Deck 37: Ecosystems

Question 1

Are Island Populations of Song Sparrows Density Dependent
When island populations are isolated, receiving no visitors from other populations, they provide an attractive opportunity to test the degree to which a population s growth rate is affected by its size. A population s size can influence the rate at which it grows because increased numbers of individuals within a population tend to deplete available resources, leading to an increased risk of death by deprivation. Also, predators tend to focus their attention on common prey, resulting in increasing rates of mortality as populations grow. However, simply knowing that a population is decreasing in numbers does not tell you that the decrease has been caused by the size of the population. Many factors such as severe weather, volcanic eruption, and human disturbance can influence island population sizes too.
The graph to the right displays data collected from 13 song sparrow populations on Mandarte Island (see map below). In an attempt to gauge the impact of population size on the evolutionary success of these populations, each population was censused, and its juvenile mortality rate estimated. On the graph, these juvenile mortality rates have been plotted against the number of breeding adults in each population. Although the data appear scattered, the "best-fit" regression line is statistically significant (statistically significant means that there is a less than 5% chance that there is in fact no correlation between dependent and independent variables).

Applying Concepts
a. Variable. In the graph, what is the dependent variable
b. Analyzing Scattered Data. What is the size of the song sparrow population (based on breeding adults) with the least juvenile mortality with the most

Answer 1

Population of any area is dependent on variable factors. If the number of predators is low and the number of resources is more, the population of that area increases. But with an increase in the number of individuals, the population gradually decreases. This reduction is due to the competition by other individuals.
a.
The graph shows the effects of population size on songbird success. The graph represents the juvenile mortality in relation to the number of breeding adults. The juvenile mortality is based on the number of breeding adults. Therefore, the juvenile mortality is the dependent variable.
b.
The size of the sparrow population with the least juvenile mortality is 18. The juvenile mortality with this population was 0.52. The size of the sparrow population with the most juvenile mortality is 140. The juvenile mortality with this population was 0.90.

Question 2

A relationship between two species where one species benefits and the other is neither hurt nor helped is known as
a. parasitism.
b. commensalism.
c. mutualism.
d. competition.

Answer 2

NO ANSWER

Question 3

When the number of organisms in a population remains more or less the same over time in the specific place where these organisms live, it is said that this population of organisms has reached the _________of that place.
a. dispersion
b. biotic potential
c. carrying capacity
d. population density

Answer 3

NO ANSWER

Question 4

Predators can assist in maintaining the species diversity of an area by
a. increasing competitive exclusion between prey species.
b. decreasing competitive exclusion between prey species.
c. not affecting competitive exclusion between prey species.
d. decreasing resource partitioning between prey species.

Question 5

Figure 37.2 Speculate on what happens with populations that follow the exponential growth model.

Question 6

The bright colors of poison-dart frogs and Gila monsters are examples of
a. aposematic coloration.
b. Müllerian mimicry.
c. cryptic coloration.
d. Batesian mimicry.

Question 7

Use the terms from this section, interspecific competition, fundamental niche, realized niche, niche overlap, competitive exclusion, and resource partitioning, to discuss Robert MacArthur's warbler research.

Question 8

Succession that occurs on abandoned agricultural fields is best described as
a. coevolution.
b. primary succession.
c. secondary succession.
d. prairie succession.

Question 9

Are Island Populations of Song Sparrows Density Dependent
When island populations are isolated, receiving no visitors from other populations, they provide an attractive opportunity to test the degree to which a population s growth rate is affected by its size. A population s size can influence the rate at which it grows because increased numbers of individuals within a population tend to deplete available resources, leading to an increased risk of death by deprivation. Also, predators tend to focus their attention on common prey, resulting in increasing rates of mortality as populations grow. However, simply knowing that a population is decreasing in numbers does not tell you that the decrease has been caused by the size of the population. Many factors such as severe weather, volcanic eruption, and human disturbance can influence island population sizes too.
The graph to the right displays data collected from 13 song sparrow populations on Mandarte Island (see map below). In an attempt to gauge the impact of population size on the evolutionary success of these populations, each population was censused, and its juvenile mortality rate estimated. On the graph, these juvenile mortality rates have been plotted against the number of breeding adults in each population. Although the data appear scattered, the "best-fit" regression line is statistically significant (statistically significant means that there is a less than 5% chance that there is in fact no correlation between dependent and independent variables).

Interpreting Data
a. What is the average juvenile mortality of all 13 populations, estimated from the 13 points on the graph
b. How many populations were observed to have juvenile mortality rates below this average value What is the average size of these populations
c. How many populations were observed to have juvenile mortality rates above this average value What is the average size of these populations

Question 10

Which of the following is a density-dependent effect on a population
a. earthquake
b. increased competition for food
c. habitat destruction by humans
d. seasonal flooding

Question 11

Figure 37.9 How would the niche change for Chthamalus if Semibalanus was removed from the community How would the niche change for Semibalanus if Chthamalus was removed from the community

Question 12

Briefly discuss and give examples of the three types of symbiosis.

Question 13

Are Island Populations of Song Sparrows Density Dependent
When island populations are isolated, receiving no visitors from other populations, they provide an attractive opportunity to test the degree to which a population s growth rate is affected by its size. A population s size can influence the rate at which it grows because increased numbers of individuals within a population tend to deplete available resources, leading to an increased risk of death by deprivation. Also, predators tend to focus their attention on common prey, resulting in increasing rates of mortality as populations grow. However, simply knowing that a population is decreasing in numbers does not tell you that the decrease has been caused by the size of the population. Many factors such as severe weather, volcanic eruption, and human disturbance can influence island population sizes too.
The graph to the right displays data collected from 13 song sparrow populations on Mandarte Island (see map below). In an attempt to gauge the impact of population size on the evolutionary success of these populations, each population was censused, and its juvenile mortality rate estimated. On the graph, these juvenile mortality rates have been plotted against the number of breeding adults in each population. Although the data appear scattered, the "best-fit" regression line is statistically significant (statistically significant means that there is a less than 5% chance that there is in fact no correlation between dependent and independent variables).

Making Inferences Are the populations with lower juvenile mortality bigger or smaller than the populations with higher juvenile mortality

Question 14

Which of the following traits is not a characteristic of an organism that has K -selected adaptations

A) short life span
B) few offspring per breeding season
C) extensive parental care of offspring
D) low mortality rate

Question 15

Many U.S. communities struggle with issues of deer overpopulation. Explain how human activities have created this situation.

Question 16

Are Island Populations of Song Sparrows Density Dependent
When island populations are isolated, receiving no visitors from other populations, they provide an attractive opportunity to test the degree to which a population s growth rate is affected by its size. A population s size can influence the rate at which it grows because increased numbers of individuals within a population tend to deplete available resources, leading to an increased risk of death by deprivation. Also, predators tend to focus their attention on common prey, resulting in increasing rates of mortality as populations grow. However, simply knowing that a population is decreasing in numbers does not tell you that the decrease has been caused by the size of the population. Many factors such as severe weather, volcanic eruption, and human disturbance can influence island population sizes too.
The graph to the right displays data collected from 13 song sparrow populations on Mandarte Island (see map below). In an attempt to gauge the impact of population size on the evolutionary success of these populations, each population was censused, and its juvenile mortality rate estimated. On the graph, these juvenile mortality rates have been plotted against the number of breeding adults in each population. Although the data appear scattered, the "best-fit" regression line is statistically significant (statistically significant means that there is a less than 5% chance that there is in fact no correlation between dependent and independent variables).

Drawing Conclusions Do the population sizes of these song sparrows appear to exhibit density dependence

Question 17

If the age structure of a population shows more older organisms than younger organisms, then the fecundity

A) will increase, and the mortality will decrease.
B) will decrease, and the mortality will increase.
C) and the mortality will be equal.
D) and the mortality will not change.

Question 18

Are Island Populations of Song Sparrows Density Dependent
When island populations are isolated, receiving no visitors from other populations, they provide an attractive opportunity to test the degree to which a population s growth rate is affected by its size. A population s size can influence the rate at which it grows because increased numbers of individuals within a population tend to deplete available resources, leading to an increased risk of death by deprivation. Also, predators tend to focus their attention on common prey, resulting in increasing rates of mortality as populations grow. However, simply knowing that a population is decreasing in numbers does not tell you that the decrease has been caused by the size of the population. Many factors such as severe weather, volcanic eruption, and human disturbance can influence island population sizes too.
The graph to the right displays data collected from 13 song sparrow populations on Mandarte Island (see map below). In an attempt to gauge the impact of population size on the evolutionary success of these populations, each population was censused, and its juvenile mortality rate estimated. On the graph, these juvenile mortality rates have been plotted against the number of breeding adults in each population. Although the data appear scattered, the "best-fit" regression line is statistically significant (statistically significant means that there is a less than 5% chance that there is in fact no correlation between dependent and independent variables).

Further Analysis
a. The fact that the song sparrow populations with lower juvenile mortality are a different size than those with higher juvenile mortality does not in itself establish that the difference is statistically significant. How would you go about testing these data to see if the relationship between juvenile mortality and population size is real
b. What would you expect to happen if the researchers supplemented the food available to the birds Explain.
c. What would you expect to happen if the researchers removed individuals from populations with more than 100 breeding adults, reducing each to 100

Question 19

All the animals and plants that live in the same location make up a(n)

A) biome.
B) population.
C) ecosystem.
D) community.

Question 20

Give at least two examples, from your own area, of limiting factors on a population that are density-dependent factors, and two that are density-independent factors on the same population.

Question 21

For similar species to occupy the same space, their niches must be different in some way. One way for these species to both survive is

A) competitive exclusion.
B) interspecific competition.
C) resource partitioning.
D) intraspecific competition.