Question 1

Some Aleutian Islands are surrounded by urchin barrens while others are surrounded by kelp forests. Which statement gives the primary explanation for these differences?
A) Kelp forest islands and urchin barren islands differ with respect to oceanic currents.
B) Kelp eat urchins, thus preventing their establishment.
C) The kelp forest islands experience a substantially warmer climate than do the urchin barren islands.
D) Grazing by urchins prevents the formation of kelp forests.

Accepted Answer

Grazing by urchins prevents the formation of kelp forests, as urchins consume the kelp, leading to the formation of urchin barrens.

Question 2

Which statement about Duggins's urchin removal experiments is true?
A) Kelp was abundant in both the urchin-excluded and the control treatments at the start of the experiments.
B) Kelp did not become established in the control treatment.
C) Kelp did not become established in the urchin-excluded treatment.
D) Urchins died in the control treatment due to the presence of kelp.

Accepted Answer

Kelp did not become established in the control treatment because the presence of urchins prevented its growth.

Question 3

Refer to the figure.
 Assume that the number of individuals of Laminaria is on a linear trajectory in the figure. If Duggins had sampled the kelp density 1.5 years after urchin removal, predict the approximate number of individuals of Laminaria he would have counted.
A) 20
B) 40
C) 60
D) 100

Accepted Answer

C

Question 4

Which statement about populations is false?
A) The distribution of a species is the geographic area where the abundance of the species is greater than zero.
B) Populations are dynamic entities that vary in size over time and space.
C) A population is a group of individuals from the same species that interact with one another within a particular area.
D) Populations are all of the species in an area that are capable of interacting.

Accepted Answer

Populations refer to groups of individuals of the same species in a specific area, not all species capable of interacting.

Question 5

There are 80 swamp sparrows in a 20-hectare section of Mount Meadow. The average population density of sparrows at this site is _______ per hectare.
A) 4
B) 20
C) 80
D) 160

Accepted Answer

The average population density is calculated by dividing the total number of sparrows by the total area in hectares. So, 80 sparrows / 20 hectares = 4 sparrows per hectare.

Question 6

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?
A) 15
B) 45
C) 225
D) 1,500

Accepted Answer

The area is 5 km * 3 km = 15 square kilometers. With a density of 15 plants per square kilometer, the expected number of plants is 15 * 15 = 225.

Question 7

Which statement about populations is false?
A) If little is known about the distance that sexually reproducing organisms or their gametes move, the area that constitutes a single population is difficult to estimate.
B) Population abundances change over time and space.
C) A population may consist of a series of patches of individuals that are isolated in space but are connected by dispersal.
D) Most organisms have similar capacities for dispersal.

Accepted Answer

Different organisms have varying capacities for dispersal due to differences in their physical characteristics, behaviors, and environmental interactions.

Question 8

King's Lomatia (Lomatia tasmanica) is a most unusual plant. In the wild, only a single genetic individual of this shrub is known to be alive, and this colony has existed for at least 40,000 years. When a branch of this shrub falls to the ground, it sometimes establishes roots, and thus can function as a physiologically independent plant that is genetically identical to all other plants in the colony.
- What is the technical term for the single genetic individual?
A) Biotic
B) Gamete
C) Ramet
D) Genet

Accepted Answer

A "genet" is the term used to describe a single genetic individual in a population of clonal organisms.

Question 9

King's Lomatia (Lomatia tasmanica) is a most unusual plant. In the wild, only a single genetic individual of this shrub is known to be alive, and this colony has existed for at least 40,000 years. When a branch of this shrub falls to the ground, it sometimes establishes roots, and thus can function as a physiologically independent plant that is genetically identical to all other plants in the colony.
- Which term refers to a clone that is a physiologically independent plant?
A) Biotic
B) Gamete
C) Ramet
D) Genet

Accepted Answer

A ramet is a physiologically independent plant that is genetically identical to all other plants in the colony.

Question 10

An evolutionary ecologist is studying the evolutionary change in populations of lizards that reproduce via parthenogenesis. How do these individuals form?
A) Budding
B) Apomixis
C) Horizontal spread
D) Random sexual mating

Accepted Answer

The answer of An evolutionary ecologist is studying the evolutionary...

Question 11

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?
A) Comparisons of area counts
B) Mark-release studies
C) Comparisons of the number of tracks made by each species
D) Quadrat sampling

Accepted Answer

Comparisons of the number of tracks made by each species provide relative estimates of population densities, as they indicate the presence and activity levels of each species rather than their exact numbers.

Question 12

Area-based methods often make use of sampling areas of a defined size called
A) GARPs.
B) quadrats.
C) transects.
D) ramets.

Accepted Answer

Quadrats are defined areas of a specific size that are used to sample vegetation in area-based methods.

Question 13

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?
A) Area-based counts
B) Point sampling
C) Line transects
D) Mark-recapture

Accepted Answer

Mark-recapture is a method used to estimate population size and study movement patterns by capturing, marking, releasing, and recapturing individuals.

Question 14

Point sampling is a type of
A) area-based count.
B) distance method.
C) detection function.
D) mark-recapture study.

Accepted Answer

Point sampling is a type of distance method used to estimate the abundance or density of a population by measuring distances from random points to detected individuals.

Question 15

Suppose that a team of biologists wishes to estimate the population numbers of endangered lizards by means of line transects. Since distant lizards are difficult to see, the biologists will most likely use which method?
A) Niche modeling
B) Mark-recapture
C) Area-based counts
D) A detection function

Accepted Answer

A detection function is used in line transect sampling to account for the decreasing probability of detecting an individual as the distance from the transect line increases.

Question 16

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
A) 360.
B) 450.
C) 600.
D) 720.

Accepted Answer

The answer of In a mark-recapture study to estimate the...

Question 17

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?
A) 80
B) 2,000
C) 3,000
D) 8,000

Accepted Answer

The average number of moths per quadrat is (10+20+35+15)/4 = 20. The total area is 150 square meters, so the estimate is 20 moths/square meter * 150 square meters = 3,000 moths.

Question 18

Individuals of a plant species are counted in five transects that are each 2 * 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
B) 10
C) 15
D) 20

Accepted Answer

The total number of plants is 8 + 15 + 19 + 27 + 31 = 100. The total area of the transects is 5 * 20 = 100 square meters. Therefore, the density is 100 plants / 100 square meters = 1 plant per square meter.

Question 19

A researcher studying apple maggot flies marks 180 flies in an orchid in Michigan. The next day, she collects 70 flies and finds that 14 are marked. If the assumptions of the mark-recapture method are met, what is the best estimate for the number of apple maggot flies in that orchid?
A) 180
B) 900
C) 980
D) 1,800

Accepted Answer

The mark-recapture method estimates population size using the formula: (number of marked individuals in the first sample * total number of individuals in the second sample) / number of marked individuals recaptured. Here, (180 * 70) / 14 = 900.

Question 20

Which statement is not an assumption of the mark-recapture method of estimating population size?
A) No individuals are born between the first and second captures.
B) No individuals die between the first and second captures.
C) Individuals do not move into or out of the study site between the first and second captures.
D) All marked individuals must be recaptured as well as additional unmarked individuals for accurate estimates.

Accepted Answer

The mark-recapture method does not require that all marked individuals be recaptured; it relies on a proportion of marked to unmarked individuals to estimate population size.

Quiz 9: Population Distribution and Abundance

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

Which statement about Duggins's urchin removal experiments is true?

Refer to the figure. Assume that the number of individuals of Laminaria is on a linear trajectory in the figure. If Duggins had sampled the kelp density 1.5 years after urchin removal, predict the approximate number of individuals of Laminaria he would have counted.

Which statement about populations is false?

There are 80 swamp sparrows in a 20-hectare section of Mount Meadow. The average population density of sparrows at this site is _______ per hectare.

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?

Which statement about populations is false?

An evolutionary ecologist is studying the evolutionary change in populations of lizards that reproduce via parthenogenesis. How do these individuals form?

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?

Area-based methods often make use of sampling areas of a defined size called

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?

Point sampling is a type of

Suppose that a team of biologists wishes to estimate the population numbers of endangered lizards by means of line transects. Since distant lizards are difficult to see, the biologists will most likely use which method?

Individuals of a plant species are counted in five transects that are each 2 * 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 researcher studying apple maggot flies marks 180 flies in an orchid in Michigan. The next day, she collects 70 flies and finds that 14 are marked. If the assumptions of the mark-recapture method are met, what is the best estimate for the number of apple maggot flies in that orchid?

Which statement is not an assumption of the mark-recapture method of estimating population size?