Question 1

Negative density dependence occurs when the

Accepted Answer

A)  per capita population growth rate increases as population becomes larger. 
B)  per capita population growth rate remains constant as population becomes larger. 
C)  per capita population growth rate decreases as population becomes larger. 
D)  population increases without limit. 
E)  population decreases until it becomes extinct. 
A)  per capita population growth rate increases as population becomes larger. 
B)  per capita population growth rate remains constant as population becomes larger. 
C)  per capita population growth rate decreases as population becomes larger. 
D)  population increases without limit. 
E)  population decreases until it becomes extinct. C

Question 2

Consider a perennial plant with four life stages: seed, seedling, small adult, and large adult. Seeds survive to seedlings with a probability of 50 percent; seedlings survive to be small adults with a probability of 20 percent; small adults survive to be large adults with a probability of 20 percent. Both small adults and large adults produce an average of 10 seeds. Use this information to fill in the life table that follows; then calculate the R0 and explain whether the population is increasing, stable, or decreasing.

$$\begin{array} { | l | l | l | l | } 
\hline \text { Age Class } ( x ) & \text { Survival Rate } \left( \mathrm { s } _ { \mathrm { x } } \right) & \text { Survivorship } \left( \mathrm { l } _ { \mathrm { x } } \right) & \text { Fecundity } \left( \mathrm { b } _ { \mathrm { x } } \right) \
\hline \text { Seed } & & & \
\hline \text { Seedling } & & & \
\hline \text { Small adult } & & & \
\hline \text { Large adult } & & & \
\hline
\end{array}$$
R0: _____________________

Accepted Answer

$$\begin{array} { | l | l | l | l | } \hline \text { Age Class } ( x ) & \text { Survival Rate } \left( \mathrm { s } _ { \mathrm { x } } \right) & \text { Survivorship } \left( \mathrm { l } _ { \mathrm { x } } \right) & \text { Fecundity } \left( \mathrm { b } _ { \mathrm { x } } \right) \\hline \text { Seed } & 0.5 & 1 & 0 \\hline \text { Seedling } & 0.2 & 0.5 & 0 \\hline \text { Small adult } & 0.2 & 0.1 & 10 \\hline \text { Large adult } & 1 & 0.02 & 10 \\hline\end{array}$$

To calculate R0, we use the formula:

$$ R_0 = \sum_{x=0}^{\infty} l_x b_x $$

Where:
- $ l_x $ = Survivorship at age x
- $ b_x $ = Fecundity at age x

Using the values from the life table:

$$ R_0 = (1 \times 0) + (0.5 \times 0) + (0.1 \times 10) + (0.02 \times 10) = 0 + 0 + 1 + 0.2 = 1.2 $$

Since R0 is greater than 1, the population is increasing.

Question 3

Which plot is consistent with an exponential growth model when r > 0?

Accepted Answer

A)  a 
B)  b 
C)  c 
D)  d 
A)  a 
B)  b 
C)  c 
D)  d C

Question 4

When a population has a stable age distribution,

Accepted Answer

A)  the total number of individuals stays constant over time. 
B)  the proportion of individuals in each age class remains constant. 
C)  the net reproductive rate is less than one. 
D)  it is at its carrying capacity. 
A)  the total number of individuals stays constant over time. 
B)  the proportion of individuals in each age class remains constant. 
C)  the net reproductive rate is less than one. 
D)  it is at its carrying capacity.

Question 5

An age structure graph that appears rectangular in overall shape would likely see what in the future?

Accepted Answer

A)  an increase in population size 
B)  a decrease in population size 
C)  an increase, followed by a decrease in population size 
D)  no change in population size 
A)  an increase in population size 
B)  a decrease in population size 
C)  an increase, followed by a decrease in population size 
D)  no change in population size

Question 6

Which illustrates a negative relationship between population density and the average size of individuals over time?

Accepted Answer

A)  an exponential growth curve 
B)  a J-shaped curve 
C)  a survivorship curve 
D)  a self-thinning curve 
A)  an exponential growth curve 
B)  a J-shaped curve 
C)  a survivorship curve 
D)  a self-thinning curve

Question 7

Explain the difference between positive density dependence and negative density dependence.

Accepted Answer

Positive density dependence and negative

Question 8

Which accurately describes the inflection point in the logistic growth model?
I. Population growth slows after the inflection point.
II. The inflection point is equal to the carrying capacity.
III. The highest growth rate occurs at the inflection point.

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  I and III 
A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  I and III

Question 9

In the logistic growth model, in which of the following conditions is the overall rate of increase the highest?

Accepted Answer

A)  N = K 
B)  N = $\frac { K } { 2 }$ 
C)  N = $\frac { K } { 4 }$ 
D)  N = K + r 
A)  N = K 
B)  N = $\frac { K } { 2 }$ 
C)  N = $\frac { K } { 4 }$ 
D)  N = K + r

Question 10

A biologist grew 10 groups of flowers in 1-square-meter plots of soil. In five plots, the biologist planted 20 flowers, and in the other five plots, the biologist planted 100 flowers. At the end of the summer, the biologist counted the seeds that each flower produced and found 100 seeds per plant in the plot with 20 plants and 500 seeds per plant in the plot with 100 plants. This is an example of

Accepted Answer

A)  density-independent population regulation. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  a self-thinning curve. 
A)  density-independent population regulation. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  a self-thinning curve.

Question 11

The larvae of a carnivorous species of salamander inhabit ponds. When the pond contains few larvae, they mostly eat small invertebrates and have a high survival rate. When there are many salamander larvae in a pond, the larvae will also cannibalize each other and have a low survival rate. This is an example of

Accepted Answer

A)  geometric growth. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  density-independent population regulation. 
A)  geometric growth. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  density-independent population regulation.

Question 12

Which is likely to follow an exponential increase in population size?
I. a population of mice that has consumed most of the food in its habitat
II. a small population of rats recently introduced to an island with many resources
III. bacteria recently placed on a new petri dish with suitable growth medium

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II only 
E)  II and III only 
A)  I only 
B)  II only 
C)  III only 
D)  I and II only 
E)  II and III only

Question 13

If a population has relatively few individuals in the young classes but many in the medium-aged and old classes, what can we conclude about population growth?

Accepted Answer

A)  The population is declining. 
B)  The population is growing. 
C)  The population is stable. 
D)  The population is below carrying capacity. 
A)  The population is declining. 
B)  The population is growing. 
C)  The population is stable. 
D)  The population is below carrying capacity.

Question 14

Which form of population growth results in an S-shaped curve?

Accepted Answer

A)  exponential growth 
B)  geometric growth 
C)  logistic growth 
D)  density-independent growth 
A)  exponential growth 
B)  geometric growth 
C)  logistic growth 
D)  density-independent growth

Question 15

Consider a biologist studying a population of deer. At the beginning of the year, there are 100 adult deer in the population. Over the course of the year, 15 adult deer die, and an additional 25 deer are born. What can we conclude about $\lambda$ for this year?

Accepted Answer

A)  $\lambda$  0 
D)  $\lambda$= 1 
E)  $\lambda$ > 1 
A)  $\lambda$  0 
D)  $\lambda$= 1 
E)  $\lambda$ > 1

Question 16

A biologist studies a population of birds for 25 years. Each year the biologist records the amount of rainfall and the density of birds (number of birds per 100 square meters). In addition, the biologist determines the survival rate for eggs laid that year. The biologist then plots egg survival rate against both rainfall (graph a) and density (graph b). In each plot the individual points represent the data for one year of the study. Based on these data, does this population of birds appear to be subject to positive density-dependent population regulation, negative density-dependent population regulation, or density-independent population regulation? As part of your answer, list the prediction for each type of population regulation and explain whether the data meet that prediction.

Accepted Answer

The answer of A biologist studies a population of birds...

Question 17

A species of louse (an external parasite) infests salmon. Researchers have found that the lice have difficulty finding a mate when there are only a few lice on an individual fish. The lice find mates more easily and produce more offspring when there are many lice on an individual fish. This is an example of

Accepted Answer

A)  the geometric growth model. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  density-independent population regulation. 
A)  the geometric growth model. 
B)  positive density-dependent population regulation. 
C)  negative density-dependent population regulation. 
D)  density-independent population regulation.

Question 18

In what way is the geometric growth model different from the exponential growth model?

Accepted Answer

A)  The geometric growth model uses continuous time. 
B)  The geometric growth model uses regular time intervals. 
C)  The geometric growth model includes carrying capacity (K). 
D)  The exponential growth model includes carrying capacity (K). 
A)  The geometric growth model uses continuous time. 
B)  The geometric growth model uses regular time intervals. 
C)  The geometric growth model includes carrying capacity (K). 
D)  The exponential growth model includes carrying capacity (K).

Question 19

According to the exponential growth model, which would reduce a population's doubling time?

Accepted Answer

A)  an increase in the initial population size 
B)  a decrease in the initial population size 
C)  an increase in the intrinsic growth rate 
D)  a decrease in the intrinsic growth rate 
A)  an increase in the initial population size 
B)  a decrease in the initial population size 
C)  an increase in the intrinsic growth rate 
D)  a decrease in the intrinsic growth rate

Question 20

For 5 years, a biologist studied a population of mice living in a field. The mice have three age classes: 1 year old, 2 years old, and 3 years old. The number of individuals in each age class over the course of the study is shown in the table. 
$$\begin{array} { | c | c | c | c | } 
\hline \begin{array} { c } 
\text { Age in } \
\text { Years } ( \mathrm { x } )
\end{array} & \begin{array} { c } 
\text { Survival Rate } \
\left( \mathrm { s } _ { \mathrm { x } } \right)
\end{array} & \begin{array} { c } 
\text { Survivorship } \
\left( \mathrm { l } _ { \mathrm { x } } \right)
\end{array} & \begin{array} { c } 
\text { Fecundity } \
\left( \mathrm { b } _ { \mathrm { x } } \right)
\end{array} \
\hline 1 & 0.1 & 1.0000 & \
\hline 2 & 0.8 & 0.1000 & \
\hline 3 & 0.8 & 0.0800 & \
\hline 4 & 0.8 & 0.0640 & 10 \
\hline 5 & & 0.0512 & 20 \
\hline
\end{array}$$

Accepted Answer

A) 	4 years 
B) 	4.6 years 
C) 	5 years 
D) 	7.7 years 
A) 	4 years 
B) 	4.6 years 
C) 	5 years 
D) 	7.7 years

Negative density dependence occurs when the

Which plot is consistent with an exponential growth model when r > 0?

When a population has a stable age distribution,

An age structure graph that appears rectangular in overall shape would likely see what in the future?

Which illustrates a negative relationship between population density and the average size of individuals over time?

Explain the difference between positive density dependence and negative density dependence.

Which accurately describes the inflection point in the logistic growth model? I. Population growth slows after the inflection point. II. The inflection point is equal to the carrying capacity. III. The highest growth rate occurs at the inflection point.

In the logistic growth model, in which of the following conditions is the overall rate of increase the highest?

If a population has relatively few individuals in the young classes but many in the medium-aged and old classes, what can we conclude about population growth?

Which form of population growth results in an S-shaped curve?

Consider a biologist studying a population of deer. At the beginning of the year, there are 100 adult deer in the population. Over the course of the year, 15 adult deer die, and an additional 25 deer are born. What can we conclude about $\lambda$ for this year?

In what way is the geometric growth model different from the exponential growth model?

According to the exponential growth model, which would reduce a population's doubling time?

Introduction: Ecology, Evolution, and the Scientific Method

Adaptations to Aquatic Environments

Adaptations to Terrestrial Environments

Adaptations to Variable Environments

Climates and Soils

Terrestrial and Aquatic Biomes

Evolution and Adaptation

Life Histories

Reproductive Strategies

Social Behaviors

Population Distributions

Population Dynamics Over Space and Time

Predation and Herbivory

Parasitism and Infectious Diseases

Competition

Mutualism

Community Structure

Community Succession

Movement of Energy in Ecosystems

Movement of Elements in Ecosystems

Landscape Ecology and Global Biodiversity

Global Conservation of Biodiversity

Filters

Exam 12: Population Growth and Regulation

Negative density dependence occurs when the

Which plot is consistent with an exponential growth model when r > 0?

When a population has a stable age distribution,

An age structure graph that appears rectangular in overall shape would likely see what in the future?

Which illustrates a negative relationship between population density and the average size of individuals over time?

Explain the difference between positive density dependence and negative density dependence.

Which accurately describes the inflection point in the logistic growth model? I. Population growth slows after the inflection point. II. The inflection point is equal to the carrying capacity. III. The highest growth rate occurs at the inflection point.

In the logistic growth model, in which of the following conditions is the overall rate of increase the highest?

If a population has relatively few individuals in the young classes but many in the medium-aged and old classes, what can we conclude about population growth?

Which form of population growth results in an S-shaped curve?

Consider a biologist studying a population of deer. At the beginning of the year, there are 100 adult deer in the population. Over the course of the year, 15 adult deer die, and an additional 25 deer are born. What can we conclude about λ\lambdaλ for this year?

In what way is the geometric growth model different from the exponential growth model?

According to the exponential growth model, which would reduce a population's doubling time?

Introduction: Ecology, Evolution, and the Scientific Method

Adaptations to Aquatic Environments

Adaptations to Terrestrial Environments

Adaptations to Variable Environments

Climates and Soils

Terrestrial and Aquatic Biomes

Evolution and Adaptation

Life Histories

Reproductive Strategies

Social Behaviors

Population Distributions

Population Dynamics Over Space and Time

Predation and Herbivory

Parasitism and Infectious Diseases

Competition

Mutualism

Community Structure

Community Succession

Movement of Energy in Ecosystems

Movement of Elements in Ecosystems

Landscape Ecology and Global Biodiversity

Global Conservation of Biodiversity

Filters

Consider a biologist studying a population of deer. At the beginning of the year, there are 100 adult deer in the population. Over the course of the year, 15 adult deer die, and an additional 25 deer are born. What can we conclude about $\lambda$ for this year?