Question 1

Which of the following explains what species richness is?

Accepted Answer

Species richness is defined as the number of different species present in a given community or ecosystem.

Question 2

In Figure 10.14b,which of the following statements is accurate?

Accepted Answer

In Figure 10.14b, the graph shows a positive association between the number of invertebrate taxa and mean stream pH between pH 5 to 7. Therefore, choice A is accurate. Choice B is incorrect as it suggests a negative association. Choice C is also incorrect as there is an association between the variables. Choice D is also incorrect as the graph does not provide evidence for this statement.

Question 3

Which of the following choices is a term that refers to diversity between communities?

Accepted Answer

Beta diversity refers to the diversity between communities, focusing on the differences in species composition between habitats or ecosystems.

Question 4

You are interested in comparing diversity between two different regions each with many communities.Which term would you use to describe this?

Accepted Answer

The answer of You are interested in comparing diversity between...

Question 5

Assume that resources for a community of species are available on a continuum.A common species of bird utilizes a particular portion of this continuum.What term defines the length of the portion of resources that this bird uses?

Accepted Answer

Niche breadth refers to the range of resources a species uses within its habitat. It is a measure of the breadth of the ecological niche of a species relative to the overall resource continuum.

Question 6

An organism has been discovered that appears to forego metabolizing phosphorous to instead metabolize arsenic.Phosphorous is essential to all living things.Why might this organism have evolved a way to metabolize arsenic in place of phosphorous?

Accepted Answer

The most likely explanation is that the organism evolved in an environment with a scarcity of phosphorous, or a high level of competition for this resource. In this environment, the ability to use arsenic may have provided a selective advantage, allowing the organism to survive and reproduce more successfully than other organisms that were reliant only on phosphorous. Over time, this trait became fixed in the population through natural selection. The other options (A, B and D) do not provide as convincing or likely explanations for this adaptation.

Question 7

You are assigned the task of determining species richness in a given area.The lead researcher has told you that the number of samples you have to take is not limited.As you collect data,what pattern should you expect to see?

Accepted Answer

This is because the most abundant species in the area will be easier to find and will likely be identified first. As more sampling is done, rarer and less obvious species will be discovered, increasing species richness overall. Option A and D are not accurate methods for determining species richness, and option B is incorrect as species richness tends to increase with more sampling, not decrease.

Question 8

Using a simple model of species richness based on a one dimensional continuum,what is one hypothetical way that species richness could increase?

Accepted Answer

If the range of resources in the community expands, more species can find suitable habitats and niches, thus increasing species richness.

Question 9

Species richness can be influenced by climatic factors that vary spatially.One hypothesis explains how environmental temperature may affect a community of organisms.Which hypothesis is this?

Accepted Answer

The energy hypothesis proposes that species richness is primarily determined by the amount of energy available in an ecosystem, and that energy availability is closely related to temperature. Therefore, this hypothesis would explain how environmental temperature may affect a community of organisms.

Question 10

Which of the following is a measure of atmospheric energy?

Accepted Answer

Potential evapotranspiration is a measure of the amount of energy available in the atmosphere to facilitate the movement of moisture into the air through evaporation and transpiration. It is often used as an indicator of the water availability and productivity of ecosystems. A, B, and D are not measures of atmospheric energy.

Question 11

You have assessed species richness in the tropics using 15 plots,each approximately 10 km by 10 km,spread over an entire region.Let us assume each plot is a community.Which of the following statements is likely correct?

Accepted Answer

High productivity in the tropics is often associated with high species richness. Therefore, the alpha diversity (species richness of individual plots) should be high. Additionally, since the plots are spread over an entire region, the gamma diversity (species richness of the entire region) may be higher than the alpha diversity, but it is not specified in the question.

Question 12

If a phylogenetic analysis shows that an assemblage of species is closely related,but only one of the species has evolved drastically different morphology that is known to be extremely costly,then why might this one species have evolved such a distinct trait?

Accepted Answer

The drastic and costly morphological change in the species likely evolved as an adaptation to survive in a much harsher environment compared to its relatives.

Question 13

Experiments performed in the rocky intertidal zone by Robert Paine showed that the experimental removal of a predator had dramatic consequences to the structure of the community.What was the ultimate conclusion of this study?

Accepted Answer

The ultimate conclusion of Robert Paine's study was that predators can mediate coexistence by reducing the number of individuals of a species in the community that tend to dominate and as a result increase species richness more than if they were not present.

Question 14

You are comparing species richness across 10 square meter plots over an entire region of Indiana.Your data show that individual communities are not diverse and that the communities in the region do not differ.Of the following choices,which is the best conclusion?

Accepted Answer

Gamma diversity refers to the overall diversity within a large region or landscape. If individual communities are not diverse and do not differ from each other, the overall regional diversity (gamma diversity) would be low.

Question 15

If you wanted to provide the most data for an audience about the species composition of a community and how it changes over time,which of the following would you use and why?

Accepted Answer

A rank-abundance diagram provides a comprehensive view of community structure by showing relative abundances of species, how these abundances change, the number of species present, and changes in species numbers over time, effectively illustrating species composition and its dynamics.

Question 16

In which of the two examples of a community is species richness greater: A community with 100 species that can all be found equally within a 25 km radius of the area,or a community spread across the same area that has 100 species,in which 5% of the individuals are rare species.

Accepted Answer

Species richness refers to the number of different species present in a community. Both communities have 100 species, so their species richness is the same, regardless of the distribution or rarity of individuals within those species.

Question 17

Deep sea communities of gastropods and bivalve mollusk species rely on which of the following as a resource?

Accepted Answer

Deep sea communities of gastropods and bivalve mollusks rely on particulate organic carbon as a resource. This carbon is produced by the decay and sinking of dead organic matter from surface waters.

Question 18

You have counted the number of amphibians and reptiles in the same experimental 1 km by 1 km area over the last five years.You also have a control plot of the same size nearby that is part of your sampling each year.Every year you have reviewed your data to understand which species were common or rare,and whether equal numbers of individuals were counted in those categories.What your data show is that in the experimental plot more species become rare to encounter and a large percentage of species that you do encounter tends to be more common from year one to year five.However,this is not the case in the control plot,which shows no change from year one to year five.You now plan to plot these data for a presentation.You now plan to plot these data for a presentation.What will a graph of rank-abundance for the control and non-control plots look like?

Accepted Answer

The description indicates that in the experimental plot, species become increasingly rare or common over time, suggesting a steepening trend in rank-abundance, whereas the control plot remains consistent, implying a less steep, stable line.

Question 19

What is one way to define a harsh environment?

Accepted Answer

A harsh environment is characterized by the dominance of extreme abiotic factors like extreme heat, cold, radiation, acidity, salinity, or aridity that can limit the growth and survival of organisms. While humans may be able to survive in some harsh environments with the use of technology and protective gear, the environment itself can still be considered harsh. The past or present presence of many organisms does not necessarily define a harsh environment as an ecosystem can support a high biodiversity despite the presence of some harsh abiotic factors.

Question 20

You have counted the number of amphibians and reptiles in the same experimental 1 km by 1 km area over the last five years.You also have a control plot of the same size nearby that is part of your sampling each year.Every year you have reviewed your data to understand which species were common or rare,and whether equal numbers of individuals were counted in those categories.What your data show is that in the experimental plot more species become rare to encounter and a large percentage of species that you do encounter tends to be more common from year one to year five.However,this is not the case in the control plot,which shows no change from year one to year five.You now plan to plot these data for a presentation.What will your diversity indices look like?

Accepted Answer

The data suggests that species diversity (H) is not affected by time in the control plot, indicating a more stable ecosystem. In contrast, in the experimental plot, species diversity is negatively associated with time, meaning there is a loss of diversity over time due to factors such as habitat fragmentation or disturbance. Plotted on a graph, the two lines will likely show no change in the control plot and a downward trend in the experimental plot.

Quiz 10: Patterns in Species Richness