What changes in sea surface temperatures and atmospheric pressures over the Pacific Ocean accompany El Niño? What physical changes accompany La Niña? How do El Niño and La Niña affect precipitation in North America, South America, and Australia?
> How could you test the hypothesis that low overlap in root systems in creosote bush populations (see fig. 9.14) is the result of ongoing competition? Figure 9.14: The actual root systems were not circular and If excavated sh
> Are the concepts of “small” versus “large” scale the same for all organisms?
> Which results clearly show the influence of intrasexual selection on male scorpionfly mating success?
> What led Thornhill to conclude that mating success by male scorpionflies is tied to the quality of nuptial offerings presented by males?
> In this chapter, we discussed water relations of tenebrionid beetles from the Namib Desert. However, members of this family also occur in moist temperate environments. How should water loss rates vary among species of tenebrionids from different environm
> What evidence is there that the availability of dead insects for scorpionfly feeding is limited in nature?
> How are water and temperature regulation related in many terrestrial organisms?
> During severe droughts, some of the branches of shrubs and trees die, while others survive. How might losing some branches increase the probability that an individual plant will survive a drought?
> In general, what must be true of the chemical energy of the products of chemosynthesis compared to that of the reactants, for instance, the chemical energy of the product S0 (elemental sulfur) versus that of the reactant H 2 S shown in figureÂ&nbs
> The tiger beetle Cicindela oregona (see figs. 6.15 and 6.16) has a distribution that extends from Arizona through the temperate rain forests of Alaska. Why should the amounts of cuticular hydrocarbons vary geographically among populations of
> How might immigration oppose the effects of genetic drift on genetic diversity in a small population?
> If your research team obtained the hypothetical results described in question 1, what could you conclude about the principle of allocation?
> If growing lines of Escherichia coli at 20 8 C for 2,000 generations increased their fitness at 20 8 C without reducing their fitness at 40 8 C, how would the distribution of points in figure 5.7 change? Figure 5.7:
> How does highly selective mating by females (for example, see fig. 8.10) affect the potential for Hardy-Weinberg equilibrium? Figure 8.10:
> Why is genetic drift more probable in small populations than in large populations?
> Compare the water budgets of the tenebrionid beetle, Onymacris, and the kangaroo rat, Dipodomys, shown in figures 6.9 and 6.10. Which of these two species obtains most of its water from metabolic water? Which relies most on condensation of fo
> In the course of studies by Simberloff and Wilson (1969) and Simberloff (1976), several mangrove islands were defaunated and several were partially destroyed to reduce island area. Do such experiments raise ethical issues?
> What result would have been grounds for Diamond to reject the equilibrium model of island biogeography based on his studies of the California Channel Islands (see fig. 22.10)? Figure 22.10:
> Why are virtually all estimates of immigration and extinction rates on islands underestimates of the true rates?
> How will global warming affect the proportion of the earth’s water that resides in the oceans?
> What are two ways in which the cutting of tropical forests and replacing them with lower productivity cattle pastures affect the global carbon balance?
> In figure 22.7, the number of mammal species on the isolated mountain ranges varies greatly for a given distance from large montane areas, for instance, at a distance of 150 km. What is the likely source of much of this variation? Fig
> In chapter 21 we discussed the influences of habitat fragmentation from the perspective of populations (see figs. 21.11 and 21.12). Drawing from the information in this section, how do you think fragmentation will affect species richnessâ€
> What are the primary mechanisms producing the great differences in succession rates in forests, rocky intertidal, and stream communities?
> In the landscapes shown in figure 21.4, what is patch and what is matrix? Figure 21.4:
> Why do primary forest succession at Glacier Bay and secondary forest succession in the Southeastern United States occur at such different rates (compare figs. 20.2 and 20.4)? Figure 20.2: Figure 20.4: Continue
> Leaf water potential is typically highest just before dawn and then decreases progressively through midday. Should lower leaf water potentials at midday increase or decrease the rate of water movement from soil to a plant? Assume soil water potential is
> What are the relative fluxes of nitrogen through fixation and denitrification on land and in the oceans (see fig. 19.3)? Figure 19.3: Annual N fixation slightly exceeds denitrification. Annual N fixation by lightning is smal
> Do the oceans act as a source or a sink for phosphorus (refer to fig. 19.2)? Figure 19.2: Pmoving from land to atmosphere Human movement of P from terestrial to fresh- water ecosystems Atmospheric deposition of P onto land Au
> How would actual evapotranspiration and net primary production in the desert dune ecosystem, which is a hot desert, and the arctic and alpine tundra ecosystems likely respond to a significant increase in precipitation?
> How are the desert dune ecosystem and the arctic and alpine tundra ecosystems indicated in figure 18.2 the same? Figure 18.2: Terrestrial primary production increases with actual evapotranspiration. 3,200- Tropical forest 1,6
> Why was precipitation alone, without temperature, sufficient to account for most of the variation in grassland net primary production across central North America (see fig. 18.3)? Figure 18.3: Primary production in grassland
> In what other main way did Tscharntke simplify his study of trophic interactions in the wetland along the Elbe River?
> What was the primary way by which Tscharntke simplified the food web representing the interactions of blue tits and feeding on insects living on the wetland reed Phragmites australis (see fig. 17.5)? Figure 17.5: Identifying the stro
> What are the main advantages of including only strong linkages in a food web?
> In Inouye and Taylor’s study, why wasn’t the comparison of seed predation on plants naturally with and without ants sufficient to demonstrate the influence of ants on rates of seed predation?
> Why did the massive sampling efforts associated with the moth collections shown in figure 16.4 reveal only a portion of the lognormal distribution, while the studies of birds and plants produced the nearly complete lognormal distributions sho
> Distinguish among vapor pressure deficit, osmotic pressure, and water potential. How can all three phenomena be expressed in the same units of measure: pascals?
> Why do smaller samples result in only part of the bellshaped curve that is characteristic of the lognormal distribution?
> Why did Johnson’s control consist of a sterilized mixture of soils from the fertilized and unfertilized study areas?
> Why did Johnson create her inocula by mixing sterilized and unsterilized soils from the fertilized and unfertilized study areas?
> Large darter species produce larger numbers of smaller eggs compared to smaller darter species (see figs. 12.3 and 12.4). Consequently, would you expect to find more genetic differences along the length of a river system among small darters or large dart
> How did Moore’s laboratory and field experiments complement each other?
> Why did Moore conduct “blind” behavioral observations— that is, without knowing whether individual Armadillidium was infected or not?
> How might using other indicators of competition, such as growth rate, reproductive rate, and size at maturity, have affected Grosholz’s conclusions regarding lack of food limitation in his study populations?
> Do you think that Grosholz might have observed food limitation if he had used higher densities of Porcellio scaber in his experiments?
> Why did Jakobsson and Eriksson (2000) conduct their study of the relationship between seed size and seedling size in a greenhouse?
> Why did Westoby, Leishman, and Lord (1996) include five floras on three continents in their study?
> The body temperature of the seashore isopod Ligia oceanica is 30 8 C under stones, where the relative humidity is 100%, but 26 8 C on the surface, where it is exposed to full sun and the relative humidity is 70%. Edney (1953) proposed that the isopods in
> African annual killifish live in temporary pools, where their populations survive the dry season as eggs that lie dormant in the mud, developing and hatching only when the pools fill each wet season. In contrast, the guppy, a common aquarium fish, lives
> Why do many populations of exotic species, such as zebra mussels in the Great Lakes (see fig. 3.41b) or Eurasian collared doves in Europe, often grow at exponential rates for some time following their introductions into a new environment? Figure 3.41b:
> What was the major assumption underlying Bennett’s (1983) use of pollen deposited in lake sediments to estimate the postglacial population size of Scots pine?
> What do female guppies potentially gain by mating with colorful males?
> Ecologists who have used clear plastic sheets coated with adhesive to trap the adults of aquatic insects flying over rivers have found that the side of the sheets facing downstream generally traps more of the flying adults than the upstream-facing side.
> Why might a species, such as the Eurasian collared dove, be less threatened by rapid climate change than hemlock or maple trees?
> How might biological and physical aspects of the environment interact to influence a species’ geographic distribution?
> How may a species respond to climate change?
> In Endler’s field experiment (see fig. 8.6), why did male colorfulness increase in the absence of effective predators and not just remain unchanged? Figure 8.6: Experimental design Two hundred guppies transferred from high predati
> Why did John Endler take great care to put the same colors of gravel in the same proportions into all of his greenhouse ponds (see fig. 8.5)? Figure 8.5: Experimental conditions No predation Guppies only High predation Low predation Rivulus Pike ci
> In most of the examples discussed in chapter 5, we saw a close match between the characteristics of organisms and their environment. However, natural selection does not always produce an optimal, or even a good, fit of organisms to their environments. To
> Why does the ongoing increase in atmospheric CO 2 (see chapter 23, fig. 23.21) not give guaranteed advantage to C 3 plants over C 4 plants? Figure 23.21: 350 Atmospheric CO, began to increase exponentially in the middle 1800s. 300 250 • Mauna Loa O
> How are C 4 and CAM photosynthesis similar? How are they different?
> What environmental conditions favor plants with C 3 photosynthesis? Why?
> Why are water potentials in nature generally negative?
> Which has a higher free energy content, pure water or seawater?
> Why are the two curves shown in figure 6.2 so similar? Figure 6.2: Water vapor in air can be measured either as grams of vapor per cubic meter of air... ...or by the pressure exerted by the water vapor in air. 40 30 20 10 10
> Contrast the microclimates of the aboveground parts of desert plants to that of their roots.
> Why is evaporative cooling by various animal species so effective?
> What advantages might the warm microenvironments of Dryas flowers offer to the insects attracted to them?
> What is a fundamental evolutionary implication of the large amounts of genetic variation commonly documented in natural populations?
> Some plants and grasshoppers in hot environments have reflective body surfaces, which make their radiative heat gain, H r, less than it would be otherwise. If you were to design a tiger beetle that could best cope with thermal conditions on black beaches
> What would you expect to see in figure 4.4 if alpine, mid-elevation, and lowland populations of P. glandulosa were not different genetically?
> Can we be confident that differences in growth within P. glandulosa clones grown at different elevations were not the result of genetic differences? Why?
> The example of El Niño and the Great Salt Lake might lead us to what general conclusion concerning the concepts of top-down and bottom-up control?
> How does the example of El Niño and the Great Salt Lake confound the concepts of top-down and bottom-up control?
> How are the influences of El Niño and La Niña related to the concepts of top-down versus bottom-up control of populations, communities, and ecosystems?
> Why would the soils in tropical rain forests generally be depleted of their nutrients more rapidly compared to the nutrients in temperate forest soils?
> Why do those regions, whether tropical, desert, or temperate, that include high mountains tend to be the most biologically diverse?
> The patterns shown in figure 21.28 support Minnich’s hypothesis that fire protection in southern California would produce a difference in median burn area. However, do these results show conclusively that the differences in burn area in
> Why is there no one factor that seems to explain latitudinal gradients in species diversity?
> Can a dominant species of tree in a forest or coral on a coral reef (see fig. 17.17, p. 386) be an ecosystem engineer? Figure 17.17: Species with low biomass Dominant species are Keystone species are those whose influence but large effects on commun
> The section on avoiding temperature extremes focused mainly on animals. What are some of the ways in which plants avoid temperature extremes? Bring cold and hot environments into your discussion. Some of the natural history included in chapter 2 might be
> How are “landscape engineers” similar to keystone species? How are they different?
> What pattern of colonization by Gigartina in Sousa’s Ulva removal experiment would have been consistent with the facilitation model?
> Suppose Gigartina had colonized the plots where Sousa had removed Ulva and where he had left Ulva in place at the same rates (see fig. 20.21). This result would be consistent with which successional model? Figure 20.21: Rem
> What is the role of disturbance in the Connell and Slatyer succession model (see fig. 20.20)? Figure 20.20: Space available for colonization. Succession begins. Only early successional species can establish. Any species able
> Why might restoration of native plant communities to their original structure be difficult after exotic plants such as Myrica, in Hawaii, have occupied a site for a significant length of time?
> How might nitrogen and phosphorus composition and excretion ratios differ for invertebrate consumers compared to vertebrate consumers?
> The Great Plains of North America once supported bison herds numbering in the tens of millions. How did the near extermination of the bison likely affect nutrient cycling on the Great Plains?
> If plant species richness and functional group composition accounted for one third to two thirds of variation in primary production across study plots, what other f actors likely accounted for the remainder of differences in primary production among plot
> What does the effect of legumes on primary production in the Tilman experiment suggest about other factors limiting production on the experimental plots?
> Can a trait with no heritability, h2= 0, evolve? Explain your answer.
> When we reviewed how some organisms use torpor, hibernation, and estivation to avoid extreme temperatures, we discussed the idea of energy savings. However, organisms do not always behave in a way that saves energy. For instance, when food is abundant hu
> Is the index of resilience used by Valett and his colleagues consistent with the biomass accumulation model of Bormann and Likens?
> How does the combined evidence from studies of the flora of Mediterranean regions (fig. 22.22) and the diversity of trees in temperate forest regions increase confidence that historical differences can outweigh the potential influ
> Why should history have such a strong influence on regional diversity patterns?
> How might taxonomic resolution—that is, how precisely we identify organisms—influence an assessment of community stability?
> What causes community resilience?
> Flood control on streams and rivers has often been cited as a potential threat to populations of aquatic animals and riparian trees that require flooding for reproduction. How might flow regulation also alter stream ecosystem nutrient dynamics?
> What do the results of Likens and Bormann and that of Turner and her colleagues suggest about the role of vegetation in preventing losses of nitrogen in forest ecosystems?
