fine-tip indelible ink marker h. Dissecting microscope i. Bacterial and fungi key for identifying colonies d. Tell students to set up the experiment as follows (samples must be shaken with vortex mixer or by hand): i. Transfer 1 ml of Pseudomonas aeruginosa to a pH 7 tube. ii. Transfer 1 ml of Pseudomonas aeruginosa to a pH 5 tube. iii. Transfer 1 ml of Pseudomonas aeruginosa to a pH 4 tube. iv. Transfer 1 ml of Bacillus cereus to a pH 7 tube. v. Transfer 1 ml of Bacillus cereus to a pH 5 tube. vi. Transfer 1 ml of Bacillus cereus to a pH 4 tube. vii. Transfer 1 ml of Penicillium bilaiae to a pH 7 tube. viii. Transfer 1 ml of Penicillium bilaiae to a pH 5 tube. ix. Transfer 1 ml of Penicillium bilaiae to a pH 4 tube. x. Transfer 1 ml of each microorganism to a pH 7 tube. xi. Transfer 1 ml of each microorganism to a pH 5 tube. xii. Transfer 1 ml of each microorganism to a pH 4 tube. b. Have students incubate the samples until for at least 48 hours c. Tell the students to transfer 1 ml of the samples to labeled miniature nutrient plates d. Have students incubate the samples until for at least 48 hours e. Tell students to investigate their results and report of the growth of the different organisms. f. Have them investigate the role of each organism in the soil and how they impact their ecosystems. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students volunteer at a nature center. 2. Have students tutor high school students studying ecology. 3. Have student produce an annotated list of readings biodiversity for a local library. 4. Have students volunteer with a conservation group on biodiversity preservation projects CHAPTER 40: THE LIVING WORLD WHERE DOES IT ALL FIT IN? Chapter 40 builds on the foundations of biodiversity and provides detailed information about environmental interactions of organisms. Students should be encouraged to recall the principles of organismic classification and comparative anatomy. The information in chapter 40 does not stand alone. It connects the information on organismic diversity to evolution and ecology coverage. Students should know that animals and other organisms are interrelated and originated from a common ancestor of all living creatures on Earth. SYNOPSIS The final and most inclusive level of organization in the study of ecology is the biosphere. The biosphere represents all of the areas on the Earth that life can exist. It involves all of the biotic and biotic factors and their interplays. Environments vary from one location to another, reflecting changes in the organisms within the biomes. The daily and seasonal fluctuations in weather conditions result from variations in the amount of heat retained by the earth. Such variation ultimately depends on the earth’s rotation around the sun and on its own axis. This latter rotation additionally affects the three major wind circulation patterns. The location of the continental masses alters both the circulation of the winds and the flow of oceanic currents. Variation results from differences in temperature, water, sunlight, elevation, latitude, and soil composition. Organisms cope with environmental variation by eliciting physiological, morphological, or behavioral changes to maintain homeostasis. Other organisms simply conform (tolerate by developing longer fur or undergo hibernation) to the environment or have evolved seasonal migration strategies to cope with the changing conditions. However, no organism can do everything optimally as long as resources are limited. They are forced by the environment to make compromises and must allocate the available resources to a variety of tasks to ensure their survival. Biomes are characteristic collections of plant and animal life dependent on specific climatic and geographical conditions. Terrestrial habitats are grouped into eight major categories (biomes) including tropical rain forests, savannas, deserts, temperate grasslands, temperate deciduous forests, temperate evergreen forests, taiga, and tundra. Other minor biomes include polar ice, mountain zones, chaparrals, warm/moist evergreen forests, tropical monsoon forests, and semidesert. There is a relatively distinct progression of biomes from the equator to the polar latitudes. This progression is mimicked as one ascends mountain ranges. Each biome has characteristic temperatures, seasonal climate, precipitation, and dominant life forms. Although the oceans comprise the majority percentage of the Earth’s surface, they exhibit a relatively small amount of species diversity is exhibited within the ocean. As a whole, the oceanic habitats are quite uniform, comprising only three major zones: neritic, pelagic, and benthic. The neritic zone provides a test area for prospective terrestrial organisms as they are under water part of the time and exposed to air the other part. Abundant nutrients run off the land to supply the vast continental fisheries that has been adversely affected by over fishing and local areas of pollution. The pelagic zone is relatively stable and is composed of planktonic and nectonic life forms. Though microscopic, plankton is enormously important as it accounts for roughly 40% of the Earth’s photosynthesis. The overall productivity of this zone may be grossly underestimated as there is a rapid turnover of nutrients due to the fluctuating plankton populations. The benthic zone is just beginning to be studied by direct observation and the diversity is startling. Life depends on chemosynthesis rather than photosynthesis and has evolved very unique symbiotic strategies. Freshwater habitats are limited in area and strongly tied to terrestrial habitats. They exhibit zones similar to those of open oceans, but on a much smaller scale. There is substantial thermal stratification in some lakes and ponds in both summer and winter. Changing temperatures result in spring and fall overturn of these bodies of water, which results in a redistribution of the nutrients and prevents oxygen depletion in the lower layers. Eutrophic lakes have abundant minerals and organic matter, while oligotrophic lakes are usually scarce in nutrients and organic matter. Deep waters in the latter are often rich in oxygen, making them much more susceptible to phosphate pollution and algal blooms. The productivity and diversity of wetlands is just beginning to be appreciated. Unfortunately, many wetlands have been exploited by human development as they were once thought to be simply useless land. New data collections on organisms are showing a pattern of redistributions, which strongly suggests that climatic regimes are changing worldwide, especially when compared with historical information of those organisms. Either by direct impacts (human health, agricultural practices) or indirect impacts (e.g., rising sea levels), humans are not escaping these changing global conditions. Several human activities are placing the biosphere under tremendous stress. Various types of pollution, acid precipitation from burning fossil fuels for energy production, destruction of the tropical rainforests, ozone depletion and global warming are wreaking havoc worldwide on ecosystems which directly affects the health of the biosphere. The greenhouse effect is disaster in the making as carbon dioxide levels continue to rise. The destruction of the forests aggravates the condition as less carbon dioxide is converted back into oxygen with the existence of fewer plants. Although the oceans have a great capacity to store gases, especially carbon dioxide, there is little data indicating what will happen when the oceans reach their limit. Air and water pollution, acid precipitation, and altered ozone levels are also dangers that know no international boundaries. Industrial pollutants produced by one country are destroying vegetation literally half a world away. Determining the source of such pollution is often all but impossible. World-wide political legislation may be the only cure, but it may not come soon enough. As cataclysmic as the Antarctic ozone hole may be, it has taken years for any world-wide political discussions regarding chlorofluorocarbons to even begin. Increased ultraviolet radiation significantly affects productivity in photosynthetic plankton as well as human health. In addition, the genetic variability of all ecosystems, especially the tropical rain forests, must also be maintained. Scientists have barely scratched the surface of the great variety of life on the entire earth. Ecologists must study what is left of the undisturbed areas to determine the lowest limits, which the rain forests and other communities retain their stability. It will do no good to have small patches of trees or grass in which all vital animal and plant life has disappeared. Investigating all of these problems is the job of the environmental scientist, who is broadly trained in ecology and chemistry. Although species extinction is a normal evolutionary process, humankind has accelerated the rate of species extinctions. Whether because of greed or ignorance, extinctions due to actions of humans are surpassed only by the cataclysmic mass extinctions caused by large body impacts (celestial events) into the Earth’s. As humans invade new territories, they reconstruct the habitat to fit their needs (intentionally or innocently), rarely considering how those changes will affect the native inhabitants. The species that are in the greatest danger of extinction are endemic species that are usually found in isolated geographical areas. All species found on earth today have a value. We humans may not know, understand, or accept that value, but it still exists. Many organisms, like those used for food, clothing, and shelter, have an obvious, direct economic value. Others may have an indirect value where their presence helps maintain a healthy ecosystem. The bugaboo of time travel is that the repositioning of a single grain of sand could alter the entire course of humanity. The loss of a single species may have the same effect on an organism’s ecosystem. Humankind must act as guardians for the diversity of all life since only we have the ability to so readily destroy it. Certain species are more vulnerable to extinction than others because of their endemic distribution, declining population size, lack of genetic variability, and/or hunting pressures by humans. Five factors associated with human activities play key roles in species extinctions. They include overexploitation of a species, introduction of other species into a habitat, disruption of ecological relationships, loss of a species genetic variability and habitat loss and/or fragmentation. As difficult as it can be to recognize which species are vulnerable to extinction, preservation of these species is even more complicated. Recovery programs are complex and expensive. Habitat restoration is imperative as it makes no sense to reintroduce individuals from a captive breeding program into a deficient habitat. Genetic variability must be maintained, but by the time the problem is discovered, it is often too late. Keystone species need to be preserved, though identifying them can be difficult. Whole ecosystems must be conserved, not merely pieces of them or only their most noteworthy species. In some cases it is appropriate to say—“if it’s not broken don’t fix it.” In this case, we humans need to learn to take better care of our belongings to ensure that we do not break them in the first place! Once extinction is complete, the species along with its unique DNA sequences and niche are gone. LEARNING OUTCOMES 40.1 Ecosystems Are Shaped by Sun, Wind, and Water 1. Explain the Coriolis effect. 2. Explain the rain shadow effect. 40.2 Earth Has 14 Major Terrestrial Ecosystems Called Biomes 1. Explain the factors that determine which biome is found in a region. 40.3 Freshwater Habitats Occupy Less Than 2% of Earth’s Surface 1. Explain how the availability of oxygen influences freshwater ecosystems. 2. Distinguish between eutrophic and oligotrophic lakes. 40.4 Marine Habitats Dominate the Earth 1. Describe the major types of ocean ecosystems. 2. Explain why continental shelf ecosystems are more productive than ocean ones. 3. Explain how life is possible in the deep sea. 40.5 Humanity’s Pollution and Resource Depletion Are Severely Impacting the Biosphere 1. Explain how coal-fueled power generation affects deforestation. 2. Describe the effects of ozone depletion. 40.6 Human Activity is Altering Earth’s Climate 1. Describe global warming. 2. Explain the link between atmospheric carbon dioxide and global warming 3. Describe the consequences of global warming on Earth’s ecosystems. COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in Chapter 40 are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. • Students are unaware of the complexity of biomes • Students believe that biomes are fixed entities and therefore static • Students are unfamiliar with microhabitats • Students believe that biomes are solely determined by temperature • Students are unaware the deserts and grasslands are defined by rainfall • Students do not distinguish between habitat and niche • Students do not distinguish between ecosystem and biome • Students think the term biome is synonymous to biosphere • Students are unaware of many abiotic factors in the environment • Students do not make the connection between latitude and biome differences • Students do not make the connection between altitude and biome differences • Students are unaware of evolution at the population level • Student think that selection is directional and produces superior characteristics • Students believe that ecosystems always rebound back to normal after damage • Students view extinction as affecting only that particular organism INSTRUCTIONAL STRATEGY PRESENTATION ASSISTANCE The beginning of this chapter is a review of material students should have received in a general science course in high school or grade school. Some of the most productive agricultural regions are temperate grassland biomes. Relate the nature of the agricultural crops to the natural crops. Extrapolate on ways to convert other biomes into productive food-growing regions. Discuss the advantages and disadvantages of keeping a region’s nutrients tied up in living organisms. Such biomes are generally considered nutrient-poor, and exhibit low productivity even though they exhibit great numbers of organisms. The topics presented in this chapter are the regular fare of newspapers, magazines, and television. Since the last edition of this textbook, many localities have enacted more stringent air and were pollution controls and have begun recycling paper, plastics, cans, and glass. Many citizens mulch garden and lawn wastes, and restrict their use of pesticides, herbicides, and fertilizers. Volunteer groups clean up parks, beaches, and waterways. Who would have guessed 5 years ago that a magazine called Garbage would thrive and that consumers would want to buy paper towels made from recycled paper? Such ecological activities are in vogue and will hopefully become permanent lifestyle changes in all of us. A necessary accompaniment to these activities is education, perhaps of adults more so than small children. The young children know that we adults will probably never see the culmination of the environmental problems our wasteful attitudes have caused—but they will! Although CFC propellants no longer stream from spray cans, they still leak from discarded refrigerators, air conditioners, and various chemical processes. Discuss engineering bacteria to degrade pollutants (plastics, oil spills). Include the many safeguards that are added to prevent potential disaster in terms of degradation of desired materials (insulation, plastic containers, housing products, natural oil reserves) in addition to the wastes and toxins. So much of what we use is made of some form of plastic—a totally unnatural product that is not biodegradable. Most people don’t realize that a plastic jug or fishing line will be intact hundreds of years from now. To demonstrate the amount of tropical rainforests that can disappear in a semester of class, do the following in class activity. If it assumed that 160,000 sq. KM are cut in a year, then calculation can be made to determine how much in a day and hour, even minute. Next multiply that amount by the number of minutes in the class period then the number of class periods in a semester, and the amount is calculated. This type of data should offer an excellent message to the future scientists enrolled in this course that something has to be done to curb that activity. Introduced species include kudzu in the southern Unites States and cane toads, rats, and cats in Australia. American dandelions are an introduced species (from England). European rabbits were introduced into Australia and have managed to remain quite viable despite numerous efforts to eliminate them over decades of time. Naturalists have a great fear of dogs and cats destroying the populations of iguanas in Galapagos Islands. There are many cases where humans have accidentally introduced harmful species, then introduced another species to control introduced species; that species then becomes a problem when (if) the accidentally introduced species is controlled. There are other examples where humans introduce species for their own benefit—not being aware of (or more likely, not caring about) the overall effects to the natural environment. If internet connections are available in class, have students use a metasearch engine (www.Dogpile.com or Google) with the following string of terms—“introductions + flora + fauna + United + States” and discuss the results in class. There is an interesting article in Discover (August 2000) magazine about the importance of parasites in ecosystems. The author contends that even though parasites are considered harmful to their hosts, the loss of a single one could grossly disrupt its ecosystem. He provides several examples including a snail fluke and a killifish brain parasite. In the first, if the fluke is eradicated, the snail population nearly doubles and thins out the algae carpet in the salt marsh. In the second, the parasite alters the behavior of the fish, enabling it to be captured more readily by local bird populations, thereby helping to sustain them. Another case study examines the Riddly sea turtles. Eggs from eastern Mexican beaches are caught as mothers lay them. They are placed in sand from certain beaches in Texas and hatched in incubators. Hundreds have been released into Gulf off eastern Texas over the past 10 years. Recently, scientists have found 12 nests on beaches already this year where none existed before. The translocation is, so far, successful. The process continues to ensure a maximum rate of hatching and survival. It was accidentally discovered that higher incubation temperatures result in all turtles becoming female. The researchers now incubate at that temperature to increase the numbers of females in the wild, more effectively populating the Texas habitats. This is a “current events” kind of chapter. It is extremely important to be aware of the recent political and environmental issues worldwide, but especially those in your own area. Will a new mall affect the drainage patterns of a creek and the possible local extinction of a snail, insect, amphibian, or aquatic plant, or perhaps a nesting area for a particular bird species? The general public often considers scientific studies of ecosystems to be a waste of money. It is important to characterize them so that we have data to restore them after we have screwed them up! Ecological characterization is quite cheap compared to molecular/medical research. Although if offers little financial gains, it is ethically and aesthetically important. Ask guest speakers (Earthwatch, Sierra Club, Audubon Society) to come to your class and make brief comments on actual case studies where their efforts have made a difference either in a species recovery or a habitat restoration. HIGHER LEVEL ASSESSMENT Higher level assessment measures a student’s ability to use terms and concepts learned from the lecture and the textbook. A complete understanding of biology content provides students with the tools to synthesize new hypotheses and knowledge using the facts they have learned. The following table provides examples of assessing a student’s ability to apply, analyze, synthesize, and evaluate information from Chapter 40. Application • Have students explain how an increase in solar radiation would affect an aquatic biome. • Have students explain the influence of altitude on determining the type of biome in an area. • Ask students to explain why crop irrigation is needed in areas that were once grasslands. • Have students explain how environmental disruption can cause the extinction of a species of birds. • Have students explain why the extinction of one species can cause the overpopulation of another. • Ask students how the introduction of invasive species can lead to the loss of native species in a hotspot. Analysis • Have students explain how fresh water biomes interact with temperature forest biomes. • Have student describe how the depletion of atmospheric ozone could affect agriculture. • Ask students to explain why cooling of certain parts of the Earth is still evidence of global warming. • Have students explain the difference between conservation and preservation. • Have student contrast the types of human activities that caused extinctions in ancient times compared to today. • Ask students how genomic analyses are assisting with the preservation of endangered organisms. Synthesis • Ask students to design an experiment to investigate the effects of deforestation on freshwater biomes. • Have students find a commercial application for the fact that plants in tropical rain forest biomes must protect themselves from the greatest number of plant-eating pests than found in any other biome. • Ask the students to explain the possible effects of antibiotics entering aquatic biomes from septic and sewage systems. • Ask students find a use for plant tissue culture in the conservation of tropical rain forests. • Have students design an experiment to investigate the effects of global climate change on extinctions in arctic environments. • Ask the students come with a strategy for reducing the impacts of deforestation associated with suburban growth. Evaluation • Ask students debate the role of reducing automobile emissions as a strategy for reducing global warming. • Ask students to access a strategy of protecting ocean biomes are artificially inflating the cost of seafood so that it was very expensive to purchase. • Ask students evaluate a plan to revert large areas of “unproductive” desert into “fertile” agricultural lands. • Ask students assess pros and cons of using genetic engineering to bring back extinct species of animals for reintroduction into their native habitats. • Ask students to evaluate the pros and cons of killing off mosquitoes that spread human diseases in tropical areas. • Ask students present an argument for preserving a keystone species of fish in your area. VISUAL RESOURCES Photos of various biomes are a must. Do not merely flash a slide of a grassland and say “See... a temperate grassland.” Point out the dominant plants and animals and compare them from biome to biome. Nearly every biome has some very large angiosperm and some form of large grazing mammal as well as short ground cover and small seed-eating rodents, birds, or insects. Be sure to identify the locations of various biomes on a globe or world map. Many students are very weak in world (and even U.S.) geography. Students can see the major ocean currents, as well as visualize solar radiation distribution if the Earth’s tilt is discussed. Show photographs of fossil fuel fired electrical generating plants. Emphasize the pollution. This leads to the discussion of the chemistry of sulfur and nitrogen oxides, which can combine with water vapor in the atmosphere to form acid precipitation. Next show photographs of the damage that is caused by acid precipitation to help students make the connection between electrical production and vegetation damages. Rent the movie Medicine Man starring Sean Connery. Connery’s character is engaged in research in the rain forest, looking for a chemical cure for cancer based on stories of the indigenous peoples. To spoil the story—he thinks the compound is an isolate from an epiphytic plant, but it turns out that the compound is associated with the ants that inhabit the plant. Of course, he finds this all out after the area in which he is working is destroyed by fire and a road-building crew! Photos of the various forms of pollution and the effect on living organisms can be quite sobering. Especially graphic are those that show birds strangled by the plastic webbings that hold six packs of cans together. A demonstration for those who use an overhead projector: Collect several objects or simple shapes and show them to the class. Turn off the lamp and place the objects on the overhead, covering half of it (objects and all) with cardboard. Turn the lamp back on and ask the students to remember the placings of all of the objects. Then tell them that you will give an “A” to anyone who can correctly place all of the objects. Of course they will begin to complain that they cannot complete the task because they did not see where half of the items were located due to the cardboard. Ah ha—precisely why it is so difficult to restore any habitat to a pristine condition! This is where television can be a real asset to teaching. Contact your local PBS station and/or cable communications (The Learning Channel, Discovery Channel, the Animal Planet are among the best) to find out what programs of interest may be broadcast during the appropriate semester. It is unlikely that you will have either the time or resources to show such films in class (make it an outside class required assignment if you can). (If not somehow tested upon, very few students will view the resources. And those that need to be enlightened the most will be least likely to get it.) Tons of “favorite” animal and plant web sites exist. Many are factually correct and well known; others are drivel. Find or create a website as class assignment to inform students about conservation biology as well as the value and operation of the internet. There is an excellent article entitled “Conserving Biodiversity’s Coldspots,” pages 344-351, American Scientist, Vol. 91, July-August 2003. Have students collect and bring to class any news article (newspaper or popular magazine) relating to conservation efforts around the Earth. Display a collection of these articles during class to make an impact on student thinking related to conservation efforts. IN-CLASS CONCEPTUAL DEMONSTRATIONS A. Making a Biosphere Introduction This demonstration has the instructor lead students through a series of queries about the criteria needed for replicating the Earth’s biome into a functional biosphere. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser linked to Biosphere 2 photo Gallery website at http://www.bio2.com/gallery.htm and Biosphere 2 Virtual Tour at http://www.bio2.com/tourinfo.htm Procedure & Inquiry 1. Tell the class they will be viewing a research project called Biosphere 2 build near Tucson, Arizona. 2. First, ask the class if it would be possible to replicate a miniature Earth as seen in many science fiction movies about space travel. 3. Load up the Biosphere 2 photo galley. 4. Ask the class to describe what they see in the images. 5. Then go to the Biosphere 2 Virtual Tour website and click on the following tours: a. Desert b. Mangroves c. Ocean d. Rainforest 6. Have the students describe the reality of the biomes that were created and if the interrelationship between the different biomes reflects the biosphere.. B. A Bird’s Eye View of Local Conservation Needs Introduction This demonstration has the instructor lead students through the rationale that biologists use to define biodiversity loss hotspots. Materials • Computer with Media Player and Internet access • LCD hooked up to computer • Web browser with previously downloaded Google Earth at http://earth.google.com/ • Google Earth on computer desktop Procedure & Inquiry 7. Tell the class they will be viewing aerial images of their area using Google Earth 8. Click on the Google Earth icon 9. Add “Roads” , “Terrain”, “Borders”, and “Buildings” to the view as a reference point for students to identify particular features of the area 10. Toggle the “Earth Image” to your region and slowly zoom in 11. The “Roads” can be removed when looking at close up view to prevent road labeling from covering terrain features. 12. Other details can be added or subtracted using the “Layers” window. 13. Ask the students to assess the development of their area and identify areas conducive to sustainable wildlife populations. 14. Ask the students to identify areas that may cause environmental decay. 15. Have students assess the particular features of building developments and roadways that sector the area into isolated habitats or ecosystems. LABORATORY IDEAS A. Affects of Extinction on Ecosystem Changes This activity has students design an experiment to that models the effects of extinctions on an ecosystem. a. Explain to the students the concept and principles of extinction. b. Then tell them that they will design an experiment to investigate how extinctions can impact a biome. c. Provide the students with the following: a. Protected area of campus or a park to conduct a field experiment b. Items for changing microclimate i. Water at various pHs ii. Plastic cups iii. Foil or tarp material iv. Mesh or screening v. Rope and tent pegs vi. Other materials requested by students d. Tell them that they will use the materials in way that excludes an organism from a small patch of the area under study. e. The students should be instructed to consider what to use as a control and how to compare any changes in the experimental conditions. f. Have the students prepare an illustrated poster session of their findings for presentation to the whole class. B. Sustainability Laboratory This activity has students develop a rationale and sustainable way of using natural resources that are used in everyday life. a. Explain that they will be placed into brainstorming groups. b. Then tell them that each group will be charged with finding a sustainable way of using a current resource or technology. c. Have the students review the topic of sustainability with a web search. d. Provide the students with the following: a. Group 1: Metal food cans b. Group 2: Hard plastic case used in retail merchandise c. Group 3: Food item d. Group 4: Pesticide bottle e. Group 5: Construction brick f. Group 6: Cardboard box e. Ask the students to record and summarize their findings after the brainstorming session. f. Tell them that each group will present their proposed sustainable idea to the class for discussion. LEARNING THROUGH SERVICE Service learning is a strategy of teaching, learning and reflective assessment that merges the academic curriculum with meaningful community service. As a teaching methodology, it falls under the category of experiential education. It is a way students can carry out volunteer projects in the community for public agencies, nonprofit agencies, civic groups, charitable organizations, and governmental organizations. It encourages critical thinking and reinforces many of the concepts learned in a course. 1. Have students volunteer at a nature center. 2. Have students tutor high school students studying ecology. 3. Have students produce a biomes PowerPoint presentation for area high school teachers. 4. Have students host a litter cleanup campaign for the area. 5. Have students volunteer at a community recycling center. 6. Have students do a public information presentation on natural resource conservation for a local civic group. 7. Have students volunteer with a conservation group on environmental preservation projects. Instructor Manual for Understanding Biology Kenneth Mason, George Johnson, Jonathan Losos, Susan Singer 9780073532295, 9781259592416
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