Ecology Final (3&F)

Which of the following was a finding of Tansley's experiments with bedstraw plants?

The species that was restricted to acidic soils excluded the species that was adapted to calcareous soils when grown on acidic soils.

Suppose that rabbits are the only prey and food supply of foxes, and that the predator‒prey interaction follows Lotka‒Volterra dynamics. The mortality rate of foxes in the absence of rabbits is 0.1 per week, and the intrinsic growth rate of rabbits in the absence of predation is 0.2 per week. The capture efficiency is 0.002, and the efficiency at which rabbit biomass is converted into fox biomass is 0.2. If there are 30 foxes in a population, and 400 rabbits are present, the rate at which prey will be killed is _______ per week.

a. 24

Individuals of a plant species are counted in five transects that are each 2 x 2 meters. In these transects, 8, 15, 19, 27, and 31 plants are found. What is the density per square meter of this species?

a. 5

Which statement is true?

a. All pathogens are parasites.

The fungal parasite Cryphonectria parasitica is responsible for driving its host, the _______, to near extinction in North America.

a. American chestnut

Which of the following best explains why the mammal families in the Philippines are more similar to those in Africa than to those in New Guinea?

a. Continental drift

Which statement about environmental stochasticity is true?

a. Environmental stochasticity places grizzly bears in Yellowstone National Park at risk for extinction despite the average positive growth rate of this population.

The principle of competitive exclusion was first formulated by

a. G. F. Gause.

Which statement about parasite natural history is false?

a. It is rare for a host species to have a parasite that feeds upon only that species.

Which statement about the Black Sea is false?

a. Its waters are well oxygenated from the surface to the floor of the sea.

Which organism is an example of a hemiparasite?

a. Mistletoe

Which of the following is a resource?

a. Oxygen being depleted by zooplankton in the ocean

Which statement about the snail-trematode system studied by Dybdahl and Lively is false?

a. Parasites infected snails from their home lake less effectively than those from other lakes.

Which statement about tuberculosis (TB) is false?

a. Recent advances in medicine and vaccines have cut the worldwide death rate from TB to less than 10,000 per year.

In the simple host-pathogen model, which term describes the rate at which a susceptible individual encounters an infected individual?

a. SI

Which statement about logistic growth is false?

a. The carrying capacity is the maximum population size that can be supported by the environment for one year.

Which statement about hantavirus pulmonary syndrome (HPS), which emerged in the Four Corners region of the southwestern United States, is false?

a. The virus responsible for HPS had only been in the area for about two years prior to the outbreak.

What do the fungus that causes athlete's foot, the tick that spreads Lyme disease, and body lice all have in common?

a. They are all ectoparasites.

At low population densities, the flocking behavior of some species of birds is disrupted to the extent that the population growth rate is lower at very low densities than it is at somewhat higher densities. This is an example of

a. an Allee effect.

Moths resting on the trunks of trees often resemble the tree bark so that potential predators do not perceive them as prey. This is an example of

a. crypsis.

The most likely change caused by Vibrio cholerae in its hosts, which aides its dispersal to new hosts, is

a. diarrhea.

In Brown and Davidson's study of seed-eating rodents and ants in Arizona, the number of rodents _______ when ants were removed, and the number of ant colonies _______ when rodents were removed.

a. increased; increased

Thomas Park's studies of flour beetles and their protozoan parasite best exemplified the principle that

a. parasites can alter the outcomes of competitive interactions between species.

In humans, red blood cells that have been infected with the parasite that causes malaria (Plasmodium) are destroyed mainly in the

a. spleen.

The transmission coefficient of the hypothetical disease Dirks fever is 0.8. If the combined death and recovery rate is 0.4, what is the threshold density for Dirks fever?

b. 0.5

The size of a population of beavers in a 5 x 5-kilometer area is 675. What is the population density (in individuals per square km)?

b. 27

In a mark-recapture study to estimate the size of a rodent population, researchers catch and mark 180 individuals. Two days later, they again capture a number of rodents and find that 40% of the individuals are marked. Assuming that there have been no births, deaths, or migrations, the estimated size of the population is

b. 450

Which of the following is most likely to prevent or stop an arms race between host and parasite?

b. A trade-off between a host's survival when parasitized and its reproductive success in the absence of parasitism

Which statement about endoparasites is true?

b. All parasites living in the alimentary canal are endoparasites.

Which of the following could be considered the opposite of the density dependence seen in the standard logistic equation?

b. An Allee effect

How did Brewer manipulate the level of competition in his experiment on pitcher plants?

b. By weeding and clipping noncarnivorous competitor species

Which population dispersion pattern is most commonly seen in the field for most species?

b. Clumped

Which of the following is most likely to lead to population cycles?

b. Delayed density dependence

Which of the following is an advantage that endoparasites have over ectoparasites?

b. Ease of feeding

Two species of birds feed on berries. The birds are active at different times of the day and do not come into contact with one another. Nonetheless, the presence of one species limits the survival and reproduction of the other. What type of competition is this?

b. Exploitation

Which of the following should reduce the critical threshold for the spread of disease?

b. Increasing the rate at which individuals die

How does the protein transferrin assist in defenses against parasites?

b. It removes iron from the blood serum in vertebrate hosts and stores it in intracellular compartments.

Which statement about enslaver parasites is false?

b. Only invertebrates have been enslaved by parasites.

Ecologists have been monitoring three metapopulations of butterflies. Population A has a patch colonization rate of 0.06 and a patch extinction rate of 0.12. Population B has a patch colonization rate of 0.04 and a patch extinction rate of 0.02. Population C has a patch colonization rate of 0.10 and a patch extinction rate of 0.14. According to Levins's metapopulation model, which population(s) would be expected to persist for a long time?

b. Population B only

Which of the following helped the Black Sea recover during the 1990s?

b. Reduction in eutrophication

Which statement about malaria and the life cycle of Plasmodium is false?

b. The gamete-producing cells arise from sporozoites.

Which statement about Tilman and colleagues' studies of the diatoms Synedra and Asterionella is true?

b. The species that reduced silica levels the furthest when grown alone drove the other species to extinction.

Suppose that, instead of the results actually obtained in Brown and Davidson's experiments, the number of rodents in the ant-excluded treatment was roughly the same as the number of rodents in the control group, and the number of ants in the rodent-excluded treatment was roughly the same as the number of ants in the control group. Which of the following would you then conclude?

b. The two species have reduced competition through resource partitioning.

Insects feeding on the leaves of a plant stimulate the plant to produce more leaves. This is an example of

b. compensation.

Which equation best describes the pattern of population dynamics of the sheep in Tasmania from their introduction to the present day?

b. dN/dt = rN(1 ‒ N/K)

Population regulation occurs when

b. density-dependent factors affect birth, death, and emigration rates.

The total area of productive ecosystems required to support a particular individual or population is known as its

b. ecological footprint

The critical feature determining whether a substance is a resource is whether it

b. is required by an organism and can be used to the point of depletion.

Character displacement is likely to _______ the competition coefficients in two competing species and to _______ resource partitioning.

b. lower; increase

Nasonia vitripennis is a wasp roughly the size of a Drosophila fly. Adult females drill holes and lay eggs in the pupae of blowflies and related species. These eggs then hatch into larvae, which then eat the pupae. Thus, Nasonia vitripennis is a

b. parasitoid.

Suppose populations of a beetle species follow the logistic equation for growth. If a population is at 3/4 of its carrying capacity, and its (per capita) growth rate in the absence of density-dependent regulation is r, what is its growth rate now?

b. r/4

If soil salinity affects the growth rate of plants but is not depleted by the plants, salinity is not a(n)

b. resource.

In the simple host-pathogen model, which term describes the rate at which a disease is spread successfully?

c. (Beta)SI

If the population density of ocotillo in a desert is 15 per square kilometer, how many plants would be expected in an area that is 5 km 3 km?

c. 225

An entomology research team interested in controlling the spread of winter moths, an insect pest in the northeastern United States, samples a 150-square-meter patch of woodland with four quadrats of 1 meter by 1 meter each. In quadrats A, B, C, and D, respectively, 10, 20, 35, and 15 individual winter moths are found. What is the best estimate for the total number of winter moths in that patch of woodland?

c. 3,000

A population of turtles contained 342 individuals at the end of the year 2010. Since then, 44 have died, 37 were born, 17 immigrated, and 6 emigrated. What is the population size now?

c. 346

Assuming that their average population growth rates and all other factors are equal, which population would most likely be at risk for extinction?

c. A small population with high variation in its growth rate

Which statement about parasitic fungi, such as mildews, rusts, and smuts, is false?

c. At least some of these are hemiparasitic.

Which type of mammals would you most likely find on a small oceanic island that is 2,000 kilometers away from any other land mass and has not been colonized by humans?

c. Bats

In which way can a parasite change an ecological community?

c. By changing the outcome of species interactions

Which statement about carnivorous plants is false?

c. Carnivorous plants typically have very extensive root systems.

Suppose that two species of rabbits inhabit an area. Which technique would provide estimates of their relative population densities, as opposed to estimates of their absolute densities?

c. Comparisons of the number of tracks made by each species

Which of the following would not be an example of density-dependent factors regulating population size?

c. Predation on mosquitofish is high, regardless of population size.

Which term refers to a clone that is a physiologically independent plant?

c. Ramet

Which statement describes a finding of Wilson and Tilman's studies of the grass Schizachyrium scoparium?

c. The plants compete for both aboveground and belowground resources, and competition is most intense for whichever resources are more scarce.

Which statement does not represent an assumption of the Levins's model of metapopulation dynamics?

c. The spatial arrangement of patches determines the rate at which patches will receive colonists.

5. Which parasite would most likely be found in the human small intestine?

c. The tapeworm Taenia saginata

What is the advantage for a male cricket parasitized by hairworms to seek out water?

c. There is no advantage for the cricket; the cricket's behavior is advantageous only to the parasite.

Black walnut trees release chemicals that can be toxic to other plants. This phenomenon may be an example of _______, although experimental confirmation is still needed.

c. allelopathy

In the context of host-parasite dynamics, a latent period is the time

c. between infection in a host and its own capacity to transmit the disease.

Suppose that rabbits are the only prey and food supply of foxes, and that the predator‒prey interaction follows Lotka‒Volterra dynamics. The mortality rate of foxes in the absence of rabbits is 0.1 per week, and the intrinsic growth rate of rabbits in the absence of predation is 0.2 per week. The capture efficiency is 0.002, and the efficiency at which rabbit biomass is converted into fox biomass is 0.2. If there are initially 30 foxes and 400 rabbits, the net growth rate in the fox population will be a _______ of _______ per week.

c. gain; 1.8

Suppose that rabbits are the only prey and food supply of foxes, and that the predator‒prey interaction follows Lotka‒Volterra dynamics. The mortality rate of foxes in the absence of rabbits is 0.1 per week, and the intrinsic growth rate of rabbits in the absence of predation is 0.2 per week. The capture efficiency is 0.002, and the efficiency at which rabbit biomass is converted into fox biomass is 0.2. If there are initially 30 foxes and 400 rabbits, the overall rate of change in the rabbit population will be a _______ of _______ per week.

c. gain; 56

The studies by Dybdahl and Lively on snails and their parasites demonstrated that

c. parasites infect common genotypes of snails more easily than they infect rare genotypes.

Tapeworms have a _______, which they use to attach themselves to the insides of the host's intestine.

c. scolex

Mosquitoes infected with Plasmodium carry cells of the _______ stage of the parasite. When an infected mosquito bites a human, these cells enter the _______, where they divide into _______ that then infect red blood cells.

c. sporozoite; liver; merozoites

According to the basic host-pathogen model, if the combined death and recovery rate from a disease doubles, and the effectiveness of the disease to spread from infected to uninfected individuals also doubles, the threshold density should

c. stay the same.

A bacterium that lives inside an aphid is always classified as a(n)

c. symbiont.

A continuously growing population of alligators has a population size of 1,000 and an intrinsic rate of increase of r = 0.05 per year. Assuming that this rate of increase remains the same, about how long should it take for the population to grow larger than 4,000 individuals? (Note: The natural logarithm of 2 is about 0.70.)

d. A little more than 27 years

Which statement about the effects of the comb jelly, Mnemiopsis leidyi, on the Black Sea is true?

d. All of the above a. At the peak of its outbreak in 1989, the biomass of this comb jelly was far greater than the world's entire annual commercial fish catch. b. This comb jelly is a voracious predator of young fish and fish eggs. c. By reducing the population sizes of zooplankton, this comb jelly indirectly caused phytoplankton population sizes to increase.

Which organisms cannot defend themselves against parasites?

d. All of the above have ways of defending themselves against parasites.

Which of the following could not be a hemiparasite?

d. Any heterotroph

A bacterium that causes rash on the skin of mammals upon infection would be classified as a(n)

d. Both a and c b. endoparasite. c. microparasite.

Two similar rodent species are consistently more different from each other when they occupy the same habitat than when they live separately. What is the most likely explanation for the increased divergence when they live together?

d. Both b and c b. Character displacement c. Evolution by natural selection

Which of the following is a plausible consequence of delayed density dependence in a population that would otherwise have logistic growth?

d. Both b and c b. Dampened oscillations c. Population cycles

Which statement about studies on the importance of competition in nature is true?

d. Both b and c b. Many studies find the occurrence of competition; competition is common in nature. c. Analyses of the studies identified several possible sources of bias, including the failure of researchers to publish studies that show no significant results.

Which of the following best describes the most frequent dispersion pattern of the shrub Clematis fremontii in glades?

d. Clumped

What is the technical term for the single genetic individual?

d. Genet

Some Aleutian Islands are surrounded by urchin barrens while others are surrounded by kelp forests. Which statement gives the primary explanation for these differences?

d. Grazing by urchins prevents the formation of kelp forests.

A researcher who is interested in the number of individuals in a population of butterflies and their movement patterns would most likely use which method?

d. Mark-recapture

Which statement about populations is false?

d. Most organisms have similar capacities for dispersal.

Based on the results of Dobson and Meagher's study of bison, which statement is false?

d. The use of a vaccine successfully raised the threshold density.

Two species of grasshoppers live in the same area. They both feed on plants, but the presence of one species does not affect either the survival or the reproduction of the other. What type of competition is this?

d. This is not an example of competition.

Which statement about competition is false?

d. Two gulls fighting over a piece of fish is a form of exploitation competition.

According to the basic host-pathogen model, if the combined death and recovery rate from a disease doubles, and the effectiveness of the disease to spread from infected to uninfected individuals remains the same, the threshold density should

d. double.

In the years since Myxoma was introduced to Australia, the virus has _______ and rabbits have _______ resistance to the virus.

d. evolved to become less lethal; evolved

Suppose that a vertebrate has a mutation in the transferrin gene that makes the protein function less efficiently. Most likely, compared to individuals without the mutation, this individual would have _______ iron in its blood serum and _______ iron in the intercellular components of cells.

d. more; less

Which of the following cannot be a resource?

d. pH

Suppose that rabbits are the only prey and food supply of foxes, and that the predator‒prey interaction follows Lotka‒Volterra dynamics. The mortality rate of foxes in the absence of rabbits is 0.1 per week, and the intrinsic growth rate of rabbits in the absence of predation is 0.2 per week. The capture efficiency is 0.002, and the efficiency at which rabbit biomass is converted into fox biomass is 0.2. If the number of rabbits doubles and the number of foxes also doubles, the number of rabbits that are killed will

d. quadruple.

Suppose that the relative proportion of susceptible and infected individuals in a population remains the same, but the density of the overall population doubles. According to the SI model, disease transmission should

d. quadruple.

Kraaijeveld and colleagues performed studies with Drosophila strains that can mount an encapsulation defense. In the absence of encapsulation, wasp eggs that have the ability to avoid encapsulation hatch _______ other eggs that cannot avoid encapsulation. These studies demonstrate _______.

d. slower than; the existence of trade-offs