Question 1

The Shannon index of species diversity is calculated using this equation:  Habitat A has a total of 100 birds, with the following numbers of individuals per species: 20, 25, 20, 15, and 20.Habitat B also has 100 birds, with the following numbers of individuals per species: 80, 5, 5, 5, and 5.Based on the Shannon indices for habitats A and B, which habitat (if either) has a higher species diversity?

Accepted Answer

The answer of The Shannon index of species diversity is...

Question 2

An animal species has the potential to become a member of a natural community forming in an area that is recovering from a massive hurricane.To become established in the new community, the first requirement is that the species must be able to

Accepted Answer

For a species to become established in a new community, especially one recovering from a disturbance like a massive hurricane, the first and foremost requirement is the ability to disperse into the new habitat. Without reaching the new area, no other interactions or adaptations can occur.

Question 3

The Shannon index of species diversity is calculated using this equation:  Habitat A has a total of 100 birds, with the following numbers of individuals per species: 20, 25, 20, 15, and 20.Habitat B also has 100 birds, with the following numbers of individuals per species: 80, 5, 5, 5, and 5.What is the Shannon index for habitat B?

Accepted Answer

For habitat B, 
- Species 1: Relative abundance = 0.8
- Species 2-5: Relative abundance = 0.05 (each)

Therefore, applying the Shannon diversity index equation:

-(-0.8*log2(0.8) - 4*0.05*log2(0.05)) = 0.78

Thus, the Shannon index for habitat B is 0.78.

Question 4

A non-native fish species is accidentally introduced into a tropical river.It appears to be well adapted to its new river environment.However, it feeds on smaller fish and is less aggressive than native fish species, so it has difficulty competing and eventually dies out.This species' failure to become a member of the new community is due to which factor(s)?

Accepted Answer

The non-native fish species failed to become a member of the new community due to species interactions, which includes competition with native fish species for food resources. Although the non-native species was well-adapted to the environmental conditions of the tropical river, its inability to compete with native fish species eventually led to its extinction in the new community. Dispersal, or the movement of individuals or populations from one area to another, may have initially brought the non-native fish species to the tropical river, but it was not the main factor leading to its failure. Environmental conditions likely played a role in the success of the non-native fish species at first, but its inability to compete with native fish species was the primary factor in its eventual demise. Therefore, the best choice is B, species interactions.

Question 5

In what way is an invasive species most likely to harm the community it invades?

Accepted Answer

Invasive species often outcompete native species for resources such as food, water, and habitat, leading to a decline in the native species' populations. This can lead to a disruption in the balance of the ecosystem and ultimately harm the community as a whole.

Question 6

Species composition was analyzed for fish communities in two Brazilian rivers.The higher (headwaters), middle, and lower (floodplain) sections of both the Iguatemi River and the Jogui River were sampled.The Iguatemi had 34 species and the Jogui had 31.In both rivers, some species occurred only in the headwaters, others only in the floodplains.Water velocity decreased and turbidity increased from the headwaters to the floodplains.Neither river had rooted vegetation, and the communities did not differ significantly from season to season.The factor most important in determining species composition in the two rivers was most likely

Accepted Answer

The fact that some species occurred only in the headwaters and others only in the floodplains suggests that changing characteristics from headwaters to floodplains is an important factor in determining species composition in the two rivers. Water velocity and turbidity were noted as changing, and the lack of rooted vegetation suggests that this factor was not significant. Temperature and the presence of endangered species were not mentioned as relevant factors, and while richness of fish species was noted, it is not clear from the information given whether this was a determining factor in species composition.

Question 7

At one time, giant African land snails were sold as pets, for teaching purposes, and for food.However, this snail has become a serious pest in habitats around the world.It carries plant pathogens, competes with native snails, eats 500 different species of plants, and even spreads human disease.The least likely way this invasive snail could have entered ecosystems in the United States is by

Accepted Answer

It is highly unlikely that the giant African land snail could have entered ecosystems in the United States by deliberate swimming from its home in Africa. This is because snails are not capable of swimming across the Atlantic Ocean, which is the body of water that separates Africa from the United States.

Question 8

In comparing the terms "species diversity" and "biodiversity," it would be most correct to say that

Accepted Answer

"Species diversity" specifically refers to the number of different species in a community, while "biodiversity" is a broader term that can encompass diversity at the genetic level, as well as entire ecosystems and the interactions between different species. Therefore, B is the most correct answer.

Question 9

Coral reefs are found in shallow, coastal, tropical waters.Many species of organisms that might fit well in a coral reef community live some distance away.Which of these organisms would be most likely to colonize the coral reef?

Accepted Answer

A species that is sessile as an adult but has a free-floating larval stage would be most likely to colonize the coral reef as it has the capability to travel some distance and settle in a new location. Additionally, the larval stage can potentially avoid predators and unfavorable conditions by floating with ocean currents.

Question 10

An ecologist studying the community within the canopy of a rainforest tree constructs a food web of the canopy community.By simply observing the connections in this food web, the ecologist will gain insight into which aspect of the community?

Accepted Answer

The food web visually represents the feeding relationships within a community, showing the direction of energy flow from one organism to another, but it does not quantitatively measure amounts, rates, or percentages of energy or nutrient flows.

Question 11

The Shannon index of species diversity is calculated using this equation:  Habitat A has a total of 100 birds, with the following numbers of individuals per species: 20, 25, 20, 15, and 20.Habitat B also has 100 birds, with the following numbers of individuals per species: 80, 5, 5, 5, and 5.What is the Shannon index for habitat A?

Accepted Answer

The answer of The Shannon index of species diversity is...

Question 12

In the Shannon index, the mathematical calculation of species diversity, H, incorporates measurements of

Accepted Answer

The Shannon index H takes into account both species richness and evenness. Species richness is measured as the number of different species present, while evenness refers to how evenly each species is represented. Evenness can be measured as the proportion of individuals in each species relative to the total number of individuals. Therefore, choice E is the best answer.

Question 13

High species diversity, considered a positive attribute of a community, is measured by both species richness and species evenness.How would higher species evenness likely act as a positive factor in the community?

Accepted Answer

Higher species evenness means that the number of individuals of each species is similar. This would reduce the dominance of any one species, and may decrease the risk of extinction of any one species.

Question 14

Ecologists want to understand ecological changes as a forested area is cut and then begins to recover.They measure the number and evenness of species present at the beginning (before cutting) and at different times after cutting.They are measuring changes in which ecological characteristic?

Accepted Answer

They are measuring species diversity, which includes both the number of species (species richness) and the evenness of their distribution.

Question 15

Refer to the figure.  Compare the samples of frogs in the two communities.Assume that frogs that appear different are separate species.Compared to pond A, pond B has

Accepted Answer

The answer of Refer to the figure.  Compare the...

Question 16

A food web is generally used to describe connections or interactions in an ecological community that are related to which factor?

Accepted Answer

A food web is a diagram that shows the flow of energy from one organism to another within an ecosystem. It describes how energy is transferred from producers to consumers and then between different levels of consumers. Therefore, a food web is generally used to describe connections or interactions in an ecological community that are related to energy flow.

Question 17

Refer to the figure.   In which list are organisms ordered correctly from lowest to highest trophic level, according to the figure?

Accepted Answer

The answer of Refer to the figure.   In...

Question 18

A semiarid ecosystem is dominated by a mixture of shortgrass prairies and chaparral.Prairie primary producers include grasses and other herbaceous flowering plants (forbs).The chaparral is dominated by shrubs, including mesquite and yucca intermixed with grasses and forbs.Herbivores (jackrabbits and cottontails) in turn are eaten by "mesopredators," including badgers, bobcats, skunks, and gray foxes.The top-level predator is the coyote.How many trophic levels are described in this ecosystem?

Accepted Answer

The ecosystem described has four trophic levels - primary producers (grasses and forbs), herbivores (jackrabbits and cottontails), mesopredators (badgers, bobcats, skunks, and gray foxes), and the top-level predator (coyote).

Question 19

The regional species pool of a community defines the conditions for a species to

Accepted Answer

The regional species pool defines the conditions for a species to disperse into the community, meaning it determines whether or not a species is present or absent from the community. It does not affect how a species lives or adapts to its environment within the community.

Question 20

The West Nile virus is carried by invasive Asian tiger mosquitoes and can infect humans.The Dutch elm fungus, spread by the invasive European elm bark beetle, as well as other elm bark beetles, has devastated elm tree populations in the northern United States.These two invasive species are similar in that both

Accepted Answer

Both the Asian tiger mosquito and the European elm bark beetle are vectors that spread diseases; the former spreads the West Nile virus, and the latter spreads the Dutch elm fungus.

Quiz 56: Communities