Community Ecology

Question 1

An assemblage of plant and animal populations that live in a particular area or habitat.

Answer 1

Community

Question 2

characterizes communities. Populations of the various species in a community utilize, decompose, compete with, and alter the fates of each other. Together they form a system with its own emergent properties.

Answer 2

Interaction

Question 3

Seeks to explain the underlying mechanisms that create, maintain, and determine the fate of biological communities. Typically, patterns are documented by observation, and used to generate hypotheses about processes, which are not always easy to observe directly.

Answer 3

Community Ecology

Question 4

True/False

Community ecology hypotheses are always tested experimentally

Answer 4

False, they can involve special observations

Question 5

Examples include vegetation zonation, species lists, seasonal distribution of activity, and association of certain species

Answer 5

Patterns

Question 6

Examples include processes-herbivory, competition, predation risk, nutrient availability, patterns of disturbance, energy flow, history, and evolution

Answer 6

Processes

Question 7

is the way species are distributed relative to each other.
Some species provide a framework that creates habitats for other species. These species, in turn create habitats for others, etc.

Answer 7

Spatial Structure

Question 8

An example of this is trees in a rainforest stratifying into several different layers, each with a habitat of a distinct collection of species

Answer 8

Spatial Structure

Question 9

The time of the appearance and activity of species

Ex: arctic tundra, seasonal ponds, desert plants and animals that emerge after seasonal rains

Answer 9

Temporal Structure

Question 10

The number of species in a community. Clearly, the number of species we can observe is function of the area of the sample. It also is a function of who is looking. Thus, it is sensitive to sampling procedure

Answer 10

Species Richness

Question 11

The number of species in the community, and their relative abundances.
Species are not equally abundant, some species occur in large percentage of samples, others are poorly represented.

Answer 11

Diversity

Question 12

Some communities, such as tropical rainforests, are much more diverse than others, such as the great basin desert.

Answer 12

Yup

Question 13

Species Diversity is often expressed using Simpson’s diversity index:

Answer 13

D=1-S (pi)2

Question 14

the predictable change in species over time, as each new set of species modifies the environment to enable the establishment of other species, is virtually ubiquitous.

Answer 14

Ecological Succession

Question 15

A sphagnum bog community may persist for only a few decades before the process of ecological succession changes transform it into the surrounding Black Spruce Forest

Answer 15

Ecological Succession

Question 16

A forest fire may destroy a large area of trees, clearing the way for a meadow. Eventually, the trees take over and the meadow is replaced.

Lava flows in eventually weather, crack, and allow the establishment of vegetation. Over time this vegetation allows a soil to form, and ultimately, forest.

Answer 16

Ecological Succession

Question 17

creates opportunities for new species to invade an area and establish themselves.

Answer 17

Disturbance

Question 18

These species modify the environment, and create opportunities for other species to invade, The new species eventually displace the original ones

Answer 18

Invasion

Question 19

Eventually, the new species, in turn modify the environment enough to allow a new series of invaders, which ultimately replace them, etc

Answer 19

Succession

Question 20

events such as floods, fire, droughts, overgrazing, and human activity that damage communities, remove organisms from them, and alter resource availability.

Answer 20

Disturbance

Question 21

The best invaders have good dispersal powers and many offspring, but they are often not the best competitors in the long run

Answer 21

Word!

Question 22

Disturbance of a community is usually followed by recovery, called?
This sequence is driven by the interactions among dispersal, ecological tolerances, and competitive ability.

Answer 22

Ecological Succession

Question 23

The sequence of species on newly exposed landforms that have not previously been influenced by a community, e.g., areas exposed by glacial retreat.

Answer 23

Primary Succession

Question 24

occurs in cases which vegetation of an area has been partially or completely removed, but where soil, seeds, and spores remain

Answer 24

Secondary Succession

Question 25

Early in succession, species are generally excellent dispersers and good at tolerating harsh environments, but not the best interspecific competitors

Answer 25

Yeah

Question 26

As ecological succession progresses, they are replaced with species which are superior competitors, (but not as good at dispersing and more specialized to deal with the microenvironments created by other species likely to be present with them

Answer 26

Yup

Question 27

Early species modify their environment in such a way as to make it possible for the next round of species. These, in turn, make their own replacement by superior competitors possible.

Answer 27

Word

Question 28

is a more or less permanent and final stage of a particular succession, often characteristic of a restricted area.

Answer 28

Climax Community

Question 29

Climax communities are characterized by..

Answer 29

Slow rates of change (think redwood forests)

Question 30

They are dominated by species that are tolerant of....

Answer 30

Competition for resources

Question 31

Why are climax communities so rare?

Answer 31

Succession takes a long time, and the odds that disturbance will occur is high

Question 32

Do communities work like an integrated machine, in a predictable way (Clements)? Or, do they depend upon random events (Gleason)

Answer 32

Gleason was right, after disturbances communities often never reach former state

Question 33

A glacier retreated over 100km in Alaska, and three different successional patterns are occurring at once. This does not match other parts of Alaska. Who does this support?

Answer 33

Gleason

Question 34

True False: Disturbance and nonequilibrium are abnormal for most communties

Answer 34

False

Question 35

Communities usually are in a state of recovery from disturbance

Answer 35

True

Question 36

An area of habitat may form a patchwork of communities, each at different stages of ecological succession. Thus, disturbance and recovery potentially enable much greater biodiversity than is possible without disturbance

Answer 36

Ch'yeah!

Question 37

Do communities have a tightly prescribed organization and composition, or are they merely a loose assemblage of species?

Answer 37

Unclear, yet the 12 pond experiment supported that their composition is unstable and variable

Question 38

transfer of energy: i.e., eating, decomposing, obtaining energy via photosynthesis In other words, the hierarchy of feeding in a community

Answer 38

Trophic Interaction

Question 39

For every community, a diagram of trophic interactions is called -Energy flows from the bottom to the top

Answer 39

Food web

Question 40

One pattern through a food web

Answer 40

Food chain

Question 41

An organism’s habitat, the resources it uses, and its way of making a living, within the context of a community

Answer 41

Niche

Question 42

Very important in community ecology, yet it remains controversial because they are difficult or impossible to observe directly.

Answer 42

Niche

Question 43

This is reflected by an organisms place in a food web: ie., what it eats, what it competes with, what eats it. Each organism has the potential to create this for others

Answer 43

Niche

Question 44

modifies the environment in such a way that other organisms are able to live, in other cases, the keystone species is a predator that maintains diversity at a certain trophic level. Sometimes, they are mutualists, or “engineers

Answer 44

Keystone Species

Question 45

This keystone species preys upon sea urchins, allowing kelp forests to become established

Answer 45

California Sea Otters

Question 46

This keystone species prevents the establishment of dense mussel beds, allowing other species to colonize rocks on the Pacific Coast.

Answer 46

Pisaster Starfish

Question 47

This keystone species disperses in salt water. They take root and form a dense forest in saltwater shallows, allowing other species to thrive

Answer 47

Mangrove Trees

Question 48

At certain times of year, this keystone species is the sole source of food for honeyeaters, which in turn, are the pollinators for many other species of plants in Western Australia.

Answer 48

The Acorn Banksia

Question 49

Species at one trophic level influence species at other levels; the addition or subtraction of species affects the entire food web. Can be positive or negative for certain species

Answer 49

Trophic Cascade

Question 50

True/False: Most biological communities have both top down and bottom up effects on their structure and composition

Answer 50

True

Question 51

Fish affecting decreasing the amount of zooplankton (herbivores) and thereby increasing the amount of algae (producer) is an example of

Answer 51

Top down effect

Question 52

occurs when organisms in the same community seek the same limiting resource. This resource may be prey, water, light, nutrients, nest sites, etc.

Answer 52

Competition

Question 53

Competition among members of the same species

Answer 53

Intraspecific

Question 54

Competition among individuals of different species

Answer 54

Interspecific

Question 55

True/False: Individuals experience mostly intraspecific OR interspecific competition

Answer 55

False, they experience varying degrees of both

Question 56

occurs when individuals use the same limiting resource or resources, thus depleting the amount available to others.

Answer 56

Exploitation Competition

Question 57

occurs when individuals interfere with the foraging, survival, or reproduction of others, or directly prevent their physical establishment in a portion of a habitat.

Answer 57

Interference Competition

Question 58

The confused flour beetle, Triboleum confusum, and the red flour beetle, Triboleum castaneum cannibalize the eggs of their own species as well as the other, thus interfering with the survival of potential competitors. What is this an example of?

Answer 58

Interference competition

Question 59

In mixed species cultures, one species always excludes the other. Which species prevails depends upon environmental conditions, chance, and the relative numbers of each species at the start of the experiment.

Answer 59

Ya

Question 60

What has to happen for exclusion of a species to occur under exploitation competition

Answer 60

One organism must require less of the limiting resource to survive and reduce the quantity of the resource below some critical level

Question 61

For two species to coexist under exploitation competition they must...

Answer 61

Partition the resource

Question 62

When species coexist, what happens to their potential for growth?

Answer 62

It decreases.

Question 63

Interference competition usually results in what?

Answer 63

Exclusion of one competitor

Question 64

Model suggesting that two species cannot compete for the same limiting resource for long. Even a minute reproductive advantage leads to the replacement of one species by the other.

Answer 64

Competitive Exclusion Principal

Question 65

A famous experiment by the Russian ecologist, G.F. Gausse demonstrated that Paramecium aurellia outcompetes and displaces Paramecium caudatum in mixed laboratory cultures, apparently confirming the principle. (Interestingly, this is not always the case. Later studies suggest that the particular strains involved affect the outcome of this interaction

Answer 65

Competitive Exclusion Principle

Question 66

Which species generally decreases in mixed populations of P. aurelia and P. Caudatum

Answer 66

P. Caudatum

Question 67

Species that share the same habitat and have similar needs frequently use resources in somewhat different ways - so that they do not come into direct competition for at least part of the limiting resource. This is called

Answer 67

Resource Partitioning

Question 68

obviates competitive exclusion, allowing the coexistence of several species using the same limiting resource.

Answer 68

Resource Partitioning

Question 69

could be an evolutionary response to interspecific competition, or it could simply be that competitive exclusion eliminates all situations where resource partitioning does not occur.

Answer 69

Resource Partitioning

Question 70

As many as five different species of anoles may exist in the same forest, but each stays restricted to a particular space: some occupy tree canopies, some occupy trunks, some forage close to the ground. This is an example of:

Answer 70

Resource Partitioning

Question 71

Sympatric populations of similar species frequently have differences in body structure relative to allopatric populations of the same species.

Answer 71

Character Displacement

Question 72

This is thought to be an evolutionary response to interspecific competition.

Answer 72

Character Displacement

Question 73

When the two species occur together, G. fuliginosa has a much narrower beak that G fortis. Sympatric populations of G fuliginosa eats smaller seeds than G fortis: they partition the resource. Thought to be evolved in response to interspecific competition. This is an example of:

Answer 73

Character Displacement (on separate islands, both have intermediate beaks)

Question 74

the set of resources and habitats an organism could theoretically use under ideal conditions.

Answer 74

Fundamental Niche

Question 75

the set of resources and habitats an organism actually used: it is generally much more restricted due to interspecific competition (or predation.)

Answer 75

Realized Niche

Question 76

Gausse's rule states that....

Answer 76

Two organisms cannot occupy exactly the same niche.

Question 77

To explain Gauss's law it is thought that the more complex environments found in nature may enable more

Answer 77

Resource Partitioning

Question 78

when one species suffers and the other interacting species experiences no effect.

Answer 78

Amensalism

Question 79

Redwood trees falling into the ocean become floating battering-rams during storms, killing large numbers of mussels and other inter-tidal organisms is an example of

Answer 79

Amensalism

Question 80

involves the production and release of chemical substances by one species that inhibit the growth of another

Answer 80

Allelopathy

Question 81

chemicals produced by plants that seen to have no direct use in umetabolism, such as allelopathies

Answer 81

Secondary Substances

Question 82

Allelopathy can be seen as amensalism and one sided...

Answer 82

Interference competition

Question 83

Black Walnut (Juglans nigra) trees excrete an antibiotic called juglone. Juglone is known to inhibit the growth of trees, shrubs, grasses, and herbs found growing near black walnut trees.

Answer 83

Allelopathy

Question 84

Certain species of shrubs, notably Salvia leucophylla (mint) and Artemisia californica (sagebrush) are known to produce allelopathic substances that accumulate in the soil during the dry season. These substances inhibit the germination and growth of grasses and herbs in an area up to 1 to 2 meters from the secreting plants.

Answer 84

Allelopathy

Question 85

an interspecific interaction where one species benefits and the other is unaffected. Ubiquitous in nature.

Answer 85

Commensalism

Question 86

Birds nesting in trees is an example of...

Answer 86

Commensalism

Question 87

These kind of organisms frequently live in nests or bodies of other species

Answer 87

Commensal Organisms

Question 88

Ant colonies harbor rove beetles as commensals. These beetles mimic the ants behavior, and pass as ants. They eat detritus and dead ants. Anemonefish live within the tentacles of anemones. They have specialized mucus membranes that render them immune to the anemone’s stings. They gain protection by living in this way.

Answer 88

Commensalism

Question 89

An interspecific interaction between two species that benefits both members.

Answer 89

Mutualism

Question 90

Populations of each species grow, survive and/or reproduce at a higher rate in the presence of the other species. Widespread in nature, and occur among many different types of organisms.

Answer 90

Mutualism

Question 91

Mychorrhizae increase the capability of plant roots to absorb nutrients. In return, the host provides support and a supply of carbohydrates.

Answer 91

Mutualism

Question 92

Many corals have endosymbiotic organisms called zooxanthellae (usually a dinoflagellate). These provide the corals with carbohydrates via photosynthesis. In return, they receive a relatively protected habitat from the body of the coral.

Answer 92

Mutualism

Question 93

a type of mutualism in which individuals interact physically, or even live within the body of the other mutualist. Frequently, the relationship is essential for the survival of at least one member.

Answer 93

Mutualistic Symbiosis

Question 94

Lichens are a fungal-algal symbiosis (that frequently includes a third member, a cyanobacterium.) The mass of fungal hyphae provides a protected habitat for the algae, and takes up water and nutrients for the algae. In return, the algae (and cynaobacteria) provide carbohydrates as a source of energy for the fungus.

Answer 94

Mutualistic Symbiosis

Question 95

Mutualisms that are not essential for the survival of either species. Individuals of each species engage in mutualism when the other species is present.

Answer 95

Facultative Mutualisms

Question 96

essential for the survival of one or both species.

Answer 96

Obligate Mutualisms

Question 97

These 4 organisms obtain food at the expense of their hosts or prey.

Answer 97

predators, parasites, parasitoids, and herbivores

Question 98

tend to be larger than their prey, and consume many prey during their lifetimes

Answer 98

Predator

Question 99

These are smaller than their host.

Answer 99

Parasites and pathogens

Question 100

These may have one or many hosts during their lifetime, and consume the host from either the outside or inside

Answer 100

Parasites

Question 101

These are parasitic microbes-many generations may live within the same host

Answer 101

Pathogens

Question 102

A parasite that consumes its host from the inside

Answer 102

Endoparasite

Question 103

A parasite that consumes its from the outside

Answer 103

Ectoparasite

Question 104

These hunt their prey like predators, but lay their eggs within the body of a host, where they develop

Answer 104

Parasitoids

Question 105

Animals that eat plants. This interaction may resemble predation, or parasitism.

Answer 105

Herbivores

Question 106

The relationships between predator and prey, and parasites and hosts, have coevolved over long periods of time.

Answer 106

Predator-Prey and Parasite-Host Coevolution

Question 107

First a parasite (or predator) evolves a trait that allows it to attack its host (or prey). Next, natural selection favors host individuals that are able to defend themselves against the new trait. As the frequency of resistant host individuals increases, there is natural selection for parasites with novel traits to subvert the host defenses. This process continues as long as both species survive.

Answer 107

Evolutionary Arms Race

Question 108

The common milkweed, Asclepias syriaca has leaves that contain cardiac glycosides: they are very poisonous to most herbivores. This renders them virtually immune to herbivory by most species

Answer 108

Parasite host Coevolution

Question 109

Monarch butterfly larvae have evolved the ability to tolerate these toxins, and sequester them within their bodies. They are important specialist hervivores of milkweeds.

Answer 109

Parasite host coevolution

Question 110

These sequestered compounds serve the additional purpose of making monarch larvae virtually inedible to vertebrate predators.

Answer 110

Cool!

Question 111

Predation is what kind of mortality factor to the host population?

Answer 111

Density Dependent

Question 112

Prey rmay epresent what to the predators?

Answer 112

Limiting Resource

Question 113

The density of the prey population, in turn, affects the birth and death rates of the predator population. i.e, when prey become particularly common, predators increase in numbers until prey die back due to increased predation, this, in turn, inhibits the growth of prey.

Answer 113

Predation-Prey Population Dynamics

Question 114

Occurs between predators and prey and is necessary for the stability of both populations. Feedback mechanisms may control the densities of both species

Answer 114

Dynamic Balance

Question 115

A method of control of the prickly pear cactus was initiated with the introduction of Cactoblastis cactorum, a cactus eating moth from Argentina, in 1925. By 1930, densities of the prickly pear cactus were significantly reduced.

Answer 115

Regulation by a host population (predator prey dynamics)

Question 116

In other cases, there are alternate prey to support the predator and the prey is permanently excluded

Answer 116

Ya, like the freshwater fish , which exclude other fish to other prey like insect larvae

Question 117

Most predators do not respond instantaneously to the availability of prey and adjust their reproduction accordingly. If predator populations grow faster than prey populations, they may overshoot the number of prey that are able to support them

Answer 117

Lag Time

Question 118

This leads to a rapid decline in the prey, followed by a rapid decline in the predator. Once the predator becomes rare, the prey population may begin growing again.

Answer 118

Predator-Prey Oscillation