What might be the adaptive significance of these unusual forests growing the way they do in this marginal habitat?
Taproot formation is impossible, so trees developed shallow root beds and easily tilt
Imagine that you are managing a large game ranch. You know from historical accounts that a species of deer used to live there, but they have been extirpated. You decide to reintroduce them. After doing some research to determine what might be an appropriately sized founding population, you do so. You then watch the population increase for several generations, and graph the number of individuals (vertical axis) against the number of generations (horizontal axis). The graph will likely appear as
a "J," increasing with each generation
Which of the following statements best describes the effect of climate on biome distribution?
Not only is the average climate important in determining biome distribution, but so is the pattern of climatic variation
The growing season would generally be shortest in which of the following biomes?
northern coniferous forest
Trees are not usually found in the tundra biome because of
permafrost
Which of the following levels of ecological organization is arranged in the correct sequence from most to least inclusive?
ecosystem, community, population, individual
Which of the following choices includes all of the others in creating global terrestrial climates?
differential heating of Earth's surface
Why is the climate drier on the leeward side of mountain ranges that are subjected to prevailing winds?
Pushed by the prevailing winds on the windward side, air is forced to rise, cool, condense, and drop its precipitation, leaving drier air to descend the leeward side.
What would be the effect on climate in the temperate latitudes if Earth were to slow its rate of rotation from a 24-hour period of rotation to a 48-hour period of rotation?
There often would be a larger range between daytime high and nighttime low temperatures
Palm trees and subtropical plants are commonplace in Land's End, England, whose latitude is the equivalent of Labrador in coastal Canada, where the local flora is subarctic. Which statement best explains why this apparent anomaly exists between North America and Europe?
Regions such as Labrador are actually colder than England because colder arctic air is pulled down to eastern North America and not to England
In mountainous areas of western North America, north-facing slopes would be expected to
support biological communities similar to those found at higher elevations on similar south-facing slopes.
Deserts typically occur in a band around 30 degrees north and south latitude because
descending air masses originating from the tropics tend to be dry
Which of the following events might you predict to occur if the tilt of Earth's axis relative to its plane of orbit was increased to 33 1/2 degrees?
Summers and winters in the United States would likely become warmer and colder, respectively
Imagine some cosmic catastrophe jolts Earth so that its axis is perpendicular to the orbital plane between Earth and the sun. The most obvious effect of this change would be
the elimination of seasonal variation
The main reason polar regions are cooler than the equator is that
sunlight strikes the poles at a lower angle
Generalized global air circulation and precipitation patterns are caused by
rising, warm, moist air masses that cool and release precipitation as they rise and then, at high altitude, cool and sink back to the surface as dry air masses after moving north or south of the tropics.
Air masses formed over the Pacific Ocean are moved by prevailing westerlies where they encounter extensive north-south mountain ranges, such as the Sierra Nevadas and the Cascades. Which statement best describes the outcome of this encounter between a landform and an air mass?
The warm, moist Pacific air rises and cools, releasing precipitation as it moves up the windward side of the range, and this cool, now dry air mass heats up as it descends on the leeward side of the range
Coral reefs can be found on the southeast coast of the United States but not at similar latitudes on the southwest coast. Differences in which of the following most likely account for this?
ocean currents
What is the limiting factor for the growth of trees in the tundra?
permafrost
In which of the following terrestrial biome pairs are both dependent upon periodic burning?
chaparral and savanna
Fire suppression by humans
can change the species composition within biological communities.
Which of the following statements best describes the interaction between fire and ecosystems?
Many kinds of plants and plant communities have adapted to frequent fires.
If a meteor impact or volcanic eruption injected a lot of dust into the atmosphere and reduced the sunlight reaching Earth's surface by 70% for one year, which of the following marine communities most likely would be least affected?
deep-sea vent
Which statement describes how climate might change if Earth was 75% land and 25% water?
Earth's daytime temperatures would be higher and nighttime temperatures lower.
Which of the following examples of an ecological effect leading to an evolutionary effect is most correct?
A few individuals with denser fur survive the coldest days of an ice age, and the reproducing survivors of the ice age all have dense fur.
Which of the following are important biotic factors that can affect the structure and organization of biological communities?
predation, competition
A certain species of pine tree survives only in scattered locations at elevations above 2,800 m in the western United States. To understand why this tree grows only in these specific places, an ecologist should
investigate the various biotic and abiotic factors that are unique to high altitude.
Studying species transplants is a way that ecologists
determine if dispersal is a key factor in limiting distribution of organisms.
A population is correctly defined as having which of the
following characteristics?
I. inhabiting the same general
area
II. belonging to the same species
III. possessing a
constant and uniform density and dispersion
I and II only
An ecologist recorded 12 white-tailed deer, Odocoileus virginianus, per square mile in one woodlot and 20 per square mile in another woodlot. What was the ecologist comparing?
density
Uniform spacing patterns in plants such as the creosote bush are most often associated with
competitive interaction between individuals of the same population.
Which of the following groups would be most likely to exhibit uniform dispersion?
red squirrels, who actively defend territories
To construct a reproductive table for a sexual species, one needs to
keep track of the females in a cohort.
Which of the following examples would most accurately measure the density of the population being studied?
counting the number of moss plants in 1-m2 quadrats
Long-term studies of Belding's ground squirrels show that immigrants move nearly 2 km from where they are born and become 1-8% of the males and 0.7-6% of the females in other populations. On an evolutionary scale, why is this significant?
These immigrants provide a source of genetic diversity for the other populations.
Which of the following sets of measurements would best describe a populations physical structure and vital statistics?
density, dispersion, and demographics
Which of the following scenarios would provide the most legitimate data on population density?
Count the number of pine trees in several randomly selected 10-m by 10-m plots and extrapolate this number to the fraction of the study area these plots represent.
Which of the following is the best natural example of uniform distribution?
territorial songbirds in a mature forest during mating season
Which of the following choices would most likely promote random distribution?
homogeneous chemical and physical factors in the environment
Which of the following best defines a cohort?
a group of the individuals from the same age group, from birth until they are all dead
Why do some invertebrates, such as lobsters, show a "stair-step" survivorship curve?
Many invertebrates molt in order to grow, and they are vulnerable to predation during their "soft shell" stage.
A population of ground squirrels has an annual per capita birth rate of 0.06 and an annual per capita death rate of 0.02. Calculate an estimate of the number of individuals added to (or lost from) a population of 1,000 individuals in one year.
40 individuals added
Exponential growth of a population is represented by dN/dt =
r max N
Starting from a single individual, what is the size of a population of bacteria that reproduce by binary fission every 20 minutes at the end of a 2-hour time period? (Assume unlimited resources and no mortality.)
64
Which of the following is the equation for zero population growth (ZPG)?
b=m or r=0
In July 2008, the United States had a population of approximately 302,000,000 people. How many Americans were there in July 2009, if the estimated 2008 growth rate was 0.88%?
304,700,000
In 2008, the population of New Zealand was approximately 4,275,000 people. If the birth rate was 14 births for every 1,000 people, approximately how many births occurred in New Zealand in 2008?
60,000
Consider two forests: one is an undisturbed old-growth forest, whereas the other has recently been logged. In which forest are species likely to experience exponential growth, and why?
Logged, because the disturbed forest affords more resources for increased specific populations to grow.
Logistic growth of a population is represented by dN/dt =
rmaxN(K−N)K.
As N approaches K for a certain population, which of the following is predicted by the logistic equation?
The growth rate will approach zero.
In models of logistic population growth,
the population growth rate slows dramatically as N approaches K.
Carrying capacity is
the maximum population size that a particular environment can support.
Which of the following causes populations to shift most quickly from an exponential to a logistic population growth?
competition for resources
Often the growth cycle of one population has an effect on the cycle
of another. As moose populations increase, for example, wolf
populations also increase. Thus, if we are considering the logistic
equation for the wolf population,
dN/dt=rN(K−N)K,
which of
the factors accounts for the effect of the moose population
K
Natural selection involves energetic trade-offs between
high survival rates of offspring and the cost of parental care.
The three basic variables that make up the life history of an organism are
age when reproduction begins, how often reproduction occurs, and how many offspring are produced per reproductive episode.
Which of the following pairs of reproductive strategies is consistent with energetic trade-off and reproductive success?
Female rabbits that suffer high predation rates may produce several litters per breeding season, and coconuts produce few fruits, but most survive when they encounter proper growing conditions.
Which of the following is characteristic of K-selected populations?
offspring with good chances of survival
Which variables define the ecological life history of a species?
the age at which reproduction begins, frequency of reproduction, and the number of offspring for each reproductive episode
In which of the following situations would you expect to find the largest number of K-selected individuals?
an old-growth forest
Which of the following is most likely to contribute to density-dependent regulation of populations?
intraspecific competition for nutrients
Why do populations grow more slowly as they approach their carrying capacity?
Density-dependent factors lead to fewer births and increased mortality.
Which of the following could be a density-independent factor limiting human population growth?
earthquakes
In the ecological development of terrestrial biomes, which factor is most dependent on all the others?
the species of colonizing animals
Which of the following environmental features might influence microclimates?
All of the options are correct
large boulder
log on the forest floor
freshly plowed field
forest canopy
Imagine that a deep temperate zone lake did not "turn over" during the spring and fall seasons. Based on the physical and biological properties of limnetic ecosystems, what would be the difference from normal seasonal turnover?
The lake would suffer a nutrient depletion in its surface layers.
Which pattern of reproduction is correctly paired with a species?
iteroparity–elephant