Question 1

A commercial fisherman is very concerned that overfishing will result in a decrease in tuna population size, thus affecting his catches in future years. What strategy can he employ to make sure that the tuna population can be sustained in the long term?

Accepted Answer

Catching only old fish (past the reproductive age) allows younger, reproducing fish to remain in the population, ensuring that the tuna can continue to reproduce and sustain their population over time.

Question 2

In any one place, multiple species of the lizard genus Anolis can coexist because they hunt food in different ways and in different parts of the vegetation.

Accepted Answer

Different species of Anolis lizards have adapted to different niches within a habitat, allowing them to minimize competition and coexist in the same area. They may have different body sizes, morphologies, and behaviors that enable them to hunt different types of prey in different microhabitats within the same vegetation. For example, some species may be arboreal and hunt insects on leaves or branches, while others may be ground-dwelling and feed on small invertebrates on the forest floor. This is a classic example of resource partitioning, where species use different strategies to exploit available resources in a shared environment.

Question 3

Which of the following organisms would likely be a K-strategist?

Accepted Answer

K-strategists are organisms that have a long life span, reproduce slowly, and invest a lot of energy into the care of their offspring. Humans fit this description because we have a long life span, reproduce relatively slowly, and invest a lot of time and energy into raising our offspring. Pine trees, salmon, frogs, and grasshoppers are all examples of r-strategists, which are organisms that have a short life span, reproduce quickly, and invest very little energy into the care of their offspring.

Question 4

Which of the following organisms would likely be an r-strategist?

Accepted Answer

Pine trees are a classic example of r-strategists, as they produce many small, lightweight seeds that are dispersed widely and have a high reproductive potential. This strategy allows them to take advantage of unpredictable environmental conditions and rapid colonization of new habitats. In contrast, humans, whales, kangaroos, and owls are all examples of K-strategists, which invest more heavily in fewer offspring with a higher likelihood of survival in stable environments.

Question 5

Although all Anolis feed on insects and other invertebrates, they have evolved different feeding strategies that are reflected in:

Accepted Answer

All of the choices are correct. Anolis have evolved different feeding strategies that are reflected in their behavior, leg morphology, skull morphology, and habitat preference. These adaptations allow them to successfully capture and consume prey in their specific environment.

Question 6

You are studying the island biogeography of birds in the Caribbean islands and find a species-area relationship with a constant, c = 8.1, and an exponent, x = 0.15. Recall that the species-area relationship is defined as S = cA^x. How many bird species would you expect to find on an island of 120 mi²?

Accepted Answer

Using the species-area relationship formula, we can calculate the expected number of bird species on an island of 120 mi²: S = cA^x S = (8.1)(120)0.15 S = 16.67 Rounding down to the nearest whole number, we would expect to find 17 bird species on an island of 120 mi². Therefore, the best choice is B.

Question 7

Because most natural populations are actually metapopulations, we can only understand their dynamics if, in addition to the births and deaths of individuals, we also understand:

Accepted Answer

Understanding the extinction and colonization of local populations is necessary to understand the dynamics of metapopulations, as individuals may disperse between local populations. Additionally, understanding births and deaths alone is insufficient, as local populations may become extinct or be colonized by individuals from other populations. While r and K selection may be relevant to understanding population growth rates, it is not necessary to understand metapopulation dynamics.

Question 8

The life history of an organism takes into account:

Accepted Answer

The answer of The life history of an organism takes...

Question 9

The theory of island biogeography describes the number of species on an island as being determined by an equilibrium between the processes of immigration and extinction. Consider a small, far-offshore island and a large, near-shore island. Which island is expected to have a HIGHER equilibrium number of species?

Accepted Answer

Near-shore, large islands are expected to have a higher equilibrium number of species because they have a higher rate of immigration due to their larger size and closer proximity to mainland sources of species. Additionally, they have a lower rate of extinction due to a larger habitat area and greater ecological diversity.

Question 10

Habitat fragmentation occurs frequently with current logging practices. The figure below shows a fragmented set of patches in a logged area.  At equilibrium, which forest fragment is likely to hold the LARGEST number of species?

Accepted Answer

The answer of Habitat fragmentation occurs frequently with current logging...

Question 11

A researcher is studying a population with a unique age structure. Over the course of several decades, the histogram that depicts this structure first appears as a pyramid, becomes roughly rectangular in shape, and finally appears as an inverted pyramid (where the base is narrower than the top). How has this population changed over time?

Accepted Answer

The transition from a pyramid shape to a rectangular shape indicates a shift from rapid growth (many young people, fewer older people) to stability (similar numbers across age groups). The change to an inverted pyramid suggests a decline, as there are fewer young people and relatively more older people.

Question 12

Habitat fragmentation occurs frequently with current logging practices. The figure below shows a fragmented set of patches in a logged area.  Which of the subpopulations is MOST likely to go extinct?

Accepted Answer

Population K is the smallest patch and has the least connectivity with other patches, making it the most vulnerable to extinction due to habitat fragmentation.

Question 13

You are surveying biodiversity on a new island chain. You have counted the number of bird species on one island already. The next island is larger and closer to the mainland than the one you have just surveyed. According to the theory of island biogeography, the total number of its bird species should be _____ than on the current island because the rate of immigration to the new island should be _____ and the rate of extinction should be _____.

Accepted Answer

The theory of island biogeography suggests that larger islands closer to the mainland will have a greater number of species due to higher immigration rates and lower extinction rates.

Question 14

As a rough estimate, the species-area relationship derived from the theory of island biogeography predicts that a 90% reduction of habitat area results in a _____% loss of species diversity if no other factors are taken into account.

Accepted Answer

The species-area relationship, often modeled by the equation S = cAz (where S is the number of species, A is the area, c is a constant, and z is typically between 0.2 and 0.35), suggests that a 90% reduction in habitat area would lead to approximately a 50% loss in species diversity. This is because the relationship is not linear but follows a power law, where a smaller reduction in area leads to a disproportionately larger loss of species.

Question 15

You are studying the island biogeography of birds in the Caribbean islands and find a species-area relationship with a constant, c = 8.1, and an exponent, x = 0.15. Recall that the species-area relationship is defined as S = cA^x. How many bird species would you expect to find on an island of 240 mi²?

Accepted Answer

Using the species-area relationship formula, we can calculate the expected number of bird species on an island of 240 mi2 as:

S = 8.1(240)^0.15
S = 18.2

Therefore, we would expect to find approximately 18 bird species on an island of 240 mi2. The closest answer choice is B, which is 18 species.

Question 16

A population that is decreasing in size will have an age-structure histogram shaped like a(n):

Accepted Answer

As the population is decreasing in size, there would be a smaller number of young individuals in the population. This would result in an inverted pyramid shaped age-structure histogram, as there are more individuals in the older age groups and fewer in the younger age groups.

Question 17

You are working for a group that lobbies for conservation of chameleon (a type of lizard) diversity in tropical rain forests. You are asked to describe what type of land reserve you would like to have set aside for the long-term conservation of chameleons. For which of the following would you advocate?

Accepted Answer

The answer of You are working for a group that...

Question 18

Species diversity on habitat islands reflects the rate of:

Accepted Answer

Species diversity on habitat islands is influenced by the rate of new species arrival and the rate of colonist species extinction, as these factors determine the balance of species present on the island.

Question 19

A large forested area exists, but is then partially harvested for lumber. How does fragmentation affect the value of S (number of species at equilibrium) for forest-dependent species?

Accepted Answer

Fragmentation reduces the total area of forest available, which leads to a decrease in the value of S as there is less habitat for forest-dependent species to thrive.

Question 20

You are surveying biodiversity on a new island chain. You have counted the number of bat species on one island already. The next island is smaller and farther from the mainland than the one you have just surveyed. According to the theory of island biogeography, the total number of its bat species should be _____ than on the current island because the rate of immigration to the new island should be _____ and the rate of extinction should be _____. Refer to Figure 46.17. a.

b.

Accepted Answer

The answer of You are surveying biodiversity on a new...

Quiz 46: Population Ecology