Campbell Biology Ap 334t6p

Name _______________________ Period ___________

Chapter 51: Animal Behavior This chapter may be one of your favorites, as it will cause you to consider behaviors you have noticed, and lead you to question how the behavior could affect natural selection. Behaviors in the individual serve to increase its fitness in the population and are vital to reproduction, and survival. Throughout the year, there has been an emphasis on communication, with signaling and responses. In this chapter you see that this occurs not just at a cellular level, but also at the level of the organism and population. There are myriad environmental cues that elicit responses. EK 2.E.3, Timing and coordination of behavior are regulated by various mechanisms and are important in natural selection, and EK 3.E.1, Individuals can act on information and communicate it to others, are covered in this important chapter, along with many associated learning objectives. Overview 1. How is behavior defined? Why are behaviors subject to natural selection? A behavior is an action carried out by muscles under control of the nervous system in response to a stimulus. Behaviors are subject to natural selection because they are essential for survival and reproduction. Concept 51.1 Discrete sensory inputs can stimulate both simple and complex behaviors 2. Nicholas Tinbergen’s work with the stickleback fish is a classic study. Explain what he found using the fixed action pattern and sign stimulus in your response. Nicholas Tinbergen found that the color red is a sign stimulus triggering a fixed action pattern of aggressive behavior in male stickleback fish. 3. What is migration? Migration is a regular, long-distance change in location. 4. Explain what is meant by circadian clock and circadian rhythms. Identify two behaviors, either plant or animal, that demonstrate a circadian rhythm. (You may need to refer to Chapter 40 or Chapter 49 for examples.) A circadian clock is an internal mechanism that maintains a 24-hour activity rhythm or cycle. A circadian rhythm is the output of a circadian clock, a daily cycle of rest and activity with far-reaching effects on behavioral physiology. The sleep/wake cycle of humans is one example of a circadian rhythm. A plant example is the opening of the morning glory flowers—they open in the morning and then close in the late afternoon. Copyright © 2015 Pearson Education, Inc.

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5. Discuss two navigational strategies used by birds to migrate. Some migrating birds track their position relative to the sun. These animals adjust for changes in the sun’s position relative to the Earth throughout the day by means of a circadian clock. Nocturnal animals can instead use the North Star. Pigeons are able to sense their position relative to the Earth’s magnetic fields and are thereby able to navigate without solar or celestial clues. 6. Animals communicate in various ways. Discuss at least three specific examples using different organisms. In their courtship dance, male and female fruit flies communicate using visual, chemical, tactile, and auditory signals. The male visually recognizes the female, while the female releases chemicals detected by the male’s sense of smell. The male taps the female’s abdomen with a foreleg and vibrates his wings to produce a song. This singing informs the female that the male is of her same species and only then does she allow him to attempt copulation. Returning bees use different types of dance (the “round dance” and the “waggle dance”) to communicate information to the rest of the hive about the location of food. This is visual communication. Minnows and catfish, when injured, release a substance from their skin that induces a fright response in other fish. This is an example of chemical communication. 7. Figure 51.4 shows fruit fly courtship behavior. What different modes of communication are used by the fruit fly? The modes of communication used by the fruit fly are visual, chemical, tactile, and auditory. 8. Karl von Frisch studied European honeybees. What are the two types of dances that a returning worker bee does, and what information does each dance convey? Use a labeled sketch to describe each dance. If the food source is close to the hive (less than 50 m away), the returning bee moves in tight circles while waggling its abdomen from side to side. This behavior, called the “round dance,” motivates the follower bees to leave the hive and search for nearby food. When the food source is farther from the nest, the returning bee instead performs a “waggle dance.” This dance, consisting of a half-circle swing in one direction, a straight run during which the bee waggles its abdomen, and a half-circle swing in the other direction, communicates to the follower bees both the direction and distance of the food source in relation to the hive. The angle of the straight run relative to the hive’s vertical surface is the same as the horizontal angle of the food in relation to the sun. For example, if the returning bee runs at a 30° angle to the right of vertical, the follower bees leaving the hive fly 30° to the right of the horizontal direction of the sun. A dance with a longer straight run, and therefore more abdominal waggles per run, indicates a greater distance to the food source. For help with your sketch, see page 1137 of your text. Copyright © 2015 Pearson Education, Inc.

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9. What are pheromones? Give three specific types of information that can be transmitted through pheromones. Pheromones are chemical substances emitted by animals that are used to communicate through odors or taste with of their own species. They can transmit information about sex, social order, and alarm signals. Concept 51.2 Learning establishes specific links between experience and behavior 10. What is the difference between innate and learned behavior? Give an example of each and describe how the behavior increases fitness. Innate behavior is developmentally fixed, and nearly all individuals in a population will exhibit virtually the same behavior despite internal and environmental differences during development and throughout life. In learned behavior, behavior is variable, depending on experience. Learned behavior results from the modification of behavior based on specific experiences. Pheromone signaling is an example of an innate behavior, whereas aggressiveness in male mice is learned. In pheromone signaling, compatible signal emission and detection by a potential mate improves the chances of successful reproduction. Aggressiveness in mice may help to ensure reproductive success by establishing clear boundaries for mating territories. 11. Describe the process of imprinting, and explain what is meant by sensitive or critical period. Imprinting is the formation at a specific stage in life of a long-lasting behavioral response to a particular individual or object. Imprinting is distinguished from other types of learning by having a sensitive period, also called a critical period, a limited developmental phase when this type of learning can occur. During the sensitive period, the young imprint on their parent and learn the basic behaviors of their species, while the parent learns to recognize its offspring. 12. Describe the classic study of parental imprinting done by Konrad Lorenz. Lorenz found that when incubator-hatched goslings spent their first few hours with him rather than with a goose, they imprinted on him and showed no recognition of their biological mother or of adults of their own species. 13. Many bird songs are learned during a sensitive period. What will happen if a white-crowned sparrow does not hear the song of its species during this time? If a fledgling is prevented from hearing real sparrows or recordings of sparrow songs during the first 50 days of its life, it fails to develop the adult song of its species. 14. What special challenges did researchers face in order to return whooping cranes to the wild? What would you have to wear if you worked with hatchlings? Why? Scientists tried raising whooping cranes in captivity by using sand hill cranes as foster parents.

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However, because the whooping cranes imprinted on their foster parents, none formed a pair-bond (strong attachment) with a whooping crane mate. To avoid such problems, captive breeding programs now isolate young cranes, exposing them to the sights and sounds of of their own species. People who work with whooping cranes in captivity wear “crane suits” so they look like big whooping cranes to prevent imprinting of the cranes on humans. 15. There are several types of learning. What occurs in spatial learning? In spatial learning the animal establishes a memory that reflects the environment’s spatial structure. 16. What are two types of associative learning? Which type did Ivan Pavlov use to get a dog to salivate at the sound of a bell? Two types of associative learning are classical conditioning and operant conditioning. Pavlov used classical conditioning to get a dog to salivate at the sound of a bell. 17. What occurs in operant conditioning? In operant conditioning, also called trial-and-error learning, an animal first learns to associate one of its behaviors with a reward or punishment and then tends to repeat or avoid that behavior. 18. What is cognition? Give three examples of cognition in animal species; include at least one bird behavior among them. Cognition involves the most complex form of learned behavior. Animals that are able to solve problems show cognition. Honeybees that are able to be trained to respond to a stimulus to reach a food reward show cognition. Primates are able to solve problems, which shows cognition. For example, a chimp will pile up boxes to reach a banana hung high in a room. The crow family (called the corvids) includes crows and ravens. Ravens have demonstrated the ability to solve problems, such as how to pull food hanging by a string up to eat. Again, this problem-solving ability is an example of cognition. Concept 51.3 Selection for individual survival and reproductive success can explain diverse behaviors 19. What is foraging behavior? Food-obtaining behavior, or foraging, includes not only eating but also any activities an animal uses to search for, recognize, and capture food items. 20. What is proposed by the optimal foraging theory? Explain it in of cost and benefit, and cite two examples from your text. Copyright © 2015 Pearson Education, Inc.

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According to this optimal foraging model, natural selection should favor a foraging behavior that minimizes the costs of foraging and maximizes the benefits, such as energy gain. The scientific skills exercise that discusses crow foraging behavior on page 1144 provides a good example of this. Mule deer are also subject to the optimal foraging model when predation risk influences foraging behavior. 21. To demonstrate that you understand the principle of optimal foraging, describe a food source that you would not be likely to exploit and explain why. Students could give a variety of answers here to indicate the relative energy expense of hunting for very small food bits—we would not, for example, choose searching for blueberries or ants to our energy needs, given the option of larger food bits. 22. There are a number of different possible mating systems. For each, give an example of a species that uses the system and an underlying evolutionary benefit of the system. promiscuity: No strong pair bonds. Snowshoe hares are known to be promiscuous. Promiscuity is likely to occur in unpredictable or changing environments. A promiscuous mating system increases the likelihood of having offspring. monogamy: One male mates with one female. Western gulls are an example. Parental care is greater in these systems, and a male that stays and helps a single mate may ultimately have more viable offspring than it would by going off to seek additional mates. polygamy: An individual of one sex mates with several of the other. Examples of the two main types are discussed below. polygyny: A single male mates with many females. Elk are an examples. Sexual dimorphism is common and males are generally more ornamented, promoting female mate choice for the male with the best genes. This increases the reproductive fitness within the population by increasing reproduction with the most healthy, dominant males. polyandry: A single female mates with several males. Sexual dimorphism is common, but females are generally more ornamented. In red-necked phalaropes, females mate with a male, then leave him to care for the offspring while she goes to seek another mate and lay another clutch of eggs. This increases the fitness of the individuals in that the female can spend more time reproducing and less time with maternal care of offspring. 23. Explain two factors that may be important in determining the evolution of these systems, and apply each factor to a particular species. The needs of the young are an important factor constraining the evolution of mating systems. Most newly hatched birds, for instance, cannot care for themselves. Rather, they require a large, continuous food supply, a need that is difficult for a single parent to meet. In such cases, a male that stays with and helps a single mate may ultimately have more viable offspring than it would by going off to seek additional mates. This may explain why most birds are monogamous.


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Another factor influencing mating behavior and parental care is certainty of paternity. Young born to or eggs laid by a female definitely contain that female’s genes. However, even within a normally monogamous relationship, a male other than the female’s usual mate may have fathered that female’s offspring. The certainty of paternity is relatively low in most species with internal fertilization because the acts of mating and birth (or mating and egg laying) are separated over time. This could explain why exclusively male parental care is rare in bird and mammal species. However, the males of many species with internal fertilization engage in behaviors that appear to increase their certainty of paternity. These behaviors include guarding females, removing any sperm from the female reproductive tract before copulation, and introducing large quantities of sperm that displace the sperm of other males. 24. Let’s return to an earlier idea from Chapter 23. What is sexual selection? Sexual selection is a form of natural selection in which differences in reproductive success among individuals are a consequence of differences in mating success. 25. There are two types of sexual selection. Explain each of them. intersexual selection: of one sex choose mates on the basis of characteristics of the other sex, such as courtship songs. intrasexual selection: Competition between of one sex for mates. 26. How can mate choice increase fitness? An individual whose mate choice is a healthy one is likely to produce more offspring that survive to reproduce. 27. What is agonistic behavior? Give one example of this behavior that is not in your book. Agonistic behavior is an often-ritualized contest that determines which competitor gains access to a resource, such as food or mates. One example might be the combative behavior between male deer seen during mating season. 28. How can game theory be applied to evolutionary problems of reproductive success? Game theory provides a way to think about complex evolutionary problems in which relative performance (reproductive success relative to other phenotypes), not absolute performance, is the key to understanding the evolution of behavior. This makes game theory an important tool because the relative performance of one phenotype compared with others is a measure of Darwinian fitness. Concept 51.4 Genetic analyses and the concept of inclusive fitness provide a basis for studying the evolution of behavior 29. Explain how the fru gene demonstrates a genetic basis of behavior.


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During courtship, the male fruit fly carries out a complex series of actions in response to multiple sensory stimuli. Genetic studies have revealed that a single gene called fru controls this entire courtship ritual. If the fru gene is mutated to an inactive form, males do not court or mate with females. (The name fru is short for fruitless, reflecting the absence of offspring from the mutant males.) 30. What is altruism? The term altruism describes a behavior that reduces an animal’s individual fitness but increases the fitness of other individuals in the population. 31. Explain the evolutionary advantage to a population of having who exhibit altruistic behavior. When individuals exhibit altruistic behavior, they enhance the survival of other of the group. When these individuals are closely related, genetic fitness is enhanced. 32. Altruism may reduce the fitness of an individual—for example, by making that individual more obvious to a predator. Explain this behavior using the concept of inclusive fitness. The selection for altruistic behavior is most readily apparent in the case of parents sacrificing for their offspring. When parents sacrifice their own well-being to produce and aid offspring, this actually increases the fitness of the parents because it maximizes their genetic representation in the population. However, individuals sometimes help others who are not their offspring. 33. Explain the logic behind geneticist J.B.S. Haldane’s comment that he would lay down his life for two brothers or eight cousins. Siblings have an r of 0.5, and between first cousins, r = 0.125 (1⁄8). So, rescuing 2 brothers would be 2(0.5) = 1 and rescuing 8 cousins would be 8(0.125) = 1. In both cases, this would save the genetic equivalent of the rescuer. 34. Contrast kin selection and reciprocal altruism. Kin selection favors altruistic behavior by enhancing the reproductive success of relatives. With reciprocal altruism, the behavior is adaptive if the aided individual returns the favor in the future. Test Your Understanding Answers Now you should be ready to test your knowledge. Place your answers here: 1. c

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Chapter 52: An Introduction to Ecology and the Biosphere What determines which organisms will be found in an area? In this chapter, you will learn about the roleof climate in affecting this distribution. Overview 1. What is ecology? Ecology is the scientific study of the interactions between organisms and the environment. 2. Study Figure 52.2 in your text. It shows the different levels of the biological hierarchy studied by ecologists. Notice also the different types of questions that might be studied by an ecologist at each level of study. Use this figure to develop a flowchart of the hierarchy from most to least inclusive. See page 1159 for the labeled figure with descriptions. Concept 52.1 Earth’s climate varies by latitude and season and is changing rapidly 3. What is climate? What four factors are its components? Climate describes the long-term, prevailing weather conditions in a given area. Four physical factors— temperature, precipitation, sunlight, and wind—are particularly important components of climate. 4. What is the difference between macroclimate and microclimate? Macroclimate describes patterns on the global, regional, and landscape level. Microclimate describes very fine, localized patterns, such as those encountered by the community of organisms that live in the microhabitat beneath a fallen log. 5. Study Figures 52.3 and 52.4 in your text, which summarize Earth’s climate patterns and how they are formed. Explain how Earth’s curvature and axis of rotation influence the amount of sunlight reaching a given area—for our purposes Miami and Chicago—and how these factors influence the temperature, precipitation, and levels of photosynthesis in that area. See pages 1160–1161 in your text for the labeled figure. Earth’s curved shape causes latitudinal variation in the intensity of sunlight. Because sunlight strikes the tropics (those regions that lie between 23.5° north latitude and 23.5° south latitude) most directly, more heat and light per unit of surface area are delivered there. Miami is relatively close to the tropics. At higher latitudes, such as Chicago, sunlight strikes Earth at an oblique angle, and thus the light energy is more diffuse on Earth’s surface.


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Intense solar radiation near the equator initiates a global pattern of air circulation and precipitation. High temperatures in the tropics evaporate water from Earth’s surface and cause warm, wet air masses to rise and flow toward the poles. The rising air masses release much of their water content, creating abundant precipitation in tropical regions. As a result of the abundant precipitation and more direct sunlight, levels of photosynthesis are highest in these tropical regions. The high-altitude air masses, now dry, descend toward Earth around 30° north and south, absorbing moisture from the land and creating an arid climate conducive to the development of the deserts that are common at those latitudes. Some of the descending air then flows toward the poles. At latitudes around 60° north and south, the air masses again rise and release abundant precipitation (although less than in the tropics). Some of the cold, dry rising air then flows to the poles, where it descends and flows back toward the equator, absorbing moisture and creating the comparatively rainless and bitterly cold climates of the polar regions. 6. Explain the “rain shadow” effect. When warm, moist air approaches a mountain, the air rises and cools, releasing moisture on the windward side of the peak (see Figure 52.6). On the leeward side, cooler, dry air descends, absorbing moisture and producing a “rain shadow.” 7. What effect does elevation have on climate? Why do we say that hiking from Gatlinburg, Tennessee, at 393 meters of elevation in the Smoky Mountains region, to the top of Mount LeConte, at 2,010 meters, is like traveling to Canada? Every 1,000-m increase in elevation produces an average temperature drop of approximately 6°C, equivalent to that produced by an 880-km increase in latitude. This is one reason that high-elevation communities at one latitude can be similar to those at lower elevations much farther from the equator. 8. Every environment on Earth is characterized by abiotic or nonliving factors and biotic or living factors. 9. Use the example of the beech tree to explain how global climate change can alter the current range of species. Ecology models predict that the northern limit of the American beech’s range may move 700–900 km northward in the next century, and its southern range limit will shift even more as a consequence of the global warming predicted for this century. Concept 52.2 The structure and distribution of terrestrial biomes are controlled by climate and disturbance 10. What is a biome? A biome is a major life zone characterized by vegetation type (in terrestrial biomes) or by the physical environment (in aquatic biomes). 11. Figure 52.9 in your text shows a climograph for some major biomes in North America. What two abiotic factors shown here are most important in determining the distribution of the biome?


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Annual mean temperature and annual mean precipitation 12. Label the axes of this figure, and identify each biome shown. Try to do this based on your understanding of the figure, and then use the text to check your answers. You will use these biomes:temperate grassland, temperate broadleaf forest, tropical forest, northern coniferous forest, desert, and tundra. See page 1165 of your text for the labeled figure. 13. The energy budget of a biome is set by its level of photosynthesis. In general, warm temperatures and abundant rainfall translate to high levels of photosynthesis and biomes with high energy budgets. a. Which biome has the highest energy budget and, consequently, the greatest species diversity? Tropical rainforest b. Which biome would you predict has the lowest energy budget? Tundra c. What effect would you expect global warming to have on the total area of the northern coniferous forest? Global warming will likely reduce the total area of the northern coniferous forest. Concept 52.3 Aquatic biomes are diverse and dynamic systems that cover most of Earth 14. What is the largest marine biome, and how much of Earth’s surface does it cover? The oceans make up the largest marine biome, covering about 75% of Earth’s surface. 15. As you read this section and study Figure 52.14 in your text, you will encounter a number of new ideas about aquatic biomes. Although it is not necessary to memorize a vast amount of data, a few trends should be part of your general biology knowledge, a knowledge base that will ultimately help you with a wide variety of questions. The following questions will give you a starting outline. a. How do oligotrophic and eutrophic lakes differ? Oligotrophic lakes are nutrient poor and generally oxygen rich. Eutrophic lakes are nutrient rich and often depleted of oxygen. b. Why do ecologists consider preservation of wetlands important in maintaining water quality? Wetlands have a high capacity to filter dissolved nutrients and chemical pollutants and reduce peak flooding. c. Rate the productivity of wetlands relative to other biomes. Wetlands are among the most productive biomes on Earth. d. What are the two most important physical characteristics of streams and rivers? The speed and volume of their flow e. What is an estuary? What characteristic do they share with wetlands? An estuary is a transition between river and sea. Nutrients from the river make estuaries, like wetlands, among the most productive biomes. f. What is the intertidal zone? The periodically submerged and exposed zone between low and high tidal fluctuations that occur on most marine shores g. How have coral reefs been affected by human activities? Collecting of coral skeletons and overfishing have reduced populations of corals and reef fishes. Global warming and pollution may be contributing to large-scale coral death.


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h. What is unique about the producers in deep-sea hydrothermal vents? Would you expect these ecosystems to have high or low energy budgets? In these dark, hot environments, the food producers are chemoautotrophic prokaryotes that obtain energy by oxidizing H2S formed by a reaction of the hot water with dissolved sulfate (SO42–). These ecosystems have a generally low energy budget. Concept 52.4 Interactions between organisms and the environment limit the distribution of species 16. What role does dispersal play in the study of the distribution of species? One factor that contributes greatly to the global distribution of organisms is dispersal, the movement of individuals or gametes away from their area of origin or from centers of high population density. A biogeographer who studies the distributions of species in the context of evolutionary theory might consider dispersal in hypothesizing why there are no kangaroos in North America: A barrier may have kept them from reaching the continent. Although land-bound kangaroos have not reached North America under their own power, other organisms that disperse more readily, such as some birds, have. The dispersal of organisms is critical to understanding the role of geographic isolation in evolution as well as the broad patterns of species distribution we see today. 17. Give an example of how one species can affect the distribution of another species. Biotic factors that may help explain the distribution of species include predation, herbivory, the presence or absence of pollinators, food resources, parasites, pathogens, and competing organisms. 18. List five abiotic factors. Include an example and description of each factor’s influence on living organisms. Abiotic Factor

Example and Description

Temperature

Environmental temperature is an important factor in the distribution of organisms because of its effect on biological processes. Cells may rupture if the water they contain freezes (at temperatures below 0°C), and the proteins of most organisms denature at temperatures above 45°C. Most organisms function best within a specific range of environmental temperature. Temperatures outside that range may force some animals to expend energy in regulating their internal temperature, as mammals and birds do (see Chapter 40). Extraordinary adaptations enable certain organisms, such as thermophilic prokaryotes (see Chapter 27), to live outside the temperature range habitable by other life.


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Water and oxygen

Salinity

Sunlight

The dramatic variation in water availability among habitats is another important factor in species distribution. Species living at the seashore or in tidal wetlands can desiccate (dry out) as the tide recedes. Terrestrial organisms face a nearly constant threat of desiccation, and the distribution of terrestrial species reflects their ability to obtain and conserve water. Many amphibians, such as the harlequin toad in Figure 52.1, are particularly vulnerable to drying because they use their moist, delicate skin for gas exchange. Desert organisms exhibit a variety of adaptations for acquiring and conserving water in dry environments. Water affects oxygen availability in aquatic environments and in flooded soils. Because oxygen diffuses slowly in water, its concentration can be low in certain aquatic systems and soils, limiting cellular respiration and other physiological processes. Oxygen concentrations can be particularly low in both deep ocean and deep lake waters and sediments where organic matter is abundant. Flooded wetland soils may also have low oxygen content. Mangroves and other trees have specialized roots that project above the water and help the root system obtain oxygen. Unlike many flooded wetlands, the surface waters of streams and rivers tend to be well oxygenated because of rapid exchange of gases with the atmosphere. The salt concentration of water in the environment affects the water balance of organisms through osmosis. Most aquatic organisms are restricted to either freshwater or saltwater habitats by their limited ability to osmoregulate. Although most terrestrial organisms can excrete excess salts from specialized glands or in feces or urine, salt flats and other high-salinity habitats typically have few species of plants or animals. Salmon that migrate between freshwater streams and the ocean use both behavioral and physiological mechanisms to osmoregulate. They adjust the amount of water they drink to help balance their salt content, and their gills switch from taking up salt in fresh water to excreting salt in the ocean. Sunlight absorbed by photosynthetic organisms provides the energy that drives most ecosystems, and too little sunlight can limit the distribution of photosynthetic species. In forests, shading by leaves in the treetops makes competition for light especially intense, particularly for seedlings growing on the forest floor. In aquatic environments, every meter of water depth selectively absorbs about 45% of the red light and about 2% of the blue light ing through it. As a result, most photosynthesis in aquatic environments occurs relatively near the surface. Too much light can also limit the survival of organisms. In some ecosystems, such as deserts, high light levels can increase temperature stress if animals and plants are unable to avoid the light or to cool themselves through evaporation (see Chapter 40). At high elevations, the sun’s rays are more likely to damage DNA and proteins because the atmosphere is thinner, absorbing less ultraviolet (UV) radiation. Damage from UV radiation, combined with other abiotic stresses, prevents trees from surviving above a certain elevation, resulting in the appearance of a tree line on mountain slopes.


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Rocks and soil

In terrestrial environments, the pH, mineral composition, and physical structure of rocks and soil limit the distribution of plants and thus of the animals that feed on them, contributing to the patchiness of terrestrial ecosystems. The pH of soil can limit the distribution of organisms directly, through extreme acidic or basic conditions, or indirectly, by affecting the solubility of nutrients and toxins. In a river, the composition of the rocks and soil that make up the substrate (riverbed) can affect water chemistry, which in turn influences the resident organisms. In freshwater and marine environments, the structure of the substrate determines the organisms that can attach to it or burrow into it.

Test Your Understanding Answers Now you should be ready to test your knowledge. Place your answers here: 1. b

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Chapter 53: Population Ecology The next three chapters on population, community, and ecosystem ecology provide the academic backbone for this unit on ecology. Each chapter considers a different organizational level in ecology, starting with population ecology. Before beginning your study of each chapter, be sure you have a clear understanding of the in the chapter title. This chapter will help you master EK 4.A.5, Communities are composed of populations of organisms that interact in complex ways, and LOs 4.11, 4.12, and 4.13.. Concept 53.1 Biological processes influence population density, dispersion, and demographics 1. What two pieces of data are needed to mathematically determine density? The number of individuals and the unit area or volume are required to determine density mathematically. 2. What is the difference between density and dispersion? The density of a population is the number of individuals per unit area or volume—for example, the number of oak trees per square kilometer in Minnesota County or the number of Escherichia coli bacteria per milliliter in a test tube. Dispersion is the pattern of spacing among individuals within the boundaries of the population. 3. Work through Figure 53.2 in your text, doing the math to make sure you get the same answer as the text. Note and understand what the letters of the formula mean. Next, try the following problem. A population ecologist wished to determine the size of a population of white-footed deer mice, Peromyscus leucopus, in a 1-hectare field. Her first trapping yielded 80 mice, all of which were marked with a dab of purple hair dye on the back of the neck. Two weeks later, the trapping was repeated. This time 75 mice were trapped, out of which 48 of the mice were marked. Using the formula N = mn/x, what is the population of mice in the field? (Answer is at the end of this reading guide.) N = (80)(75)/48 or 125 mice/hectare 4. Explain the impact of immigration and emigration on population density. (To avoid confusion between these two , it might help to use this memory trick: immigration is the movement into a population, while emigration is the exiting of individuals from a population.) Density is not a static property but changes as individuals are added to or removed from a population (Figure 53.3). Additions occur through birth (which we define here to include all forms of reproduction) and immigration, the influx of new individuals from other areas. The factors that remove individuals from a population are death (mortality) and emigration, the movement of individuals out of a population and into other locations.


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5. Label the dispersion pattern shown by each population in the following figure. Second, and most important, what do the dispersion patterns tell us about the individuals in the population and their interactions? See page 1187 in your text for the labeled figure. The most common pattern of dispersion is clumped, in which individuals are aggregated in patches. Plants and fungi are often clumped where soil conditions and other environmental factors favor germination and growth. Mushrooms, for instance, may be clumped within and on top of a rotting log. Insects and salamanders may be clumped under the same log because of the higher humidity there. Clumping of animals may also be associated with mating behavior. Mayflies, which survive only a day or two as mating adults, often swarm in great numbers, a behavior that increases their chance of mating. Sea stars group together in tide pools, where food is readily available and where they can breed successfully (Figure 53.4a). Forming groups may also increase the effectiveness of predation or defense; for example, a wolf pack is more likely than a single wolf to subdue a moose, and a flock of birds is more likely than a single bird to warn of a potential attack. A uniform, or evenly spaced, pattern of dispersion may result from direct interactions between individuals in the population. Some plants secrete chemicals that inhibit the germination and growth of nearby individuals that could compete for resources. Animals often exhibit uniform dispersion as a result of antagonistic social interactions, such as territoriality—the defense of a bounded physical space against encroachment by other individuals (Figure 53.4b). Uniform patterns are rarer than clumped patterns. In random dispersion (unpredictable spacing), the position of each individual in a population is independent of other individuals. This pattern occurs in the absence of strong attractions or repulsions among individuals or where key physical or chemical factors are relatively constant across the study area. Plants established by windblown seeds, such as dandelions, may be randomly distributed in a fairly uniform habitat (Figure 53.4c). Random patterns are not as common in nature as one might expect; most populations show at least a tendency toward a clumped distribution. 6. In what population statistics do demographers have a particular interest? How are these data often presented? Of particular interest to demographers are birth rates and death rates. A useful way to summarize some of the vital statistics of a population is to make a life table. 7. Is your biology class a cohort? Explain. A cohort is a group of individuals of the same age. Most AP Biology classes are a cohort, but collegelevel biology classes may include a variety of ages and therefore not be a cohort. 8. Survivorship curves show patterns of survival. In general , survivorship curves can be classified into three types. Using the following figure, label and explain the three idealized survivorship patterns. See page 1188 in your text for the labeled figure.


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Although diverse, survivorship curves can be classified into three general types (Figure 53.6). A Type I curve is flat at the start, reflecting low death rates during early and middle life, and then drops steeply as death rates increase among older age groups. Many large mammals, including humans, produce few offspring but provide them with good care and exhibit this kind of curve. In contrast, a Type III curve drops sharply at the start, reflecting very high death rates for the young, but flattens out as death rates decline for those few individuals that survive the early period of die-off. This type of curve is usually associated with organisms that produce very large numbers of offspring but provide little or no care, such as long-lived plants, many fishes, and most marine invertebrates. An oyster, for example, may release millions of eggs, but most larvae hatched from fertilized eggs die from predation or other causes. Those few offspring that survive long enough to attach to a suitable substrate and begin growing a hard shell tend to survive for a relatively long time. Type II curves are intermediate, with a constant death rate over the organism’s life span. This kind of survivorship occurs in Belding’s ground squirrels (see Figure 53.5) and some other rodents, various invertebrates, some lizards, and some annual plants. Many species fall somewhere between these basic types of survivorship or show more complex patterns. In birds, mortality is often high among the youngest individuals (as in a Type III curve) but is fairly constant among adults (as in a Type II curve). Some invertebrates, such as crabs, may show a “stair-stepped” curve, with brief periods of increased mortality during molts, followed by periods of lower mortality when their protective exoskeleton is hard.

9. In the natural world, many species show survivorship curves that are combinations of the standard curves. How would an open nesting songbird’s survivorship curve appear if it was Type III for the first year and then Type II for the rest of its life span? Sketch this curve on the survivorship curve graph in question 8. The first part of this curve would fall sharply, like the blue line in the graph, then angle over like the black line to the far right corner of the graph. 10. What does a reproductive table show? A reproductive table, or fertility schedule, is an age-specific summary of the reproductive rates in a population. It is constructed by measuring the reproductive output of a cohort from birth until death. For a sexual species, the reproductive table tallies the number of female offspring produced by each age group. 11. Study Figure 53.7, then decide which breeding female turtle laid the eggs in nest #74. Justify your response. When the genetic profile of the eggshell sample #74 was compared to the breeding female #109, there was a match in the STR markers at 14 different loci, identifying the female that laid the eggs of that particular nest. Concept 53.2 The exponential model describes population growth in an idealized, unlimited environment


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Do not let the math in this section be a problem. Instead of trying to understand the calculus involved, concentrate on the idea of exponential growth, how it is graphed, and what this type of growth indicates about a population. 12. What is the advantage to using per capita birth and death rates rather than just the raw numbers of births and deaths? Using per capita birth rates allows for a comparison between populations; using just the number of births does not allow for comparisons. For example, a population of 10,000 would have a lot more births than one of 1,000 even if its per capita birth rate was much lower. 13. What will the per capita birth and death rates be if a population is demonstrating zero population growth? Zero population growth (ZPG) occurs when the per capita birth and death rates are equal (r = 0). Births and deaths still occur in such a population, of course, but they balance each other exactly. 14. What does it mean for a population to be in exponential population growth? Population increase under ideal conditions in a population whose all have access to abundant food and are free to reproduce at their physiological capacity is called exponential population growth, also known as geometric population growth. Under these conditions, the per capita rate of increase may assume the maximum rate for the species, denoted as rmax. The equation for exponential population growth is: dN/dt = r instN

The size of a population that is growing exponentially increases at a constant rate, resulting eventually in a J-shaped growth curve when population size is plotted over time. 15. In the following graph, explain why the line with the value of 1.0 shows a steeper slope that reaches exponential growth more quickly than does the line with the value of 0.5. On this graph, add a third line that approximates a population with an exponential value of 1.25. See page 1191 in your text for the labeled figure. The size of a population that is growing exponentially increases at a constant rate, resulting eventually in a J-shaped growth curve when population size is plotted over time (Figure 53.7). Although the maximum rate of increase is constant, the population accumulates more new individuals per unit of time when it is large than when it is small; thus, the curves in Figure 53.7 get progressively steeper over time. This occurs because population growth depends on N as well as rmax, and larger populations experience more births (and deaths) than small ones growing at the same per capita rate. It is also clear from Figure 53.7 that a population with a higher maximum rate of increase (dN/dt = 1.0N) will grow faster than one with a lower rate of increase (dN/dt = 0.5N). The line for an rmax of 1.25 would be between the blue line and the y-axis, rising even steeper than the blue 1.0 value. 16. What are two examples of conditions that might lead to exponential population growth in natural populations? Copyright © 2015 Pearson Education, Inc.

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The J-shaped curve of exponential growth is characteristic of some populations that are introduced into a new environment or whose numbers have been drastically reduced by a catastrophic event and are rebounding. Concept 53.3 The logistic model describes how a population grows more slowly as it nears its carrying capacity 17. What is carrying capacity? Ecologists define carrying capacity, symbolized by K, as the maximum population size that a particular environment can sustain. Carrying capacity varies over space and time with the abundance of limiting resources. 18. What are six examples of limiting resources that can influence carrying capacity? Energy, shelter, refuge from predators, nutrient availability, water, and suitable nesting sites can all be limiting factors. 19. In the logistic population growth model, the per capita rate of increase approaches zero as the carrying capacity is reached. 20. If the carrying capacity (or K) is 1,000 and N is 10, the term (K – N)/K is large. Explain why a large value for (K – N)/K predicts growth close to the maximum rate of increase for this population. A large value for (K – N)/K predicts growth close to the maximum rate of increase for this population because there is lots of available space and other resources in the environment. The population growth rate decreases dramatically as N approaches K. 21. In the following graph, explain why the logistic model predicts a sigmoid (S-shaped) growth curve when the population density is plotted over time. Hint: The critical part of this answer concerns why growth slows as N approaches K. See page 1193 in your text for the labeled figure. New individuals are added to the population most rapidly at intermediate population sizes, when there is not only a breeding population of substantial size but also lots of available space and other resources in the environment. The population growth rate decreases dramatically as N approaches K. For a population’s growth rate to decrease, the birth rate, b, must decrease, the death rate, m, must increase, or both. Factors affecting these rates include the presence of disease, predation, and limited amounts of food and other resources. Concept 53.4 Life history traits are products of natural selection 22. On what is the life history of an organism based? The traits that affect an organism’s schedule of reproduction and survival make up its life history.


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23. What three variables form the life history of a species? A life history entails three main variables: when reproduction begins (the age at first reproduction or age at maturity), how often the organism reproduces, and how many offspring are produced per reproductive episode. 24. Explain the difference between semelparity (big-bang reproduction) and iteroparity (repeated reproduction) as life history strategies. In semelparity, organisms produce many offspring all at once to increase the probability that at least some of those offspring will survive. In contrast to semelparity is iteroparity (from the Latin iterare, “to repeat”), or repeated reproduction. In iteroparity, organisms produce relatively few but large offspring each time they reproduce, and they provision the offspring better. 25. Explain how two critical factors influence whether a species will evolve toward semelparity or iteroparity. A current hypothesis suggests that there are two critical factors: the survival rate of the offspring and the likelihood that the adult will survive to reproduce again. Where the survival rate of offspring is low, typically in highly variable or unpredictable environments, the prediction is that semelparity will be favored. Adults are also less likely to survive in such environments, so producing large numbers of offspring should increase the probability that at least some of those offspring will survive. Iteroparity may be favored in more dependable environments, where adults are more likely to survive to breed again and where competition for resources may be intense. In such cases, a few, relatively large, wellprovisioned offspring should have a better chance of surviving until they can reproduce. 26. Refer to Figure 53.14 to explain the effect of offspring care on parental survival in kestrels. A study of European kestrels demonstrated a survival cost to parents that care for a large number of young. The lower survival rates of kestrels with larger broods indicate that caring for more offspring negatively affects survival of the parents. 27. The end of this concept attempts to bring together the ideas of life histories and growth models. This is done with the introduction of two new : K-selection and r-selection. Explain the ideas behind the creation of these two . Selection for traits that are sensitive to population density and are favored at high densities is known as K-selection, or density-dependent selection. In contrast, selection for traits that maximize reproductive success in uncrowded environments (low densities) is called r-selection, or density-independent selection. These names follow from the variables of the logistic equation. K-selection is said to operate in populations living at a density near the limit imposed by their resources (the carrying capacity, K), where competition among individuals is stronger. Mature trees growing in an old-growth forest are an example of K-selected organisms. In contrast, r-selection is said to maximize r, the per capita rate of increase, and occurs in environments in which population densities are well below carrying capacity or individuals face little competition. Copyright © 2015 Pearson Education, Inc.

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Concept 53.5 Many factors that regulate population growth are density dependent 28. Compare and contrast these two : density-independent regulation: A birth rate or death rate that does not change with population density is said to be density independent. density-dependent regulation: In contrast, a death rate that rises as population density rises is said to be density dependent, as is a birth rate that falls with rising density. 29. Explain how negative plays an essential role in the unifying theme of regulation of populations. Does negative play a role in both density-independent and density-dependent regulation? Biology’s unifying theme of regulation (see Chapter 1) applies to population dynamics. Without some type of negative between population density and the rates of birth and death, a population would never stop growing. Density regulation provides that , halting population growth through mechanisms that reduce birth rates or increase death rates. 30. Complete the following chart.

Density-Dependent Population Regulation

k Mechanism ources

Explanation Increasing population density intensifies competition for nutrients and other resources, reducing reproductive rates.

If the transmission rate of a particular disease depends on a certain level of crowding in a population, then the disease’s impact is density dependent.


Example Farmers minimize the effect of resource competition on the growth of grains such as wheat (Triticum aestivum) and other crops by applying fertilizers to reduce nutrient limitations on crop yield. In humans, respiratory diseases such as influenza (flu) and tuberculosis are caused by pathogens that spread through the air when an infected person sneezes or coughs. Both diseases strike a greater percentage of people in densely populated cities than in rural areas.

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Predation can be an important cause of density-dependent mortality if a predator captures more food as the population density of the prey increases. As a prey population builds up, predators may also feed preferentially on that species. Intrinsic physiological factors sometimes regulate population size.

Territoriality can limit population density when space becomes the resource for which individuals compete. Maintaining a territory increases the likelihood that an animal will capture enough food to reproduce. The presence of surplus, or nonbreeding, individuals is a good indication that territoriality is restricting population growth.

Some fish species, such as the cutthroat trout (Oncorhynchus clarkii), concentrate for a few days on a particular insect species that is emerging from its aquatic larval stage and then switch to another prey species when it becomes more abundant. Reproductive rates of whitefooted mice (Peromyscus leucopus) in a field enclosure can drop even when food and shelter are abundant. This drop in reproduction at high population density is associated with aggressive interactions and hormonal changes that delay sexual maturation and depress the immune system. In this species, high density causes a decrease in the birth rate and an increase in the death rate. Cheetahs (Acinonyx jubatus) use a chemical marker in urine to warn other cheetahs of their territorial boundaries. Australasian gannets (Morus serrator) defend their territories when nesting by calling and pecking at one another.

Yeasts, such as the brewer’s yeast Saccharomyces cerevisiae, are used to convert carbohydrates to ethanol in wine making. The ethanol that accumulates in the wine is toxic to yeasts and contributes to density-dependent regulation of yeast population size. The alcohol content of wine is usually less than 13% because that is the maximum concentration of ethanol that most wineproducing yeast cells can Copyright © 2015 Pearson Education, Inc.

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tolerate.

31. Explain the population dynamics. Resulting from both biotic and abiotic factors that for the fluctuations in the moose population on Isle Royale over the last 50 years. The moose population has experienced two major increases and collapses during the last 50 years. The first collapse was driven by a peak in the number of wolves on Isle Royale (density-dependent regulation), whereas the second collapse coincided with harsh winter weather (density-independent factor). 32. Explain the importance of immigration and emigration in metapopulations. Immigration and emigration are particularly important when a number of local populations are linked, forming a metapopulation. Local populations in a metapopulation can be thought of as occupying discrete patches of suitable habitat in a sea of otherwise unsuitable habitat. Such patches vary in size, quality, and isolation from other patches, factors that influence how many individuals move among the populations. Patches with many individuals can supply more emigrants to other patches. If one population becomes extinct, the patch it occupied can be recolonized by immigrants from another population. The metapopulation concept underscores the significance of immigration and emigration in the butterfly populations. It also helps ecologists understand population dynamics and gene flow in patchy habitats, providing a framework for the conservation of species living in a network of habitat fragments and reserves. Concept 53.6 The human population is no longer growing exponentially but is still increasing rapidly 33. Summarize human population growth since 1650. (Of all the reported statistics, which one surprises you the most?) The exponential growth model in Figure 53.7 approximates the human population explosion over the last four centuries (Figure 53.22). Ours is a singular case; no other population of large animals has likely ever sustained so much growth for so long. The human population increased relatively slowly until about 1650, at which time approximately 500 million people inhabited Earth. Our population Copyright © 2015 Pearson Education, Inc.

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doubled to 1 billion within the next two centuries, doubled again to 2 billion by 1930, and doubled still again by 1975 to more than 4 billion. The global population is now more than 6.8 billion people and is increasing by about 79 million each year. Currently the population grows by more than 200,000 people each day, the equivalent of adding a city the size of Amarillo, Texas, or Kitchener, Ontario. At this rate, it takes only about four years to add the equivalent of another United States to the world population. Population ecologists predict a population of 7.8–10.8 billion people on Earth by the year 2050. Although the global population is still growing, the rate of growth did begin to slow during the 1960s (Figure 53.23). The annual rate of increase in the global population peaked at 2.2% in 1962; by 2009, it had declined to 1.2%. Current models project a continued decline in the annual growth rate to roughly 0.5% by 2050, a rate that would still add 45 million more people per year if the population climbs to a projected 9 billion. The reduction in growth rate over the past four decades shows that the human population has departed from true exponential growth, which assumes a constant rate. This departure is the result of fundamental changes in population dynamics due to diseases, including AIDS, and to voluntary population control. 34. What is demographic transition? In demographic transition which falls first, birth or death rates? The movement from high birth and death rates toward low birth and death rates, which tends to accompany industrialization and improved living conditions, is called the demographic transition. Death rates fall before birth rates, often by many years (150 years in Sweden). 35. You should be able to look at age-structure graphs and make predictions about the future growth of the population. Using Figure 53.24 in your text, describe the key features for the three age-structure graphs and predict how the population of each country will grow. Country Afghanistan

Key Features The pyramid is bottom-heavy, skewed toward young individuals.


Predicted Future Growth Young individuals will grow up and perhaps sustain the explosive growth with their own reproduction.

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United States

The age structure for the United States is relatively even until the older, postreproductive ages, except for a bulge that corresponds to the “baby boom” that lasted for about two decades after the end of World War II.

Italy

For Italy, the pyramid has a small base, indicating that individuals younger than reproductive age are relatively underrepresented in the population.

Even though couples born during the decades after World War II have had an average of fewer than two children, the nation’s overall birth rate still exceeds the death rate because some “boomers” and most of the boomers’ offspring are still of reproductive age. Moreover, although the current total reproductive rate in the United States is 2.1 children per woman—approximately replacement rate—the population is projected to grow slowly through 2050 as a result of immigration. This situation contributes to the projection of a population decrease in Italy.

36. Why do infant mortality and life expectancy vary so greatly between certain countries? Infant mortality, the number of infant deaths per 1,000 live births, and life expectancy at birth, the predicted average length of life at birth, vary widely among different human populations. Although global life expectancy has been increasing since about 1950, it has recently dropped in a number of regions, including countries of the former Soviet Union and in sub-Saharan Africa. In these regions, social upheaval, decaying infrastructure, and infectious diseases such as AIDS and tuberculosis are reducing life expectancy. 37. Can the world’s population sustain an ecological footprint that is currently the average American footprint? Explain. No. The ecological footprint concept summarizes the aggregate land and water area required by each person, city, or nation to produce all the resources it consumes and to absorb all the waste it generates. One way to estimate the ecological footprint of the entire human population is to add up all the ecologically productive land on the planet and divide by the population. This calculation yields approximately 2 hectares (ha) per person (1 ha = 2.47 acres). Reserving some land for parks and conservation means reducing this allotment to 1.7 ha per person—the benchmark for comparing actual ecological footprints. Anyone who consumes resources that require more than 1.7 ha to produce is said to be using an unsustainable share of Earth’s resources. A typical ecological footprint for a person in the United States is about 10 ha. Test Your Understanding Answers Now you should be ready to test your knowledge. Place your answers here: Copyright © 2015 Pearson Education, Inc.

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1. b 2. a 3. a 4. d 5. c 6. b 7. c Answer to Question 3: 125 P. leucopus


8. d

9. a

10. a

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Name _______________________ Period ___________

Chapter 54: Community Ecology This chapter focuses on interactions at the community level, and will take you through concepts that you have studied before as well as introduce you to new and interesting ideas such as island biogeography, keystone species, and diversity indexes. EK 4.B.3, Interactions between and within populations influence patterns of species distribution and abundance, and EK 4.C.4, The diversity of species within an ecosystem may influence the stability of the ecosystem, are specifically addressed in this chapter. Concept 54.1 Community interactions are classified by whether they help, harm, or have no effect on the species involved. 1. What is a community? A community is a group of populations of different species living close enough to interact. 2. This section will look at interspecific interactions. Be clear on the meaning of the prefix! To begin, distinguish between intraspecific competition and interspecific competition. Give an example of each. Type of Competition Intraspecific competition

Interspecific competition

Explanation Example Intraspecific competition is competition Answers may vary. An example between of the same species. would be the competition between two male cardinals for a mate, or between two dogs for a meaty bone. Interspecific competition is competition Weeds growing in a garden between of different species for the compete with garden plants for same resource. soil nutrients and water. Grasshoppers and bison in the Great Plains compete for the grass they both eat. Lynx and foxes in the northern forests of Alaska and Canada compete for prey such as snowshoe hares.

3. What is G. F. Gause’s competitive exclusion principle? Give one example. G. F. Gause’s competitive exclusion principle holds that two species competing for the same limiting resources cannot coexist permanently in the same place. In the absence of disturbance, one species will use the resources more efficiently and reproduce more rapidly than the other. Even a slight reproductive advantage will eventually lead to local elimination of the inferior competitor, an outcome called competitive exclusion.


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Gause studied this question using laboratory experiments with two closely related species of ciliated protists, Paramecium aurelia and Paramecium caudatum. He cultured the species under stable conditions, adding a constant amount of food each day. When Gause grew the two species together, P. caudatum became extinct in the culture. Gause inferred that P. aurelia had a competitive edge in obtaining food. 4. Define ecological niche. The sum of a species’ use of the biotic and abiotic resources in its environment is called its ecological niche. 5. Several species of Anolis lizards live in the same types of trees and have a similar diet. Discuss resource partitioning to explain how interspecific competition is reduced. (Study Figure 54.2 in your text.) Seven species of Anolis lizards live in close proximity, and all feed on insects and other small arthropods. However, competition for food is reduced because each lizard species has a different preferred perch, thus occupying a distinct niche. 6. What is the difference between the fundamental niche and the realized niche? A species’ fundamental niche is the niche potentially occupied by that species. A species’ fundamental niche is often different from its realized niche, the portion of its fundamental niche that it actually occupies in a particular environment. This difference is a result of competition. 7. Use Inquiry Figure 54.3 to determine the realized and fundamental niche of the two barnacle species. If Balanus has a fundamental niche that is equal to its realized niche, use arrows to show the area both species would cover for both types of niches. Your diagram will have a fundamental and realized arrow to show both niche types for both species. See page 1210 for the labeled figure. 8. Study Figure 54.4 in your text, and then explain what is meant by character displacement. (To do this, you will have to learn or review the difference between sympatric populations and allopatric populations. You will find this information in Chapter 24.) Sympatric populations (geographically overlapping), which would potentially compete for resources, show differences in body structures and in the resources they use. This tendency for characteristics to diverge more in sympatric than in allopatric populations of two species is called character displacement. The Galápagos finches shown in Figure 54.4 show character displacement. You see this in the bottom graph, where the two species of finches have very different average beak sizes when they are sympatric. 9. How does character displacement reduce interspecific competition? In your explanation, describe the role of natural selection in character displacement. In sympatric populations where two species are competing for similar resources, character displacement leads to divergence in morphological traits so that the species can occupy different niches. In this context, natural selection is the mechanism of character displacement as the two populations diverge in Copyright © 2015 Pearson Education, Inc.

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phenotype (beak size, for example) and no longer have overlapping niches. See Figure 54.4 for a good illustration of this in species of Galapagos finches. 10. Predation is a term that you probably already know. Can you give examples of some predator-prey combinations as listed in the following chart? Predator Animal Animal Fungus Bacteria Fungus

Prey Animal Plant Animal Animal Plant

Example A tick on a human A grasshopper eating oak leaves Athlete’s foot fungus on a human A human with a staph infection A rose plant with powdery mildew

11. List three special adaptations that some predator species possess for obtaining food. Special adaptations that predator species possess for obtaining food include acute senses that enable them to find and identify potential prey; adaptations like claws, teeth, fangs, stingers, and poison that help them capture and subdue their food; and mimicry that allows them to entice their prey (as in the case of the alligator snapping turtle whose tongue resembles a worm and can attract fish). 12. List three ways prey species might elude predators. Prey species elude predators through behavioral defenses (hiding, fleeing, forming herds or schools; sometimes active self-defense and alarm calls). Prey species also display a variety of morphological and physiological defensive adaptations such as cryptic coloration (camouflage), and mechanical or chemical defenses (for example, those used by porcupines, skunks, and the toxic European fire salamander). Animals with effective chemical defenses often exhibit bright aposematic coloration, or warning colors. Some prey species are protected by their resemblance to other species. 13. Compare the two types of mimicry. Type of Mimicry Batesian

Description In Batesian mimicry, a palatable or harmless species mimics an unpalatable or harmful one.


Example The larva of the hawkmoth Hemeroplanes ornatus puffs up its head and thorax when disturbed, looking like the head of a small poisonous snake. In this case, the mimicry even involves behavior; the larva weaves its head back and forth and hisses like a snake.

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Müllerian

In Müllerian mimicry, two or more unpalatable species resemble each other. Presumably, the more unpalatable prey are, the more quickly predators learn to avoid prey with that particular coloration. The shared appearance thus becomes a kind of aposematic coloration.

The cuckoo bee and the yellow jacket are two unpalatable species that resemble one another. In an example of convergent evolution, unpalatable animals in several different taxa have similar patterns of coloration: Black and yellow or red stripes characterize unpalatable animals as diverse as yellow jackets and coral snakes.

14. What is herbivory? Ecologists use the term herbivory to refer to a +/– interaction in which an organism eats parts of a plant or alga. 15. Did you list any special herbivore adaptations for predation in your response to question 10? Or plant adaptations to avoid herbivory? List two adaptations for each category here. Some insects have chemical sensors on their feet that enable them to distinguish between toxic and nontoxic plants as well as between more nutritious and less nutritious plants. Some mammalian herbivores, such as goats, use their sense of smell to examine plants, rejecting some and eating others. They may also eat just a specific part of a plant, such as the flowers. A plant’s arsenal against herbivores may feature chemical toxins or structures such as spines and thorns. Among the plant compounds that serve as chemical weapons are the poison strychnine, produced by the tropical vine Strychnos toxifera; nicotine, from the tobacco plant; and tannins, from a variety of plant species. Plants in the genus Astragalus accumulate selenium; they are known as “locoweeds” because the cattle and sheep that eat them wander aimlessly in circles and may even die. Compounds that are not toxic to humans but may be distasteful to many herbivores are responsible for the familiar flavors of cinnamon, cloves, and peppermint. Certain plants produce chemicals that cause abnormal development in some insects that eat them. 16. Describe and give an example of each of the following interactions: Type of Interaction Symbiosis

Description

Example

When individuals of two or more species live The examples below are all considered in direct and intimate with one another, symbiosis in this text. their relationship is called symbiosis.


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Parasitism

Parasitism is a +/– symbiotic interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process.

Mutualism

Mutualistic symbiosis, or mutualism, is an interspecific interaction that benefits both species (+/+).

Commensalism

An interaction between species that benefits one of the species but neither harms nor helps the other (+/0) is called commensalism.

Parasites that live within the body of their host, such as tapeworms, are called endoparasites; parasites that feed on the external surface of a host, such as ticks and lice, are called ectoparasites. We have described many examples of mutualism in previous chapters: nitrogen fixation by bacteria in the root nodules of legumes; the digestion of cellulose by microorganisms in the digestive systems of termites and ruminant mammals; the exchange of nutrients in mycorrhizae, associations of fungi, and the roots of plants; and photosynthesis by unicellular algae in corals. The interaction between termites and the microorganisms in their digestive system is an example of obligate mutualism, in which at least one species has lost the ability to survive without its partner. In facultative mutualism, both species can survive alone. “Hitchhiking” species, such as algae that live on the shells of aquatic turtles or barnacles that attach to whales, are sometimes considered commensal. The hitchhikers gain a place to grow while having seemingly little effect on their ride. However, the hitchhikers may in fact slightly decrease the reproductive success of their hosts by reducing the hosts’ efficiency of movement in searching for food or escaping from predators. Conversely, the hitchhikers may provide a benefit in the form of camouflage.

17. Which category in the previous chart includes the other three? Note that other texts may define this term more narrowly. This book adopts a general definition of symbiosis that includes all such interactions, whether they are harmful, helpful, or neutral. Some biologists define symbiosis more narrowly as a synonym for mutualism, an interaction in which both species benefit. Copyright © 2015 Pearson Education, Inc.

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18. Your text uses +/–/0 symbols to indicate how interspecific interactions affect survival and reproduction of the two species. Use this notation for each of these interactions. Type of Interaction

+/+, +/–, –/–, +/0

Predation

– /+

Commensalism

+/0

Mutualism

+/+

Parasitism

+/–

Interspecific competition –/– Herbivory

+/–

Concept 54.2 Diversity and trophic structure characterize biological communities 19. What is species diversity? What are its two components? Why is it important? The species diversity of a community—the variety of different kinds of organisms that make up the community—has two components. One is species richness, the number of different species in the community. The other is the relative abundance of the different species, the proportion each species represents of all individuals in the community. 20. Your text works a simple Shannon diversity index to demonstrate that community 1 is more diverse than community 2. Looking at the formula and what determines species diversity, explain why community 1 is more diverse. Species diversity has two components—species richness, or number of different species in the community, and relative abundance, or the proportion each species represents of all individuals in the community. Although community 1 and 2 both have the same species richness, 80% of community 2 is made up of species A, whereas community 1 has a more evenly distributed relative abundance, with 25% of the total number of individuals represented by each species in the community. 21. What does an ecologist summarize in a food web? Ecologists summarize the trophic relationships of a community by diagramming a food web with arrows linking species according to who eats whom. 22. Know the levels of trophic structure in food chains. Give an example food chain here, including four links that might be found in a prairie community, and tell the trophic level for each organism. The structure and dynamics of a community depend on the feeding relationships between organisms— the trophic structure of the community. The transfer of food energy up the trophic levels from its source in plants and other autotrophic organisms (primary producers) through herbivores (primary consumers) Copyright © 2015 Pearson Education, Inc.

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to carnivores (secondary, tertiary, and quaternary consumers) and eventually to decomposers is referred to as a food chain. Grass  grasshoppers  mouse  hawk The grass is a producer, the grasshoppers are first-order consumers, the mouse is a second-order consumer, and the hawk is a third-order consumer. 23. According to the energetic hypothesis, why are food chains limited in length? How much energy is typically transferred to each higher level? The energetic hypothesis suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain. Only about 10% of the energy stored in the organic matter of each trophic level is converted to organic matter at the next trophic level. 24. What is a dominant species? For the area where you live, what would be considered a dominant tree species? Dominant species in a community are the species that are the most abundant or that collectively have the highest biomass. As a result, dominant species exert a powerful control over the occurrence and distribution of other species. Typical examples would be the oak or maple in the East. In other regions, individual teachers will know the dominant species! 25. How is a keystone species different from a dominant species? A keystone species exerts strong control on community structure not by numerical might but by its pivotal ecological role, or niche. When a keystone species is lost, the ecological effect is much broader than the loss of a single link in a food chain. 26. Name one keystone species, and explain the effect its removal has on the ecosystem. The sea otter, a keystone predator in the North Pacific, is a keystone species. Sea otters feed on sea urchins, and sea urchins feed mainly on kelp. In areas where sea otters are abundant, sea urchins are rare and kelp forests are well developed. Where sea otters are rare, sea urchins are common and kelp is almost absent. Over the last 20 years, orcas have been preying on sea otters as the orcas’ usual prey has declined. As a result, sea otter populations have plummeted in large areas off the coast of western Alaska, sometimes at rates as high as 25% per year. The loss of this keystone species has allowed sea urchin populations to increase, resulting in the loss of kelp forests. Concept 54.3 Disturbance influences species diversity and composition 27. What is the intermediate disturbance hypothesis? Give an example of a disturbance event, and explain the effect it has on the community.


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The intermediate disturbance hypothesis states that moderate levels of disturbance foster greater species diversity than do low or high levels of disturbance. A prairie fire is an example of a disturbance event. It would remove some of the woody brush, leaving the deep-rooted plants intact. They would then sprout with less competition for water and light. 28. Ecological succession is the changes in species that occupy an area after a disturbance. What is the difference between primary succession and secondary succession? Primary succession occurs where the disturbance leaves an area without soil. Soil develops gradually as rocks weather and organic matter accumulates from the decomposed remains of the early colonizers. An example of primary succession would be the events after volcanic flow. Secondary succession occurs when an existing community has been cleared by some disturbance that leaves the soil intact, as in Yellowstone following the 1988 fires, or after clearcutting of a forest. Concept 54.4 Biogeographic factors affect community diversity 29. Explain latitudinal gradients in of species richness. Where is species richness greatest? Species richness is greatest in the latitudes nearer the equator. As one progresses further from the equator, the species richness declines. 30. There are probably two key factors in latitudinal gradients. List and explain both here, and put a star next to the one that is probably the primary cause of the latitudinal difference in biodiversity. *One factor for greater species richness nearer the equator is the climate, including a longer growing season. Another key factor leading to greater species richness nearer the equator is that the equatorial communities are often older, allowing more time for speciation. Climate is likely the primary cause of the latitudinal gradient in richness and diversity. 31. Evapotranspiration is a function of light, temperature, and water and is highest in areas that have high temperatures and rainfall. Explain in of energy budgets why areas with high evapotranspiration tend to have the greatest species richness. In areas with high energy budgets, more free energy is available for primary production, thus providing more niche opportunities for a greater number of species, as opposed to an area with a low energy budget, where competition for resources would be more intense. Over the course of evolutionary time, species richness may increase in a community as more speciation events occur. Tropical communities are generally older than temperate or polar communities, which have repeatedly “started over” after major disturbances from glaciations. Also, the growing season in tropical forests is about five times as long as in tundra communities of high latitudes. In effect, biological time runs about five times as fast in the tropics as near the poles, so intervals between speciation events are shorter in the tropics. Copyright © 2015 Pearson Education, Inc.

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32. Explain what is demonstrated by a species-area curve. All other factors being equal, the larger the geographic area of a community, the more species it has. The likely explanation for this pattern is that larger areas offer a greater diversity of habitats and microhabitats than smaller areas. 33. Use species-area curves to predict the effect that habitat fragmentation has on extinction rates. Justify your prediction. Considering that the larger the geographic area of a community, the more species it has, one could logically predict that habitat fragmentation would increase extinction rates because the community’s geographic area is being reduced by habitat fragmentation. 34. Renowned American ecologists Robert MacArthur and E. O. Wilson developed a model of island biogeography. Although the model can be demonstrated with islands, any isolated habitat represents an island. What are the two factors that determine the number of species on the island? Two factors that determine the number of species on the island are the rate at which new species immigrate to the island and the rate at which species become extinct on the island. 35. What two physical features of the island affect immigration and extinction rates? Two physical features of the island further affect immigration and extinction rates: its size and its distance from the mainland. 36. Why do small islands have lower immigration rates? Why do they have higher extinction rates? Small islands generally have lower immigration rates because potential colonizers are less likely to reach a small island. Small islands also have higher extinction rates because they generally contain fewer resources, have less diverse habitats, and have smaller population sizes. 37. Closer islands have lower extinction rates and higher immigration rates. 38. What is the island equilibrium model? In the 1960s, American ecologists Robert MacArthur and E. O. Wilson developed a general model of island biogeography, identifying the key determinants of species diversity on an island with a given set of physical characteristics. MacArthur and Wilson’s model is called the island equilibrium model because equilibrium will eventually be reached where the rate of species immigration equals the rate of species extinction. The number of species at this equilibrium point is correlated with the island’s size and distance from the mainland. 39. The equilibrium number of species on an island represents a balance between the immigration of new species and the extinction of species already there. This graph illustrates the equilibrium point between immigration and extinction on an island. Draw lines to show what would happen if the distance from the mainland doubled. Add an arrow to indicate the new equilibrium point. Justify your response.


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The new equilibrium number of species would be lower on this graph if the distance from the mainland doubled. The line that represent the changes in immigration rate for the increase in island distance will shift to a lower position on the y-axis because a closer island generally has a higher immigration rate than one farther away. Because of their higher immigration rates, closer islands tend to have lower extinction rates, as arriving colonizers help sustain the presence of a species on a near island and prevent its extinction. Concept 54.5 Pathogens alter community structure locally and globally 40. What is a pathogen? Pathogens are disease-causing microorganisms, viruses, viroids, or prions. 41. What is a zoonotic pathogen? List two examples. Zoonotic pathogens are defined as those that are transferred to humans from other animals, either through direct with an infected animal or by means of an intermediate species, called a vector. 42. What is a vector? List three examples. A vector is an agent used to spread or disperse something. The vectors that spread zoonotic diseases are often parasites, including ticks, lice, and mosquitoes. Test Your Understanding Answers Now you should be ready to test your knowledge. Place your answers here: 1. d

2. c

3. c

4. c

5. b

6. c


7. d

8. b

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Name _______________________ Period ___________

Chapter 55: Ecosystems and Restoration Ecology this: Energy flows, and chemicals cycle! For most ecosystems, energy comes from the sun, and is lost at every conversion. Productivity is an important topic to study. Be sure you have a firm grasp on photosynthesis and cellular respiration and understand energy flow through an ecosystem. The final concept is important for its look at human impact on ecosystems and how ecological damage is being remediated. Overview: 1. What is an ecosystem? An ecosystem is the sum of all the organisms living in a given area and the abiotic factors with which they interact. 2. Where does energy enter most ecosystems? How is it converted to chemical energy and then ed through the ecosystem? How is it lost? this: Energy cannot be recycled. Energy enters most ecosystems as sunlight. It is converted to chemical energy by autotrophs, ed to heterotrophs in the organic compounds of food, and dissipated as heat. 3. Besides the energy flow that you described in question 2, chemicals such as carbon and nitrogen cycle through ecosystems. So energy flows through an ecosystem and matter cycles within and through them. 4. It seems amazing, but how did the introduction of foxes onto arctic islands convert grassland to tundra? The foxes preyed upon seabirds, reducing their density almost 100-fold. Fewer birds meant less guano, the primary source of nutrients for the plants on the islands. The reduction in nutrient availability in turn favored slower-growing forbs and shrubs typical of tundra instead of grasses, which require more nutrients. Concept 55.1 Physical laws govern energy flow and chemical cycling in ecosystems 5. Both energy and matter can be neither created nor destroyed. 6. We can measure the efficiency of energy conversion in an ecosystem, as well as whether a given nutrient is being gained or lost from an ecosystem. Let us take a second look at trophic levels. What trophic level s all others? Autotrophs or primary producers 7. List three groups of organisms that are photosynthetic autotrophs. Plants, algae, and photosynthetic prokaryotes


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8. This concept reviews trophic relationships. Know all in your textbook that are bolded. What are trophic levels? What is always at the first trophic level? Trophic levels are feeding levels. Autotrophs are always at the first trophic level. 9. What are detritivores? What is their importance in chemical cycling? Detritivores are decomposers that eat nonliving organic material. Detritivores play a critical role in recycling chemical elements back to primary producers. Detritivores convert organic material from all trophic levels to inorganic compounds usable by primary producers, closing the loop of an ecosystem’s chemical cycling. 10. What are the two main categories of detritivores? Two important groups of detritivores are prokaryotes and fungi. 11. To reemphasize the idea that energy flows through ecosystems whereas nutrients cycle, label the following figure. See page 1235 for the labeled figure. Concept 55.2 Energy and other limiting factors control primary production in ecosystems 12. What is primary production? Distinguish between gross primary production and net primary production. Primary production is the amount of light energy converted into chemical energy—in the form of organic compounds—by autotrophs during a given time period. Gross primary production (GPP) is the total primary production in an ecosystem—the amount of energy from light (or chemicals, in chemoautotrophic systems) converted to the chemical energy of organic molecules per unit of time. Not all of this production is stored as organic material in the primary producers because they use some of the molecules as fuel in their own cellular respiration. Net primary production (NPP) is equal to gross primary production minus the energy used by the primary producers for their “autotrophic respiration.” 13. Write an equation here that shows the relationship between gross and net primary production. NPP = GPP – Ra 14. You may recall from Chapter 54 that biomass is the total mass of all individuals in a trophic level. Another way of defining net primary production is as the amount of new biomass added in a given period of time. Why is net primary production, or the amount of new biomass/unit of time, the key measurement to ecologists? To ecologists, net primary production is the key measurement because it represents the storage of chemical energy that will be available to consumers in the ecosystem.


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15. Which ecosystem would tend to have a greater biomass/unit area, a prairie or a tropical rain forest? Explain. The tropical rain forest will have the greater biomass/unit area. The rate of photosynthesis will be higher due to more light and available water. 16. Net primary productivity is the amount of new biomass/unit of time, and is the result of photosynthesis. To understand what can affect productivity, begin by writing the summary equation for photosynthesis. 6 CO2 + 6 H2O  C6H12O6 + 6 O2 17. As you look at the equation for photosynthesis, note that you could measure the rate of photosynthesis, and therefore indirectly measure productivity, in several ways. List them here. Oxygen production and/or consumption or carbon dioxide production and/or consumption 18. What are some factors that limit primary productivity in aquatic ecosystems? Light limitation and nutrient limitation are factors that limit primary productivity in aquatic ecosystems. 19. What is a limiting nutrient? What is the limiting nutrient off the shore of Long Island, New York? What is the limiting nutrient in the Sargasso Sea? Note that the limiting nutrient is always the one that, when added, results in increased productivity. A limiting nutrient is an element that must be added for production to increase. The limiting nutrient off the shore of Long Island, New York, is nitrogen. The limiting unit in the Sargasso Sea is the micronutrient iron. 20. Phytoplankton growth can be increased by additional nitrates and phosphates. What are common sources of each of these? Sewage and fertilizer runoff from farms and lawns are a common source of additional nutrients. 21. What is eutrophication? What are factors that contribute to eutrophication? Eutrophication is where a body of water receives excess nutrients that enhance algal and bacterial growth. Although the algae, for example, are photosynthesizing and putting oxygen into the water, they are also respiring, and as they die, the process of decomposition also results in reduced oxygen. This ultimately reduces the oxygen content and clarity of the water. Sewage and fertilizer runoff from farms and lawns contribute to eutrophication. Concept 55.3 Energy transfer between trophic levels is typically only 10% efficient 22. What is trophic efficiency? Trophic efficiency is the percentage of production transferred from one trophic level to the next.


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23. Generally, what percentage of energy available at one trophic level is available at the next? 10%

This is important! it.

24. Consider a food chain with 1,000 joules (an energy unit) available at the producer level. If this food chain is grass  grasshopper  lizard  crow, how much energy is found at the level of the crow? (See answer at the end of this Reading Guide chapter.) Show your work here. Grass (1,000 J)  grasshopper (100 J)  lizard (10 J)  crow (1 J) 25. Notice that most biomass pyramids have the greatest biomass on the bottom of the pyramid. Label the trophic levels on both of the following figures. Explain why the second pyramid of biomass is inverted. See page 1241 of your text for the labeled figure. The second pyramid of biomass is inverted because certain aquatic ecosystems have inverted biomass pyramids: Primary consumers outweigh the producers. Such inverted biomass pyramids occur because the producers—phytoplankton—grow, reproduce, and are consumed so quickly by the zooplankton that they never develop a large population size, or standing crop. In other words, the phytoplankton have a short turnover time, which means they have a small standing crop compared to their production. Because the phytoplankton continually replace their biomass at such a rapid rate, they can a biomass of zooplankton bigger than their own biomass. Nevertheless, because phytoplankton have much higher production than zooplankton, the pyramid of production for this ecosystem is still bottomheavy. 26. Why do people who have limited diets in overpopulated parts of the world eat low on the food chain? When humans consume rice and beans, for example, they are primary consumers, and about 10% of available energy is transferred to them. When humans consume meat, they are secondary consumers, and only about 1% of available energy is transferred to them. Consider the production of 100 hectares—if people eat the plant material rather than meat, there will be 10 times more energy (calories) available. 27. The Making Connections Figure 55.13 is an excellent way to review some of the basic ideas from the central core of ecology. After reviewing the figure, why do you think the tundra is considered an ecosystem sensitive to disturbance? First, numerous species travel there for a short, two-month growing season. The organisms interact with each other and the environment in diverse ways; therefore, a single disturbance could potentially have farreaching implications on a diverse number of species.


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Concept 55.4 Biological and geochemical processes cycle nutrients and water in ecosystems Pay particular attention to the nutrient cycles in Figure 55.14 in your text. Note the key processes in each cycle. 28. Use the following figure to describe the water cycle. Specify the roles of evaporation, transpiration, and rainfall. See page 1244 of your text for the labeled figure. The main processes driving the water cycle are evaporation of liquid water by solar energy, condensation of water vapor into clouds, and precipitation. Transpiration by terrestrial plants also moves large volumes of water into the atmosphere. Surface and groundwater flow can return water to the oceans, completing the water cycle. 29. Use this figure to describe the carbon cycle. In doing so, explain how carbon enters the living system and how it leaves, indicate the role of microorganisms in the cycle, and identify the reservoir for carbon. Give some thoughts to how concepts from the chapters on photosynthesis and cellular respiration are tied to the carbon cycle. See page 1245 of your text for the labeled figure. Photosynthesis by plants and phytoplankton removes substantial amounts of atmospheric CO2 each year. This quantity is approximately equaled by CO2 added to the atmosphere through cellular respiration by producers and consumers. The burning of fossil fuels and wood is adding significant amounts of additional CO2 to the atmosphere. Over geologic time, volcanoes are also a substantial source of CO2. Write the equation for photosynthesis here: 6 CO2 + 6 H2O  C6H12O6 + 6 O2 Write the equation for cellular respiration here: C6H12O6 + 6 O2  6 CO2 + 6 H2O + ATP Note that the raw materials for photosynthesis are the products of cellular respiration. The organic molecules used in cellular respiration are the result of photosynthesis. Matter cycles! 30. Use the following diagram to describe the nitrogen cycle. In doing so, indicate the role of microorganisms in nitrogen fixation, nitrification, and denitrification See page 1246 of your text for the labeled figure. The major pathway for nitrogen to enter an ecosystem is via nitrogen fixation, the conversion of N2 to forms that can be used to synthesize organic nitrogen compounds. Certain bacteria, as well as lightning, fix nitrogen naturally. Nitrogen inputs from human activities now outpace natural inputs on land. Two major contributors are industrially produced fertilizers and legume crops that fix nitrogen via bacteria in their root nodules. Other bacteria in soil convert nitrogen to different forms (see also Figure 37.9). Some bacteria carry out denitrification, the reduction of nitrate to nitrogen gases. Human activities also release large quantities of reactive nitrogen gases, such as nitrogen oxides, to the atmosphere.


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31. Review the Case Study: Nutrient Cycling in the Hubbard Brook Experimental Forest. What effect has deforestation been shown to have on chemical cycling? Experimental deforestation of a watershed dramatically increased the flow of water and minerals leaving the watershed. The Hubbard Brook deforestation study showed that the amount of nutrients leaving an intact forest ecosystem is controlled mainly by the plants. Large amounts of calcium, nitrates, and potassium were washed into the creeks below the deforested areas. Retaining nutrients in ecosystems helps to maintain the productivity of the systems and, in some cases, to avoid problems caused by excess nutrient runoff. Concept 55.5 Restoration ecologists help return degraded ecosystems to a more natural state 32. What is the goal of restoration ecology? Restoration ecologists seek to initiate or speed up the recovery of degraded ecosystems. 33. Restoration ecology uses two key strategies. Explain how each strategy works: bioremediation: Using organisms—usually prokaryotes, fungi, or plants—to detoxify polluted ecosystems is known as bioremediation (see Chapter 27). Some plants and lichens adapted to soils containing heavy metals can accumulate high concentrations of potentially toxic metals such as zinc, nickel, lead, and cium in their tissues. Restoration ecologists can introduce such species to sites polluted by mining and other human activities and then harvest these organisms to remove the metals from the ecosystem. biological augmentation: In contrast to bioremediation, which is a strategy for removing harmful substances from an ecosystem, biological augmentation uses organisms to add essential materials to a degraded ecosystem. To augment ecosystem processes, restoration ecologists need to determine which factors, such as chemical nutrients, have been lost from a system and are limiting its recovery. Test Your Understanding Answers Now you should be ready to test your knowledge. Place your answers here: 1. c 2. b 3. a 4. c 5. a 6. b 7. d 8. d Solution to Question 24: Grass (1,000 J)  grasshopper (100 J)  lizard (10 J)  crow (1 J)


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