Question: What do the studies of Margaret Davis

> In their initial studies, leading to the trophic cascade hypothesis, Stephen Carpenter and his colleagues (1991) found a negative correlation between zooplankton size and phytoplankton primary production. What does this mean (see Investigating the Eviden

> According to the intermediate disturbance hypothesis, could human disturbance sustain higher levels of species diversity than in the absence of human disturbance?

> In many regions, native pollinator insects seem to be declining. Why is this a cause for concern among conservationists and ecologists?

> Bshary studied changes in fish species richness in response to both natural and experimental removals and additions of the cleaner fish Labroides dimidiatus (see fig. 17.18). Why did he not just focus on the response of fish species richness

> If disturbance can foster higher species diversity, why is human disturbance often (though not always) associated with reduced species diversity?

> Could protecting forests that once burned with regular frequency, due to lightning strikes, lead to reduced plant diversity within a mountain forest landscape of 25 km2  (~10 mi2)?

> Why did Brown and colleagues repeat their large granivore experiment (see fig. 13.24)? Figure 13.24: Before removal After removal 30- Dipodomys spp. 25 - • Control plots Removal plots 20 - 15 - Dipodomys numbers were immediat

> Why should there be strong selection on periodical cicadas for highly synchronous emergence?

> What factors make coexistence of predators and prey less likely in a laboratory setting than in nature?

> What does the increase in small granivore populations but lack of response by populations of insectivorous rodents suggest about the nature of competition between rodents in Brown’s Arizona study area (see fig. 13.23)? Fig

> The Applications section reviews how the studies of Bruno Baur and Anette Baur (1993) have documented the local extinction of the land snail Arianta arbustorum. Their research also shows that these extinctions may be due to reduced egg hatching at higher

> What do you think would have happened to the Galium sylvestre on acidic soil if Tansley had continued his experiment for a few more years?

> What are the evolutionary implications of the fact that larger coalitions of male lions consist almost entirely of close relatives (see fig. 8.25)? Figure 8.25: 75 Males in coalitions of two or three are often unrelated,.. 5

> The last major natural reproduction by Rio Grande cottonwoods, which produced the large number of 40- and 50-year-old trees documented by Howe and Knopf (1991), occurred before the last major dam was built on the river. Is there any evidence for reproduc

> Can a healthy population that is not in danger of extinction have an age structure that shows years of reproductive failure?

> Both R0 and r indicate that the mud turtle population in Ellenton Bay is in decline. Is there any way that this population could be maintained for many generations even with such negative indicators?

> Suppose that you are managing a population of an endangered species that has been reduced in numbers throughout its historic range and that your goal is to increase the size of the population. What values of R0 would meet your management goals?

> Of the three populations pictured in figures 10.19, 10.20, and 10.21, which is most likely to have a stable age distribution? Figures 10.19: Figures 10.20: Continue to next pages……. Figures 10.21:

> What evidence does colony structure offer in support of the idea that both leaf-cutter ants and naked mole rats must vigorously defend their colonies from predators and invaders?

> What are two major ecological challenges favoring colony living that are shared by leaf-cutter ants and naked mole rats?

> How would a queen ant, or other eusocial hymenopteran queen, mating with several males affect the relatedness of workers within a colony? If common in social hymenoptera, how would queens mating with several males affect the potential of kin selection to

> Figure 5.8 shows how temperature influences the activity of acetyl cholinesterase in rainbow trout. Assuming that the other enzymes of rainbow trout show similar responses to temperature, how would trout swimming speed change as environmental temperature

> Why did Tilman and Cowan plant several pots of each species in each of their growing conditions?

> Do patterns of feeding by bluegills (see fig. 7.25) include any evidence that these consumers ignore certain potential prey? Figure 7.25: 70 40 The most abundant prey in the environment are approximately I mm long. 20 0- 40-

> According to optimal foraging theory, under what conditions should a predator add a new prey species to its diet?

> Why do the managers of captive breeding and reintroduction programs for endangered species try to maintain high levels of genetic diversity?

> Why might the frequency of torpor and hibernation be more common among animals in tropical dry forest compared to those living in tropical rain forests?

> Why don’t hummingbirds save energy by going into torpor at night even when food supplies are abundant? In other words, what would be a possible disadvantage of routine, nightly torpor?

> What is the ecological significance of Frankham’s finding lower genetic variation in smaller, isolated island populations?

> Would secondary production in a stream ecosystem dependent on inputs of detritus from a surround forest change, if detrital inputs to the stream, for example leaves falling from nearby trees, were reduced? How so?

> Is it possible for two consumer populations to have equal biomass but differ in secondary production?

> How can energy losses between trophic levels limit the number of trophic levels in an ecosystem?

> J. L. Mosser and colleagues (1974) found that populations of the bacterium Sulfolobus living at different temperatures had different optimal temperatures for sulfur oxidation. Use natural selection to explain these patterns. Design an experiment to test

> How might energy and nutrient relations explain the lower population densities of birds compared to comparable-sized mammals (see fig. 9.20)? Figure 9.20: Overall, average population density Many aquatic invertebrates live a

> What are some advantages of Damuth’s strict focus on herbivorous mammals in his analysis of the relationship between body size and population density (see fig. 9.19)? Figure 9.19: Average population density

> According to Hamilton’s rule, would helpers derive greater benefit through kin selection by contributing the same amount of help toward raising a full sibling or a half sibling?

> The Ligons found that most of the young woodhoopoes tended by helpers were either full siblings or half siblings of the helpers. If full siblings were genetically related to the helpers by an average of 50%, what was the genetic relationship between help

> While an ecologist may focus on a particular level of ecological organization shown in figure 1.1, might other levels of organization be relevant, for example, does an ecologist studying factors limiting numbers in a population of zebras need to consider

> How does the level of ecological organization an ecologist studies influence the questions he or she poses?

> How were the warbler studies of Robert MacArthur and those that focused on the American redstart similar? How did they differ?

> What aspects of Nalini Nadkarni’s research identify it as “ecosystem ecology”? Give examples of research in forest canopies that would address other levels of ecological organization (for examples, se

> The discussion of the research by Margaret Davis and her colleagues did not identify the questions that they addressed. What research questions can we infer from the above description of their work?

> How could you change the Lotka-Volterra model of competition we discussed in chapter 13 into a model of mutualism? Would the resulting model be a cost-benefit model or a population dynamic model?

> Imagine a desert beetle that uses behavior to regulate its body temperature above 35 8 C. How might this beetle’s use of microclimates created by shrubs, burrows, and bare ground change with the season?

> To date, which biomes have been the most heavily affected by humans? Which seem to be the most lightly affected? How would you assess human impact? How might these patterns change during this century?

> Biologists have observed much more similarity in species composition among boreal forests and among areas of tundra in Eurasia and North America than among tropical rain forests or among Mediterranean woodlands around the globe. Can you offer an explanat

> English and other European languages have terms for four seasons: spring, summer, autumn, and winter. This vocabulary summarizes much of the annual climatic variation at midlatitudes in temperate regions. Are these four seasons useful for summarizing ann

> How is the physical environment on mountains at midlatitudes similar to that in tropical alpine zones? How do these environments differ?

> During the course of the studies reviewed in this chapter, each scientist or team of scientists measured certain variables. What major variable studied by Margaret Davis and her research team distinguishes their work from that of the other research revie

> Although Nalini Nadkarni’s studies of the rain forest canopy addressed a question related to ecosystem structure, the patterns of nutrient storage in rain forest canopy resulted from the biology of individual organisms, populations of organisms, and comm

> What could you do to verify that the distinct feeding zones used by the warblers studied by MacArthur (see fig.  1.3) are the result of ongoing competition between the different species of warblers? How might you examine the role of competiti

> What are the pitfalls of subdividing nature in the way it is represented in figure 1.1? In what ways does figure 1.1 misrepresent nature? Figure 1.1: Biosphere What role does concentration of atmospheric CO, play in the regul

> Faced with the complexity of nature, ecologists have divided the field of ecology into sub disciplines, each of which focuses on one of the levels of organization pictured in figure 1.1. What is the advantage of developing such sub discipline

> Many species of plants and animals that are associated with boreal forests also occur on mountains far to the south of the boreal forests. Using what you have learned about microclimates, predict how aspect and elevation would influence their distributio

> Geologists, atmospheric scientists, and oceanographers have been conducting global-scale studies for some time. What role will information from these disciplines play in the study of global ecology? Why will global ecological studies generally be pursued

> You probably suggested altitude in response to question 5 because of its important influence on climate. Some of the earliest studies of the geographic distribution of vegetation suggested a direct correspondence between latitudinal and altitudinal varia

> We focused much of our discussion of biomes on their latitudinal distribution. The reasonably predictable relationship among latitude and temperature and precipitation provides a link between latitude and biomes. What other geographic variable might affe

> Use what you know about atmospheric circulation and seasonal changes in the sun’s orientation to earth to explain the highly seasonal rainfall in the tropical dry forest and tropical savanna biomes. (Hint: Why does the rainy season in these biomes come

> Describe global patterns of atmospheric heating and circulation. What mechanisms produce high precipitation in the tropics? What mechanisms produce high precipitation at temperate latitudes? What mechanisms produce low precipitation in the tropics?

> Draw a typical soil profile, indicating the principal layers, or horizons. Describe the characteristics of each layer.

> Daniel Janzen (1981a, 1981b) proposed that the seeds of the Guanacaste tree were once dispersed by several species of large mammals that became extinct following the end of the Pleistocene about 10,000 years ago. There may have been other plant species w

> Biological interactions may also affect lake systems. How does the recent history of the Great Lakes suggest that the kinds of species that inhabit a lake influence the nature of the lake environment and the composition of the biological community?

> How could you test the generalization that lake primary production and the composition of the biota living in lakes are strongly influenced by the availability of nutrients such as nitrogen and phosphorus? Assume that you have unlimited resources and tha

> According to the river continuum model, the organisms inhabiting headwater streams in temperate forest regions depend mainly upon organic material coming into the stream from the surrounding forests. According to the model, photosynthesis within the stre

> How might oxygen concentration of interstitial water be related to the grain size of the sand or mud sediment? How might the oxygen concentrations of tide pools in sheltered bays compare to those on the shores of exposed headlands?

> How do classical approaches to genetic studies, such as common garden experiments, and modern molecular techniques, such as DNA sequencing, complement each other? What are the advantages and disadvantages of each?

> How might a history of exposure to wide environmental fluctuation affect the physiological tolerances of intertidal species compared to close relatives in sub tidal and oceanic environments? How might salinity tolerance vary among organisms living at dif

> Most examples of regional and latitudinal variation in species richness cited in this chapter have been terrestrial. Consider regional variation in marine biotas. Like birds on land, fish are one of the best-studied groups of marine organisms. Moyle and

> Ricklefs (1987) pointed out that many large-scale contrasts in species richness and composition cannot be explained by local processes such as competition and predation. Ricklefs proposed that differences in history and geography can leave a unique stamp

> Explain how speciation and extinction rates might be affected by the area of continents. What evidence is there to support your explanation? What does the influence of area on rates of extinction and speciation have to do with higher species richness in

> Review the major hypotheses proposed to explain the higher species richness of tropical regions compared to temperate and high-latitude regions. How are each of these hypotheses related to relative rates of speciation and extinction in tropical regions a

> Now, suppose you are going to study the bird communities on the islands shown below, which lie equal distances from the mainland but differ in area. According to the equilibrium model of island biogeography, what should be the relative rates of immigrati

> Suppose you are about to study the bird communities on the islands shown above, which are identical in area but lie at different distances from the mainland. According to the equilibrium model of island biogeography, which of the islands should experienc

> Diamond’s estimates (1969) of numbers of species immigrating and numbers that became extinct (six versus five) were virtually identical. Is this near equality in numbers of extinction and immigration consistent with the equilibrium mode

> We discussed how Diamond (1969) documented immigrations and extinctions on the California Channel Islands by comparing his censuses of the birds of the islands with the birds recorded over 50 years earlier. Disregarding the numbers for San Miguel and San

> Refer to figure 22.5, which MacArthur and Wilson (1963) used to show how isolation affects species richness on islands. Find a detailed map of the Pacific Ocean and locate New Guinea. Next locate as many of the “near,â

> How did the studies of Scott Carroll and his colleagues demonstrate rapid evolutionary adaptation to introduced soapberry plants? What advantages do a group of organisms, such as soapberry bugs, offer to researchers studying natural selection compared to

> The following data (corrected from Preston 1962a) give the area and number of bird species on islands in the West Indies: The numbers are expressed in two ways: as simple measurements and counts and as the logarithms of area and numbers of species. Use

> Succession seems to lead to predictable changes in community and ecosystem structure. Predict the characteristics of a frequently disturbed community/ecosystem versus a largely undisturbed community/ecosystem. What do your predictions suggest about a fut

> How do the activities of animals affect landscape heterogeneity? You might use either beaver or human activity as your model. What parallels can you think of between the influence of animal activity on landscape heterogeneity and the intermediate disturb

> Analyses such as Milne’s comparison (1993) of bald eagles and barnacles demonstrate that organisms of different sizes interact with the environment at very different spatial scales. With this in mind consider the experiments of Diffendo

> Use fractal geometry and the niche concept (see chapters 9, 13, and 16) to explain why the canopy of a forest should accommodate more species of predaceous insects than insectivorous birds. Assume that the numbers of bird and predaceous insect species ar

> How do the positions of patches in a landscape affect the movement of individuals among habitat patches and among portions of a metapopulation? Again, consider the hypothetical landscapes shown in question 5. Which of the two landscapes would promote the

> Consider the options for preserving patches of riverside forest shown in landscapes 3 and 4. Again, the two landscapes contain the same total area of forest but the patches in the two landscapes differ in shape. Which of the two would be most dominated b

> How do the positions of patches in a landscape affect the movement of individuals among habitat patches and among portions of a metapopulation? Again, consider the hypothetical landscapes shown in question 5. Which of the two landscapes would promote the

> The green areas represent forest fragments surrounded by agriculture. Landscapes 1 and 2 contain the same total forest area. Which landscape, 1 or 2, will contain more forest interior species? Explain. Landscape 1 Landscape 2

> How should the area of forest patches in an agricultural landscape affect the proportion of bird species in a community that are associated with forest edge habitats? How should patch area affect the presence of birds associated with forest interiors?

> How might the distribution of beak sizes in the population differ from that shown in figure 4.13, if mate choice in the population was random with respect to beak size? Figure 4.13: Higher rate of survival by birds with smal

> How does landscape ecology differ from ecosystem and community ecology? What questions might an ecosystem ecologist ask about a forest? What questions might a community ecologist ask about the same forest? Now, what kinds of questions would a landscape e

> Species have come and gone in response to changing global climates during the history of the earth. Some of the mass extinctions of the past have resulted in the deaths of over 90% of existing species. What do these biological changes suggest about the l

> Ecological succession has been compared to the development of an organism and the climax community to a kind of superorganism. F. E. Clements (1916, 1936) was the best-known proponent of this idea, and H. A. Gleason (1926, 1939), the best-known early opp

> When Mount St. Helens in Washington erupted in 1980, it created a gradient in disturbance. In the pumice plains near the eruption, the devastation was almost total. The extent of disturbance was much less in the farthest reaches of the blast zone. How mi

> In the studies of mechanisms underlying succession, ecologists have found a great deal of evidence for both facilitation and inhibition. However, they have found little evidence for the tolerance model. Explain this lack of support for the tolerance mode

> The rapid succession shown by the Sycamore Creek ecosystem is impressive. How might natural selection influence the life cycles of the organisms living in Sycamore Creek? Imagine a creek that floods about twice per century. How quickly would you expect t

> In most studies of forest succession such as that of Reiners and colleagues (1971) and Oosting (1942), researchers study succession by comparing sites of various ages. This approach is called a “space for time substitution.” What are some major assumptio

> The successional studies in Sycamore Creek produced patterns of variation in diversity that differed significantly from those observed during primary succession at Glacier Bay (see fig.  20.2), old field succession on the Piedmont

> Would you expect the number of species to remain indefinitely at the level shown in figure 20.7? Space on large, stable boulders in Sousa’s study site is dominated by the algal G. canaliculata and support 2.3 to 3.5 species,

> As we saw in figure  20.5, Johnston and Odum (1956) documented substantial change in the richness of bird species in a successional sequence going from the earliest stages in which the plant community was dominated by grasses and forbs to mat

> Suppose you are a director of a captive breeding program for a rare species of animal, such as Siberian tigers, which are found in many zoos around the world but are increasingly rare in the wild. Design a breeding program that will reduce the possibilit

> If rates of decomposition are higher in ecosystems with higher nutrient availability, how should nutrient enrichment affect rates of decomposition? Because of its effects on fungal diversity, could nutrient enrichment of ecosystems affect rates of decomp