BSC 116: EXAM 4 (HEINRICH) CHAPTER 54

According to bottom-up and top-down control models of community organization, which of the following expressions would imply that an increase in the size of a carnivore (C) population would negatively impact on its prey (P) population, but not vice versa? A) P ← C B) P → C C) C ↔ P D) P ← C → P E) C ← P → C

A

According to the equilibrium model of island biogeography, species richness would be greatest on an island that is A) large and close to a mainland. B) large and remote. C) small and remote.

A

Biomanipulation can best be described as A) removing many of the next higher trophic level organisms so that the struggling trophic level below can recover. B) a means of reversing the effects of pollution by applying antidote chemicals that have a neutralizing effect on the community. C) an example of how one would use the bottom-up model for community restoration.

A

Elephants are not the most dominant species in African grasslands, yet they influence community structure. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following describes why elephants are the keystone species in this scenario? A) Essentially all of the other species depend on the presence of the elephants to maintain the community. B) Grazing animals depend upon the elephants to convert forests to grassland. C) Elephants prevent drought in African grasslands.

A

Imagine five forest communities, each with 100 individuals distributed among four different tree species (W, X, Y, and Z). Which forest community would be most diverse? A) 25W, 25X, 25Y, 25Z B) 40W, 30X, 20Y, 10Z C) 50W, 25X, 15Y, 10Z

A

Which of the following is an example of Müllerian mimicry? A) two species of unpalatable butterfly that have the same color pattern B) a day-flying hawkmoth that looks like a wasp C) a chameleon that changes its color to look like a dead leaf D) two species of rattlesnakes that both rattle their tails E) two species of moths with wing spots that look like owl's eyes

A

Which of the following is an example of aposematic coloration? A) stripes of a skunk B) eye color in humans C) green color of a plant D) colors of an insect-pollinated flower E) a katydid whose wings look like a dead leaf

A

Which term do ecologists use to describe the ability of a community either to resist change or to recover to its original state after change? A) stability B) succession C) partitioning

A

Why do moderate levels of disturbance result in an increase in community diversity? A) Habitats are opened up for less competitive species. B) Competitively dominant species infrequently exclude less competitive species after a moderate disturbance. C) The environmental conditions become optimal.

A

______________ living apart, caused by geographic isolation (like mountains and water, and the speed of emergence of new species is low (like Darwin's finches, natural selection occurs)

Allopatry

_____________ when one organism causes harm to another organism, but the other is not affected. (-/0) (cattle trampling on grass)

Amensalism

According to the competitive exclusion principle, two species cannot continue to occupy the same A) habitat. B) niche. C) territory. D) range. E) biome.

B

In a tide pool, 15 species of invertebrates were reduced to eight after one species was removed. The species removed was likely a(n) A) pathogen. B) keystone species. C) herbivore. D) resource partitioner. E) mutualistic organism.

B

Keystone predators can maintain species diversity in a community if they A) competitively exclude other predators. B) prey on the community's dominant species. C) allow immigration of other predators. D) reduce the number of disruptions in the community. E) prey only on the least abundant species in the community.

B

Resource partitioning would be most likely to occur between A) sympatric populations of a predator and its prey. B) sympatric populations of species with similar ecological niches. C) sympatric populations of a flowering plant and its specialized insect pollinator.

B

Species richness increases A) as we increase in altitude in equatorial mountains. B) as we travel southward from the North Pole. C) on islands as distance from the mainland increases.

B

The energetic hypothesis and dynamic stability hypothesis are ideas that attempt to explain A) plant defenses against herbivores. B) the length of food chains. C) the evolution of mutualism. D) resource partitioning. E) competitive exclusion.

B

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is that A) tropical communities are younger. B) tropical regions generally have more available water and higher levels of solar radiation. C) higher temperatures cause more rapid speciation.

B

Which of the following best describes resource partitioning? A) competitive exclusion that results in the success of the superior species B) slight variations in niche that allow similar species to coexist C) two species that can coevolve to share identical niches D) differential resource utilization that results in a decrease in community species diversity E) a climax community that is reached when no new niches are available

B

Which of the following is the most accepted hypothesis as to why invasive species take over communities into which they have been introduced? A) Invasive species are more aggressive than native species in competing for the limited resources of the environment. B) Invasive species are not held in check by the predators and agents of disease that have always been in place for the native species. C) Humans carefully select which species will outcompete nuisance native species.

B

White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, whereas the white-breasted nuthatch searches from the top of the trunk down. These hunting behaviors best illustrate which of the following ecological concepts? A) competitive exclusion B) resource partitioning C) character displacement D) keystone species E) bottom-up and top-down hypotheses

B (prevents competition)

Monarch butterflies are protected from birds and other predators because of cardiac glycosides they incorporate into their tissues from eating milkweed when they were in their caterpillar stage. The wings of a different species of butterfly, the Viceroy, look nearly identical to the Monarch so predators that have learned not to eat the bad-tasting Monarch avoid Viceroys as well. This example best describes

Batesian mimicry

________________ intentionally altering the food web

Biomanipulation

Unidirectional influence from lower to higher trophic levels. (V --> H)

Bottom up model

________________ the lower trophic level affects the community structure of the higher trophic levels by means of resource restriction. (increases vegetation, increase herbivores, and increases carnivores)

Bottom up model

A model of community organization in which mineral nutrients influence community organization by controlling plant or phytoplankton numbers, which in turn control herbivore numbers, which in turn control predator numbers.

Bottom-up model

____________________ focuses on the lower trophic levels and the factors that drive interactions at the base of the food chain. This could be thought of as a resource driven (resources being food or habitat availability) system. An example of bottom-up control would be nutrient driven changes to seagrass ecosystems. In the northern Gulf of Mexico increases in nutrient levels to seagrass meadows from land runoff can cause increased growth of the epiphytes that grow on seagrass blades. This increased abundance of epiphytes changes the population sizes of herbivores that graze on this algae (mesograzers) and this increase results in increases in their predators.

Bottom-up model

Based on the intermediate disturbance hypothesis, a community's species diversity is increased by A) frequent massive disturbance. B) stable conditions with no disturbance. C) moderate levels of disturbance.

C

Food chains are sometimes short because A) only a single species of herbivore feeds on each plant species. B) local extinction of a species causes extinction of the other species in its food chain. C) most of the energy in a trophic level is lost as it passes to the next higher level.

C

Which of the following is an example of Batesian mimicry? A) an insect that resembles a twig B) a butterfly that resembles a leaf C) a nonvenomous snake that looks like a venomous snake D) a fawn with fur coloring that camouflages it in the forest environment E) a snapping turtle that uses its tongue to mimic a worm, thus attracting fis

C

Which statement best describes the evolutionary significance of mutualism? A) Mutualism offers more biodiversity to a community. B) Individuals partaking in a mutualistic relationship are more resistant to parasites. C) Interaction increases the survival and reproductive rates of mutualistic species.

C

Why are food chains relatively short? A) Top-level feeders tend to be more numerous than lower-trophic-level species. B) Top-level feeders tend to be small but are capable of conserving more energy. C) Longer chains are less stable and energy transfer between levels is inefficient.

C

_______________ one species benefits, but the other is not affected at all. (+/0) (pilot fish and shark)

Commensalism

_____________ a group of populations, and makes up an interacting group of various species in a common location. An example would be a forest with animals, trees, plants, earthworms, bacteria, and fungi.

Community

___________ when species compete for resources needed for growth, survival, and reproduction. they are both striving for the same (-/-)

Competition

Predatory evolutions by prey and predators: Cryptic coloration Aposematic coloration Batesian mimicry Mullerian mimicry

Cryptic coloration: camouflage Aposematic coloration: Animal is trying to send a warning because it is poisonous, very brightly colored and trying to stick out like a frog or snake Batesian mimicry: when one animal is NOT poisonous and is harmless, but it is trying to look like one that is, it is a bluff Mullerian mimicry: when two organisms resemble each other, and they are both poisonous and trying to mimic appearances to show danger (MEAN-MULTIPLE)

The principle of competitive exclusion states that A) two species cannot coexist in the same habitat. B) competition between two species always causes extinction or emigration of one species. C) competition in a population promotes survival of the best-adapted individuals. D) two species that have exactly the same niche cannot coexist in a community.

D

Which of the following could qualify as a top-down control on a grassland community? A) limitation of plant biomass by rainfall amount B) influence of temperature on competition among plants C) influence of soil nutrients on the abundance of grasses versus wildflowers D) effect of grazing intensity by bison on plant species diversity

D

Which of the following is a correct statement about the McArthur/Wilson Island Equilibrium Model? A) The more species that inhabit an island, the lower the extinction rate. B) As the number of species on an island increases, the emigration rate decreases. C) Competitive exclusion is less likely on an island that has large numbers of species. D) Small islands receive few new immigrant species.

D

Which of the following statements is consistent with the principle of competitive exclusion? A) Bird species generally do not compete for nesting sites. B) The random distribution of one competing species will have a positive impact on the population growth of the other competing species. C) Two species with the same fundamental niche will exclude other competing species. D) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of the two competing species. E) Natural selection tends to increase competition between related species.

D

Which of the following terms is used by ecologists to describe the community interaction where one organism makes the environment more suitable for another organism? A) parasitism B) mutualism C) inhibition D) facilitation E) commensalism

D

Why do tropical communities tend to have greater species diversity than temperate or polar communities? A) They are less likely to be affected by human disturbance. B) There are fewer parasites to negatively affect the health of tropical communities. C) Tropical communities are low in altitude, whereas temperate and polar communities are high in altitude. D) Tropical communities are generally older than temperate and polar communities.

D

_______________ a key component to community function and diversity.

Disturbance

___________ the species that is the most abundant and has the most biomass. it exerts a powerful control over the occurrence and distribution of other species. (can cause an increase or decrease in biodiversity)

Dominant species

According to the nonequilibrium model, A) communities will remain in a climax state if there are no human disturbances. B) community structure remains stable in the absence of interspecific competition. C) communities are assemblages of closely linked species that are irreparably changed by disturbance. D) interspecific interactions induce changes in community composition over time. E) communities are constantly changing after being influenced by disturbances.

E

As you study two closely related predatory insect species, the two-spot and the three-spot avenger beetles, you notice that each species seeks prey at dawn in areas without the other species. However, where their ranges overlap, the two-spot avenger beetle hunts at night and the three-spot hunts in the morning. When you bring them into the laboratory and isolate the two different species, you discover that the offspring of both species are found to be nocturnal. You have discovered an example of A) mutualism. B) character displacement. C) Batesian mimicry. D) facultative commensalism. E) resource partitioning

E

How might an ecologist test whether a species is occupying its realized or its fundamental niche? A) Study the temperature range and humidity requirements of the species. B) Observe if the niche size changes after the addition of nutritional resources to the habitat. C) Observe if the niche size changes after the introduction of a similar non-native species. D) Measure the change in reproductive success when the species is subjected to environmental stress. E) Remove a competitor species to see if the species expands its range.

E

Prairie dogs once covered the expanses of the Great Plains. Their grazing made the grass more nutritious for the huge herds of bison, and they were preyed upon by a variety of snakes, raptors, and mammals. In fact, the black-footed ferret (now endangered) specialized in prairie dog predation. Today, increases in housing and agricultural developments have eradicated many prairie dog towns. Which of the following statements about prairie dogs is true? A) Their realized niche has expanded. B) They have a competitive relationship with bison. C) They are probably a poor candidate for keystone species. D) Their fundamental niche has been compromised. E) Their fundamental niche has expanded.

E

Which of the following is an example of cryptic coloration? A) bands on a coral snake B) brown or gray color of tree bark C) markings of a viceroy butterfly's wings D) colors of an insect-pollinated flower's petals E) a "walking stick" insect that resembles a twig

E

A type of niche that an organism given there is no limiting factors in the environment or resources the organism can use. (pre-competitive niche), theoretical

Fundamental niche

______________ type of theoretical niche that is large in size, elaborates on the various roles of a particular species could do, and there is no competition for resources or predators

Fundamental niche

________________ when a herbivore eats a plant, the herbivore benefits and the plant does not, but sometimes it can be mutualistic. (+/-) (grasshopper and plant)

Herbivory

_______________ means that some disturbance increases species diversity. Allows for a mix and creates patches of different habitats. (Low disturbance=dominant species exclude others) (High disturbance=high stress, slow growing, slow colonizing species) (Too much=kills off habitats)

Intermediate disturbance species

______________ the species that are the key niches in maintaining community structure, they promote biodiversity so something else will not take over, and they have a great effect on all of the other species due to its ecological role/niche, like a facilitator, the ecosystem engineers

Keystone species

After secondary succession, the disturbance, _____ and ____ show up first. (when there is soil)

Lichens and mosses

An island that is larger and closer:

More immigration, less extinction, less emigration, more diversity

Evidence shows that some grasses benefit from being grazed. Which of the following terms would best describe this plant-herbivore interaction?

Mutualism

_____________ when both species benefit from the interaction (crocodile and bird) (+/+)

Mutualism

____________ sum of biotic and abiotic factors and the role and place in the habitat for an organism

Niche

Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain nutrients and water from the vascular tissues of the trees. The trees derive no known benefits from the dwarf mistletoes. Which of the following best describes the interactions between dwarf mistletoes and trees?

Parasitism

_________________ great for the parasite, but can be bad for the host, whether it is direct or indirect (mosquito and human)(+/-)

Parasitism

___________________ good for the predator, but bad for the prey. one is benefitting, and one is trying to escape or is getting killed (+/-). (lion and the zebra)

Predation

________________ succession that begins with building back the soil, (the disturbance took it away) like after a volcanic eruption or glacier, and prokaryotes and fungi build it back up

Primary succession

A type of niche that is occupied by a viable population of a species in the presence of a competitor species. Each species is better adapted to a portion of the resources. (post-competitive)

Realized niche

_______________ type of niche that is where the species lives, it is smaller than the other, and elaborates on what the species actually does

Realized niche

____________ proportion of the individuals that belongs to each species, how common or rare a species is in a defined location or community

Relative abundance

_________ succession with soil, like after fire burns the forest (it takes less time and it does not need to weather rocks, or create soil)

Secondary succession

_____________ chains are more stable. (food webs and trophic structures)

Short

___________ and ________________ determines the number of species in the island equilibrium model.

Size and distance

__________________ the number of different species (simply a count, not how many)

Species richness

How is diversity measured?

Species richness and relative abundance (Shannon Diversity Index)

_____________ living together, spectates occurs even though the two groups are found in the same area, evolution from a single species in the same habitat

Sympatry

Influence moves from top trophic levels to bottom. (V <-- H)

Top down model

_____________ the higher trophic structure influences the community structure of a lower trophic level through predation (removing the consumers means the herbivores raise, which then lowers vegetation)

Top down model

A model of community organization in which predation influences community organization by controlling herbivore numbers, which in turn control plant or phytoplankton numbers, which in turn control nutrient levels; also called the trophic cascade model.

Top-down model

_______________ this model focuses on how top consumers influence lower trophic levels. This could be thought of as a predator driven system. One of the classic examples of a top-down trophic cascade is the sea otter story from the Pacific coast. Key players in the food chain are sea otters, sea urchins and kelp. Decreases in the sea otter population, whether due to human hunting (historically) or climate change (recently), led to increases in the urchin population. As urchins graze on kelp, more sea urchins resulted in less kelp cover. These changes can have indirect effects too. In the sea otter example, loss of kelp forests affected the fish populations that used the kelp as a habitat.

Top-down model

wide niche overlap leads to

competitive exclusion -weaker competitor eliminated from local area

Species richness can be maintained by _____________

disturbance

_______________ +/- relationship that includes predatory, herbivory, and parasitism

exploitation

An island that is smaller and farther away:

less immigration, more extinction, more emigration, less diversity

The order of the food web or trophic structure:

primary producer primary consumer --- quaternary consumer

Narrow niche is when a organism is very __________ to fill a very specific role within an ecosystem

specialized

______________ a relationship between two organisms that is long, lasting, close, and tight (one must benefit)

symbiosis

____________ a powerful interaction that can control an entire ecosystem. It occurs when the trophic level in a food web is suppressed. A series of changes in the population sizes of organisms at different trophic levels in a food chain, occurring when predators at high trophic levels indirectly promote populations of organisms at low trophic levels by keeping species at intermediate trophic levels in check. may become apparent when a top predator is eliminated from a system.

trophic cascade

_____________ the feeding relationships among species, and the energy moves up from the lower levels to the higher

trophic structure