Question 1

At its earliest stages, a logistic growth curve closely resembles an exponential growth curve.

Accepted Answer

During the initial stages of logistic growth, the population size grows at a similar rate to exponential growth, but eventually levels off due to limiting factors such as resource availability and competition for resources.

Question 2

If you were a conservation biologist in charge of the recovery plans for an endangered species, which would you prefer to find within that species-an even distribution of age classes or a pyramid-shaped age distribution? Why?

Accepted Answer

A pyramid-shaped age distribution indicates a larger number of younger individuals, suggesting higher birth rates and potential for population growth, which is beneficial for the recovery of an endangered species.

Question 3

A scientist is studying a population of feral cats in his city. He notes that the r of this population is 1. What does this mean (assume he is evaluating population size on a yearly basis)?

Accepted Answer

In population ecology, r is the intrinsic rate of increase, which measures the potential rate of growth for a population under ideal conditions. An r value of 1 indicates that the population is growing at a rate of 100% per year, meaning it is doubling in size each year.

Question 4

In the experiments with moss patches described in your text, what were the two factors that affected insect extinction rates within patches?

Accepted Answer

Patch size and patch connectivity (usable habitat corridors between patches) are the two factors that significantly affect insect extinction rates within patches, as they directly influence the ability of species to sustain viable populations and disperse between habitat areas.

Question 5

A scientist is studying a population of feral cats in his city. After 10 years, he notes that for the population of feral cats he is studying, (K-N)/K = 0. Based on this information, what can he deduce about the logistic growth curve for the population at this point in time?

Accepted Answer

(K-N)/K = 0 indicates that the population size (N) has reached the carrying capacity (K), causing the growth rate to plateau. Therefore, the logistic growth curve has likely plateaued at K at this point in time.

Question 6

Consider the data in Figure 46.11 illustrating the survivorship curve of the lime swallowtail butterfly. As indicated in your text, the survivorship from the egg to larval stage is 68%. Calculate the survivorship from the larval to pupal stage. a.
$\begin{array} { l l l l } \text { Stage } & \text { Approximate duration } & \text { Number alive } & \text { Survivorship } \ \text { Egg } & 5 \text { days } & 250 & 0.68 \ \text { Larva } & 18 \text { days } & 170 & 0.93 \ \text { Pupa } & 15 \text { days } & 158 & 0.45 \ \text { Adult } & 5 \text { days } & 71 & \end{array}$
b.

Accepted Answer

According to the survivorship curve, the survivorship from the egg to larval stage is 68%. Therefore, the remaining 32% did not survive to the next stage. The survivorship from the larval to pupal stage can be calculated by taking the number of individuals that survived to the pupal stage divided by the number of individuals that were in the larval stage (i.e. 100 - 32 = 68 individuals). From the graph, we can see that approximately 93% (63/68) of individuals survived from the larval to pupal stage. Therefore, the answer is A) 93% (0.93).

Question 7

In the logistic growth curve depicted in Figure 46.6, as time goes on, what value would you expect N to approach?

Accepted Answer

As time goes on, the logistic growth curve approaches the carrying capacity (K) of the environment, which is the maximum number of individuals that can be supported by the available resources.

Question 8

When sea turtle eggs hatch, predators gather and mortality among the hatchlings is extremely high. Once turtles reach adult size, they can live for decades. This is an example of Type _____ survivorship.

Accepted Answer

Type III survivorship is characterized by high mortality rates in early life stages, such as sea turtle hatchlings facing numerous predators. However, those that survive to adulthood tend to have relatively long lifespans.

Question 9

Phylogenies suggest that Anolis lizards colonized Hispaniola:

Accepted Answer

Phylogenies, which are essentially evolutionary trees, suggest that Anolis lizards colonized Hispaniola five or six times. This is based on the genetic diversity and distribution of species across the island, indicating multiple colonization events rather than a single or few instances.

Question 10

An r-strategist will typically:

Accepted Answer

An r-strategist typically produces many small offspring with little to no parental care, focusing on high reproductive rates.

Question 11

In the 1940s, biologist Adolph Murie studied survival in Dall sheep in what is now Denali National Park in Alaska. He found that Dall sheep that survive their first year of life have a high probability of surviving until they are around 9 years old; after that, they rapidly become easy prey for wolves and die at a very high rate. This pattern BEST fits a Type _____ survivorship curve.

Accepted Answer

Type I survivorship curves are characterized by high survival rates of the young, with a significant drop in survival for older age groups, which matches the pattern observed in Dall sheep by Adolph Murie.

Question 12

The figure below illustrates a life-history trade-off between survivorship and reproduction in red deer from the Isle of Rhum in northern Scotland.  At what age is this trade-off minimized (i.e., at what age is the cost of reproduction LOWEST)?

Accepted Answer

The trade-off between survivorship and reproduction is lowest at 8 years of age, where the survival rate is highest and the reproductive output is relatively high. At younger ages, individuals allocate more resources towards growth and survival, while at older ages, individuals invest more in reproduction at the cost of survival.

Question 13

Giant clams synchronize their reproduction with the phases of the moon. During these reproductive bouts a single clam can release approximately 500 million eggs to be fertilized in the water column by sperm released from other clams. However, the population sizes of giant clams are very low because many of the fertilized eggs and larvae will be eaten by fish in the local area. Based on this information, what can be said of the reproductive strategy of the giant clam?

Accepted Answer

Giant clams exhibit an r-strategist reproductive strategy, characterized by the production of a high number of offspring with the expectation that only a few will survive to adulthood. This is evident from their release of approximately 500 million eggs during reproduction, despite the high predation rates on fertilized eggs and larvae.

Question 14

Natural populations are affected by both density-dependent and density-independent factors. In a population affected mainly by density-independent factors, would you expect natural selection to favor an r-selected or K-selected life history?

Accepted Answer

In a population affected mainly by density-independent factors, population growth is unpredictable and unstable, with sudden booms and busts. This favors organisms with an r-selected life history, which prioritize rapid reproduction and high population growth rates over individual survival and parental care. These traits allow r-selected species to quickly take advantage of favorable conditions and rebound from population crashes. K-selected species, on the other hand, invest heavily in individual survival and parental care, but have slower population growth rates and are less able to bounce back from sudden population declines.

Question 15

Consider the data in Figure 46.11 illustrating the survivorship curve of the lime swallowtail butterfly. As indicated in your text, the survivorship from the egg to larval stage is 68%. Calculate the survivorship from the egg to adult stage. a.
$\begin{array} { l l l l } \text { Stage } & \text { Approximate duration } & \text { Number alive } & \text { Survivorship } \ \text { Egg } & 5 \text { days } & 250 & 0.68 \ \text { Larva } & 18 \text { days } & 170 & 0.93 \ \text { Pupa } & 15 \text { days } & 158 & 0.45 \ \text { Adult } & 5 \text { days } & 71 & \end{array}$
b.

Accepted Answer

The answer of Consider the data in Figure 46.11 illustrating...

Question 16

If having large numbers of offspring results in high fitness, why don't all females have very large numbers of offspring?

Accepted Answer

Females are limited by the amount of energy they can devote to reproduction in any one season. Producing and raising offspring requires significant amounts of energy and resources, so females must balance the number of offspring they produce with their ability to care for them and allocate enough resources to their own survival. In addition, some species have limited resources or unpredictable environments, which further limits the number of offspring that can be produced.

Question 17

The following age pyramid was determined from a population.  What can be stated about the population?

Accepted Answer

The answer of The following age pyramid was determined from...

Question 18

Consider the data in Figure 46.8 illustrating the age structure of France and India.  In many parts of the world, the average age of reproductive maturity is increasing as humans move from urban to rural environments. Suppose that the current average age of first reproduction is 15 years old in India and 20 years old in France. How would a 5-year increase in the average age of reproductive maturity in both countries be expected to affect the per capita birth rate, and would this effect be greater in France or in India?

Accepted Answer

A 5-year increase in the average age of reproductive maturity is expected to decrease the per capita birth rate in both countries, but it would have a greater effect in France because the proportion of individuals of reproductive age is already smaller compared to India. As the age of first reproduction increases, individuals are likely to have fewer children, resulting in a decrease in the per capita birth rate.

Question 19

Consider the data in Figure 46.11 illustrating the survivorship curve of the lime swallowtail butterfly. As indicated in your text, the survivorship from the egg to larval stage is 68%. Calculate the survivorship from the egg to pupal stage. a.
$\begin{array} { l l l l } \text { Stage } & \text { Approximate duration } & \text { Number alive } & \text { Survivorship } \ \text { Egg } & 5 \text { days } & 250 & 0.68 \ \text { Larva } & 18 \text { days } & 170 & 0.93 \ \text { Pupa } & 15 \text { days } & 158 & 0.45 \ \text { Adult } & 5 \text { days } & 71 & \end{array}$
b.

Accepted Answer

The answer of Consider the data in Figure 46.11 illustrating...

Question 20

A K-strategist will typically:

Accepted Answer

K-strategists typically produce fewer, larger offspring and invest significantly in parental care to ensure the survival and success of those offspring. This strategy contrasts with r-strategists, which produce many small offspring with minimal parental care.

Quiz 46: Population Ecology

At its earliest stages, a logistic growth curve closely resembles an exponential growth curve.

If you were a conservation biologist in charge of the recovery plans for an endangered species, which would you prefer to find within that species-an even distribution of age classes or a pyramid-shaped age distribution? Why?

A scientist is studying a population of feral cats in his city. He notes that the r of this population is 1. What does this mean (assume he is evaluating population size on a yearly basis) ?

In the experiments with moss patches described in your text, what were the two factors that affected insect extinction rates within patches?

A scientist is studying a population of feral cats in his city. After 10 years, he notes that for the population of feral cats he is studying, (K-N) /K = 0. Based on this information, what can he deduce about the logistic growth curve for the population at this point in time?

In the logistic growth curve depicted in Figure 46.6, as time goes on, what value would you expect N to approach? $In the logistic growth curve depicted in Figure 46.6, as time goes on, what value would you expect N to approach? A) r B) K C) S D) t E) \Delta N$