Question 1

In pollination, which characteristic of the plant being pollinated is necessary to attract all pollinators?

Accepted Answer

The presence of food or other reward, such as nectar, is a necessary characteristic to attract a wide range of pollinators, as it provides an incentive for them to visit the flower.

Question 2

Termites live on cellulose from dead wood.They depend on protists in their guts to provide enzymes that can digest wood.Protists would die outside the termites, and the termites would starve without the protists to aid in digestion.This is an example of

Accepted Answer

This is an obligate mutualism because without the protists, the termites would not be able to survive and would starve. The protists also benefit from this relationship by relying on the termites for a stable environment and a constant supply of cellulose to digest.

Question 3

In a mutualistic interaction between a sessile species and a motile species, the sessile partner often receives benefits that are only available because of the motile species.In a pollination interaction, the plant would be least likely to receive which benefit as a result of the interaction?

Accepted Answer

In a pollination interaction, the plant is unlikely to receive acquisition of nutrients as a benefit because this is not a function of pollination. The other options, reproduction, increased sexual diversity, possible dispersion to new habitats, and possible increased efficiency of seed production are all benefits that can be gained by the plant through pollination.

Question 4

Hummingbirds transport pollen from flower to flower, providing an essential pollination service, while benefiting energetically from the flower nectar.Along with pollen, hummingbirds also transport mites.These tiny invertebrates crawl onto a hummingbird's beak to hitch a ride from one flower to the next.The tiny mites exert no significant impact on the hummingbirds.The hummingbird-flower interaction is _______; the hummingbird-mite interaction is _______.

Accepted Answer

The hummingbird-flower interaction is a mutualism, as both parties benefit from the interaction. Hummingbirds obtain nectar for energy while transporting pollen, which allows the plant to reproduce. The hummingbird-mite interaction is commensalism, as the mites benefit from hitching a ride on the hummingbird without harming or benefiting the hummingbird.

Question 5

Several lizards of the genus Anolis live on Caribbean islands.They all feed on insects, but they feed in different areas of the habitat.For example, some live in leaf litter, others in tree branches, and still others on tree trunks or in surrounding shrubs.This variation in habitat and feeding locations enables various species of Anolis to share a habitat because of

Accepted Answer

This variation in habitat and feeding locations is an example of resource partitioning, which allows different species to coexist in the same habitat by utilizing different resources.

Question 6

A lichen is a fungus and an alga living together.The alga provides food for the fungus through photosynthesis.The fungus acts like a sponge, providing water for both organisms.Both species get their limiting resources from each other and cannot survive without each other.This is an example of

Accepted Answer

This is an example of obligate mutualism because both species are dependent on each other for survival and cannot survive without each other.

Question 7

The habitat and food requirements of grizzly bears and black bears are similar but not identical.A study in British Columbia examined predicted versus actual distributions of these two species using hair traps and DNA analysis of the hair to determine whether black bears or grizzly bears were using particular areas.Most of the area was suitable for both species, but black bears mainly occurred in valley bottoms and open habitats, whereas grizzly bears occurred in more closed habitats (forest) at higher elevations.The lack of overlap in habitat suggests that the two bear species are practicing

Accepted Answer

The lack of overlap in habitat between grizzly bears and black bears suggests that the two species are practicing resource partitioning, where they divide the resources available to reduce competition and coexist in the same ecosystem. This is different from competitive exclusion, where one species completely outcompetes and eliminates another, or interference competition, where one species actively prevents another from accessing a resource. Exploitation competition and character displacement are also mechanisms of reducing competition, but they do not specifically refer to the division of resources among different species in a shared habitat.

Question 8

Which situation in a community is least likely to lead to asymmetrical competition?

Accepted Answer

When two plants have similar growth rates and nutrient needs, it is less likely for one to outcompete the other as they are evenly matched. Therefore, this situation is least likely to lead to asymmetrical competition. In contrast, options A, B, and E are more likely to lead to asymmetrical competition because one species is likely to be better adapted to the resource and outcompete the others. Option C is also a form of asymmetrical competition as certain plants may be better at extracting nutrients from poor soil than others.

Question 9

Most trees are dispersed by means of frugivores.If frugivore populations in an area declined because of disease, what would most likely happen to the tree species previously dispersed in this way?

Accepted Answer

With a decline in frugivore populations, the primary agents for seed dispersal are significantly reduced. This means that seeds are less likely to be spread over a wide area, leading to the trees remaining concentrated near their parent plants. Other options like finding other means of dispersal or ceasing fruit and seed production are less immediate or direct consequences of reduced frugivore populations.

Question 10

Photosynthetic single-celled dinoflagellates, called zooxanthellae, live within coral polyps.Zooxanthellae use CO₂ and nitrogenous wastes from the polyps to form oxygen and sugars, which in turn are used by both polyps and zooxanthellae for metabolism.As water temperatures warm, polyps eject their zooxanthellae, causing the coral to turn a bleached white.Corals slowly starve without zooxanthellae.As climate change causes warmer waters, we may expect to see a(n) _______ in corals as the number of zooxanthellae _______.

Accepted Answer

As water temperatures warm, the zooxanthellae become stressed and begin to produce toxic compounds that are harmful to the coral polyps. In response, the polyps eject their zooxanthellae, leading to a decrease in the number of zooxanthellae and ultimately causing coral bleaching. As a result, we may expect to see a decrease in corals as the number of zooxanthellae decreases. Therefore, the correct choice is C.

Question 11

Hummingbirds are important pollinators.They are attracted to the color red.Red flowers have evolved in many different plants that are not closely related, all of which are pollinated by hummingbirds.What does this example of coevolution suggest about the importance of color in pollination?

Accepted Answer

Color is important for attracting pollinators like hummingbirds, but it is not essential for pollination to occur, as other factors can also attract pollinators.

Question 12

African wild dogs avoid competition with lions by living in areas lions are unlikely to inhabit.A species might also be a fugitive species if it

Accepted Answer

A fugitive species is one that avoids competition by living in areas or utilizing resources that are avoided by dominant or competitive species. Being competitively subordinate to another species (option E) allows for the coexistence of both species without direct competition. Options A, B, C, and D do not necessarily make a species a fugitive species.

Question 13

Character displacement, such as the evolution of different-sized beaks in Galápagos finches, relates most closely to which aspect of competition?

Accepted Answer

Character displacement refers to the evolution of differences in characteristics or traits in species that occupy the same ecological niche. Resource partitioning is the process where species divide or partition resources in order to reduce competition, and is a common mechanism of character displacement. Therefore, option C, Resource partitioning, is the most relevant aspect of competition related to character displacement.

Question 14

A forest is destroyed by fire, and then plant species begin to recolonize the burned site.Which types of species are likely to compete best in this environment?

Accepted Answer

Dormant species whose germination is enhanced by fire are likely to compete best in a recently burned environment. These species are adapted to the effects of fire and can quickly germinate and grow in the newly opened space without competition from established vegetation. This allows them to take advantage of the available resources and establish a foothold in the site before other species arrive. Over time, the mixture of species that colonize the area may eventually lead to the original species composition, but initially, the dormant species that are adapted to fire will have the competitive advantage.

Question 15

In coral reefs, the cells of the cylindrical coral polyp contain single-celled photosynthetic algae, or zooxanthellae.Coral polyps filter organic material from water and metabolize it, forming carbon dioxide and nitrogenous wastes that zooxanthellae use in photosynthesis.The oxygen and sugars they form in turn are used by coral polyps and dinoflagellates for metabolism.Many corals cannot feed successfully when they lose their zooxanthellae, but zooxanthellae can usually grow and reproduce outside of the corals.For zooxanthellae, this interaction is _______; for corals, it is _______.

Accepted Answer

The interaction between zooxanthellae and corals is a form of mutualism because both parties benefit: zooxanthellae receive carbon dioxide and nitrogenous wastes from corals for photosynthesis, while corals get oxygen and sugars in return. However, it is facultative for zooxanthellae, meaning they can survive and reproduce outside of the corals, but it is obligate for many corals, as they cannot feed successfully without their zooxanthellae.

Question 16

The Rhode Island salt marsh experiments on the rush Juncus gerardii and the shrub Iva frutescens showed that Iva dominates and Juncus has a low biomass in the high intertidal zone.However, in the low intertidal, where salinity and waterlogging are greater, Iva depends on Juncus for survival.Which general statement best describes the cause of the change in this relationship?

Accepted Answer

Environmental variations, such as changes in salinity and waterlogging in the low intertidal zone, can shift the relationship between species from competition to mutualism or commensalism, as seen with Iva and Juncus.

Question 17

Anemonefishes can tolerate the stings of anemone tentacles, whereas most fish species cannot.An anemonefish lives among an anemone's tentacles, where the anemone protects it from its predators, butterfly fishes.This is an example of

Accepted Answer

The answer of Anemonefishes can tolerate the stings of anemone...

Question 18

Scarlet gilia, a common Rocky Mountain wildflower, produces red flowers early in the season and transitions to producing white flowers late in the season.Pollination by hummingbirds is replaced by pollination by moths.This adaptation would most likely benefit the pollination interaction because it would

Accepted Answer

By transitioning to producing white flowers and being pollinated by moths later in the season, the scarlet gilia can extend its pollination season and increase the likelihood of successful pollination. This adaptation may also allow for a wider range of pollinators to visit the plant, reducing competition and ensuring that the plant continues to receive pollination services throughout the growing season.

Question 19

In which type of environment is a positive interaction, such as a mutualism or commensalism, least likely to be found?

Accepted Answer

The answer of In which type of environment is a...

Question 20

The actions of a frugivore become part of a mutualistic interaction only when the frugivore

Accepted Answer

The answer of The actions of a frugivore become part...

Quiz 55: Species Interactions