Question 1

You are doing biology field work studying two species of lizards on a small volcanic island. Although quite hostile to each other when they accidentally meet, the two species usually remain in separate parts of the island. Species A seems to live and hunt insects only in the lower grassland part of the island. Species B seems to live and hunt only in the upper rocky areas. Species A has a short tongue but has longer legs and is a faster runner. Species B is short, squat, runs slower, but has a long tongue. You observe Species A chasing down some pretty large, fast-moving insects, while Species B meanders from rock to rock, using its long tongue to get insects hiding between rocks and in cracks. What principle of ecology do your two lizard species demonstrate?

Accepted Answer

The two lizard species demonstrate resource partitioning, as they have partitioned the resources available on the island based on their physical characteristics and hunting strategies. Species A hunts in the lower grasslands and chases down insects with its longer legs and faster running speed, while Species B hunts in the upper rocky areas and uses its long tongue to get insects hiding between rocks and in cracks. This allows both species to coexist on the island without directly competing with each other for resources.

Question 2

Barnacles are filter-feeding molluscs that live by filtering plankton from seawater. This is a description of the barnacles':

Accepted Answer

The description of barnacles as filter-feeding molluscs that live by filtering plankton from seawater defines their niche, which refers to their role and position in the environment, including their interactions with other species and their use of resources. This is different from a habitat, which refers to the physical location where an organism lives, or an ecosystem, which encompasses all the living and nonliving components of an area. While barnacles may exist within a community of other organisms, this is not the defining characteristic of their species.

Question 3

In a typical ecosystem, a species whose removal would have a bigger impact than any other would be a/an:

Accepted Answer

A keystone species plays a critical role that is disproportional to its abundance or biomass. Its removal could cause significant shifts in the structure and function of the ecosystem, making it more vulnerable to other pressures or disturbances. In contrast, community or dominant species may be important but are not necessarily irreplaceable or essential for the ecosystem's integrity. Ecological dominants may be the most abundant or powerful but may not have a unique or central niche that affects other species' interactions or benefits.

Question 4

An accidental spill of a pesticide locally wiped out the most abundant species of butterfly in coastal California. Most of the bird species in the area had fed on this butterfly, but they switched prey to moths, and thus the birds showed only a small decrease in population size. The butterflies were a/an:

Accepted Answer

The fact that the butterflies were the most abundant species of butterfly in the area suggests they were an ecological dominant, but the fact that most bird species in the area fed on them suggests they were not a keystone species as the bird species were able to switch to another food source without major consequences. The description does not provide evidence to suggest the species was endangered or a pioneer species.

Question 5

The "address" where a species lives within a certain area is identified as its:

Accepted Answer

Habitat refers to the specific area where a particular species lives within an ecosystem. Ecosystem is a larger system that includes all living organisms in an area and their physical environment. Community refers to all the living organisms in a particular ecosystem, while population refers to a group of individuals of the same species living in the same area.

Question 6

Keystone species are:

Accepted Answer

Keystone species can be of any number and anywhere on the food chain. They play a crucial role in maintaining the balance of an ecosystem by exerting a disproportionate influence on their environment relative to their abundance. Examples of keystone species include sea otters, beavers, and sharks.

Question 7

If we find an orange plant that lacks chlorophyll living on a green plant, it is likely that the orange plant is a:

Accepted Answer

An orange plant that lacks chlorophyll and lives on a green plant is likely a parasite. This is because it is gaining nutrients from the green plant without providing any benefit in return.

Question 8

A botanist has found that the giant saguaro, Carnegiea gigantea, lives in the Sonoran Desert below the freeze line and in some very dry regions (such as Yuma) to the eastern edge of Arizona. She has described the ________ of saguaro.

Accepted Answer

The botanist has described the geographic range or specific location where the giant saguaro is found. This refers to its habitat, which is the natural environment or type of ecosystem in which a particular species is typically found. Options A, B, and C refer more specifically to the resources needed by a species, rather than the general location where it is found.

Question 9

If two species of woodpeckers eat two different kinds of beetle larvae on pine trees in a forest, we would identify that as:

Accepted Answer

Resource partitioning refers to the differentiation of niches that enables similar species to coexist in a community. In this case, the woodpeckers are able to coexist in the forest by consuming different types of beetle larvae on pine trees, which is an example of resource partitioning. Mutualism involves both species benefiting from the interaction, and commensalism involves one species benefiting while the other is unaffected. Competitive exclusion refers to one species outcompeting another for resources, leading to the exclusion of the other species.

Question 10

The coral organisms on a coral reef cannot be replaced by any other organism. For that reason, we identify those species as:

Accepted Answer

Keystone species are those that have a disproportionately large impact on their environment relative to their abundance. In the case of coral reefs, the coral organisms are considered keystone species because they provide the physical structure and habitat that supports the entire ecosystem of the reef. Without the coral, many other species would not be able to survive, making the coral organisms essential to the functioning of the ecosystem.

Question 11

Barnacles live on exposed rocks washed over by waves at the shore. This is a description of the barnacles':

Accepted Answer

The description provided is of the barnacles' habitat, which refers to the specific physical environment in which they live.

Question 12

In interspecific competition, the competitors are generally competing for:

Accepted Answer

In interspecific competition, individuals of different species are competing for limited resources such as food, water, and shelter. The competition is often intense as each species tries to outcompete the other in order to survive and reproduce. While factors such as social status and mate choice may play a role in some interspecific interactions, competition for resources is the primary driver of competition between species.

Question 13

A red-shouldered hawk chases a falcon away from a dead squirrel. This is an example of:

Accepted Answer

The interaction between the red-shouldered hawk and the falcon is an example of interspecific competition, as they are both vying for the same food resource, the dead squirrel.

Question 14

Choose the characteristic associated with a top predator who is also a keystone species.

Accepted Answer

A keystone species is a species whose presence in a community has a greater impact on the community than its abundance would suggest. If a top predator is also a keystone species, its loss could result in significant alterations to the diversity within the community, making choice D the best option. While a top predator may also be the largest or fastest animal in the community, these characteristics are not necessarily associated with being a keystone species. Similarly, while a top predator may have the ability to cause extinction within the community, this is not a characteristic specific to being a keystone species.

Question 15

The population of a carnivore has doubled this year. Predict what will likely happen to the population of its prey over the next 12 months.

Accepted Answer

If the population of a carnivore doubled, it means there are more predators hunting for prey. Therefore, it is likely that the population of its prey will decrease as they are being hunted and consumed by the increased number of carnivores. This is a common pattern in predator-prey relationships, where changes in one population affect the other population in the opposite direction.

Question 16

A small number of species that are abundant in a given community are called:

Accepted Answer

The answer of A small number of species that are...

Question 17

The "occupation" of a species in an area is identified as its:

Accepted Answer

The "occupation" of a species in an area refers to its niche, which includes its role in the ecosystem, its interactions with other species, and its use of resources. The habitat refers to the physical location where the species lives, the community is the group of different species living in an area, and the population is the group of individuals of the same species living in the same area. Therefore, the correct answer is C, niche.

Question 18

On a hike along the desert slope of the Sierra Nevada Mountains in California, you notice that there is an abundance of pinyon pine and juniper trees. We would identify these two plants as:

Accepted Answer

Pinyon pine and juniper trees are ecological dominants because they are the most abundant and influential species in that particular ecosystem. They outcompete other plant species for resources and play a major role in shaping the ecosystem's structure and function.

Question 19

Biodiversity includes the:

Accepted Answer

Biodiversity refers to the variety of species in a given ecosystem, so the only option that reflects this definition is choice C. Genetic diversity is a component of biodiversity, but it is not limited to keystone species alone. The distribution of species in only one population does not account for the diversity of other populations or species present in the ecosystem. The number of individuals in a population is not a measure of biodiversity, but rather population size.

Question 20

When placed in the same habitat, Paramecium aurelia will replace Paramecium caudatum. This is an example of:

Accepted Answer

This is an example of competitive exclusion, where two species competing for the same resources cannot coexist in the same habitat. In this case, Paramecium aurelia outcompetes and replaces Paramecium caudatum in the shared habitat.

Quiz 35: An Interactive Living World 2: Communities in Ecology