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BIOL 3012 > 54 Chapter > Flashcards

54 Chapter Flashcards

1
Q

Biological community

A

A group of populations of different species living close enough to interact.

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2
Q

Interspecific interaction

A

A relationship between individuals of two or more species in a community.

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3
Q

Interspecific interactions include:

A

Competition, predation, herbivory, symbiosis, and facilitation.

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4
Q

We’ll use the symbols + and - to indicate how each Interspecific interaction affects the survival and reproduction of the two species engaged in the interaction. A 0 indicates that the population is not affected by the interaction in any known way.

A
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5
Q

Interspecific competition

A

A -/- interaction that occurs when individuals of different species compete for a resource that limits their growth and survival.

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6
Q

Competitive exclusion

A

The concept that when two similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population.

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7
Q

Ecological niche

A

The sum of a species’ use of the biotic and abiotic resources in its environment.

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8
Q

We can use the niche concept to restate the principle of competitive exclusion: Two species cannot coexist permanently in a community if their niches are identical.

A

Trus

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9
Q

Resource partitioning

A

The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species.

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10
Q

Fundamental niche

A

The niche potentially occupied by a species

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11
Q

Realized niche

A

The portion of a species’ fundamental niche that it actually occupies.

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12
Q

Ecologists can identify the fundamental niche of a species by…

A

Testing the range of conditions in which it grows and reproduces in the absence of competitors

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13
Q

Allopatric definition

A

Geographically separate

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14
Q

Sympatric definition

A

Geographically overlapping

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15
Q

Character displacement

A

The tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species.

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16
Q

Predation

A

Refers to a +/- interaction between species in which one species, the predator, kills and eats the other, the prey.

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17
Q

Aposematic coloration

A

The bright warning coloration of many animals with effective physical or chemical defenses.

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18
Q

Cryptic coloration

A

Camouflage that makes a potential prey difficult to spot against its background.

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19
Q

Batesian mimicry

A

A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators.

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20
Q

Müllerian mimicry

A

Reciprocal mimicry by two unpalatable species.

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21
Q

Many predators also use mimicry.

A

True

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22
Q

Herbivory

A

Refers to a +/- interaction in which an organism eats part of a plant or alga.

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23
Q

Symbiosis

A

An ecological relationship between organisms of two different species that live together in direct and intimate contact.

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24
Q

Parasitism

A

A +/- symbiotic interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process.

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25
Q

Endoparasites

A

Parasites that live within the body of their host

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26
Q

Ectoparasites

A

Parasites that feed on the external surface of a host.

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27
Q

Some ecologists have estimated that at least one-third of all species on Earth are parasites.

A

True

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28
Q

Mutualism

A

Is a symbiotic relationship or an Interspecific interaction that benefits both species (+/+)

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29
Q

Obligate mutualism

A

A type of mutualism in which at least one species has lost the ability to survive on its own.

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30
Q

Facultative mutualism

A

A type of mutualism in which both species can survive alone.

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31
Q

Commensalism

A

An interaction between species that benefits one of the species but neither helps nor harms the other (+/0)

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32
Q

Some commensal associations involve one species obtaining food that is inadvertently exposed by another.

A

True

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33
Q

Facilitation

A

An interaction in which one species has a positive effect on the survival and reproduction of another species without the intimate association of a symbiosis.

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34
Q

Species diversity

A

The number and relative abundance of species in a biological community.

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35
Q

Species diversity has two components:

A

Species richness
Relative abundance

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36
Q

Species richness

A

The number of species in a biological community.

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37
Q

Relative abundance

A

The proportional abundance of different species in a community.

38
Q

Shannon diversity

A

An index of community diversity symbolized by H and represented by the equation
H=-(p(subA) ln p(subA) + p(subB) ln p(subB)…) where A,B,C… are species, p is the relative abundance of each species, and ln is the natural logarithm.

39
Q

A higher value of H indicates…

A

A more diverse community

40
Q

More and more, researchers are using DNA sequencing for species identification as it becomes cheaper and as DNA sequences from more organisms are placed in comparative databases.

A

True

41
Q

The small size of microorganisms makes them particularly difficult to sample, so ecologists now use molecular tools to help determine microbial diversity.

A

True

42
Q

Despite the challenges, measuring species diversity is essential for…

A

Understanding community structure and for conserving diversity

43
Q

Biomass

A

The total mass of all organisms in a habitat

44
Q

Higher-diversity communities not only produce more biomass, but are often more resistant to ____________.

A

Invasive species

45
Q

Invasive species

A

A species, often introduced by humans, that takes hold outside its native range.

46
Q

The researchers concluded that relatively diverse communities captured more of the resources available in the system, leaving fewer resources for the invader and decreasing its survival.

A

True

47
Q

Trophic structure

A

The different feeding relationships in an ecosystem, which determine the route of energy flow and the pattern of chemical cycling.

48
Q

Food chain

A

The pathway along which food energy is transferred from trophic level to trophic level, beginning with producers.

49
Q

Food web

A

The interconnected feeding relationships in an ecosystem.

50
Q

Energetic hypothesis

A

The concept that the length of a food chain is limited by the inefficiency of energy transfer along the chain

51
Q

The energetic hypothesis predicts that food chains should be relatively longer in habitats of higher photosynthetic productions, since the amount of energy stored in primary producers is greater than in habitats with lower photosynthetic production.

A

True

52
Q

Dominant species

A

A species with substantially higher abundance or biomass than other species in a community. Dominant species exert a powerful control over the occurrence and distribution of other species.

53
Q

One way to discover the impact of a dominant species is…

A

to remove it from the community

54
Q

Keystone species

A

A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche.

55
Q

Ecosystem engineers (foundation species)

A

An organism that influences community structure by causing physical changes in the environment.

56
Q

V —> H means that an increase in vegetation (V) will increase the numbers or biomass of herbivores, but not vice-versa. In this situation, herbivores are limited by vegetation, but vegetation is not limited by herbivory. In contrast, V<—H means that an increase in herbivore biomass will decrease the abundance of vegetation, but not vice versa. A double headed arrow indicates that each trophic level is sensitive to changes in the biomass of the other.

A

True

57
Q

Two common models of community organization:

A

The bottom-up model and the top-down model

58
Q

Bottom-up model

A

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.
-Postulates a unidirectional influence from lower to higher trophic levels. For example, V—>H

59
Q

Top-down model

A

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.
N<—V<—H<—P

60
Q

Biomanipulation

A

An approach that applies the top-down model of community organization to alter ecosystem characteristics. For example, ecologists can prevent algal blooms and eutrophication by altering the density of higher-level consumers in lakes instead of by using chemical treatments.

61
Q

Disturbance

A

A natural or human-caused event that changes a biological community and usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal role in structuring many communities.

62
Q

Nonequilibrium model

A

A model that maintains that communities change constantly after being buffeted by disturbances.

63
Q

A high level of disturbance is generally the result of frequent and intense disturbance, while low disturbance can result from either a low frequency or low intensity of disturbance.

A

True

64
Q

Intermediate disturbance hypothesis

A

The concept that moderate levels of disturbance can foster greater species diversity than low or high levels of disturbance.

65
Q

Small-scale disturbances are useful for…

A

Creating patches of different habitats across a landscape, which help maintain diversity in a community.

66
Q

Ecological succession

A

Describes the transition in the species composition of a community following a disturbance; establishment of a community in an area virtually barren of life.
-The disturbed area may be colonized by a variety of species, which are gradually replaced by other species, which are in turn replaced by still other species.

67
Q

Primary succession

A

A type of ecological succession that occurs in an area where there were originally no organisms present and where soil has not yet formed.
-Is ecological succession where there are no organisms and no soil.

68
Q

Early-arriving species and later-arriving species may be linked by one of three key processes

A

-Early-arrivals may facilitate the appearance of the later species by making the environment more favorable.
-Early arrivals may inhibit establishment of the later species, so that successful colonization by later species occurs in spite of, rather than because of, the activities of the early species.
-Early-arrivals may be completely independent of the later species, which tolerate conditions created in succession but are neither helped nor hindered by early species.

69
Q

Secondary succession

A

A type of succession that occurs where an existing community has been cleared by some disturbance that leaves the soil or substrate intact.

70
Q

Ecological succession is a response to disturbance of the environment, and the strongest disturbances today are human activities.

A

True

71
Q

Ecologists have recognized that large-scale biogeographic factors contribute to the tremendous range of diversity observed in biological communities. The contributions of two biogeographic factors in particular:

A

The latitude of a community and the area it occupies.

72
Q

In the 1850s, both Charles Darwin and Alfred Wallace pointed out that plant and animal life was generally more abundant and diverse in the ________ than in other parts of the globe.

A

Tropics

73
Q

The two key factors in latitudinal gradients of species richness are probably…

A

Evolutionary history and climate

74
Q

The growing season in tropical rain forests is about five times as long as in the tundra communities of high latitudes. In effect, biological time runs about five times as fast in the tropics as near the poles, so intervals between speciation events are shorter in the tropics.

A

True

75
Q

In terrestrial communities, the two main climatic factors correlated with diversity are:

A

Sunlight and precipitation

76
Q

Evapotranspiration

A

The evaporation of water from soil and plants

77
Q

Evapotranspiration is a function of…

A

Solar radiation, temperature, and water availability

78
Q

Potential Evapotranspiration

A

A measure of potential water loss that assumes that water is readily available

79
Q

Species-area curve

A

The biodiversity pattern that shows that the larger the geographic area of a community is, the more species it has.

80
Q

The first, and still widely-used, mathematical description of the species-area relationship was proposed a century ago:

A

S = cA^z
Where S is the number of species found in a habitat, c is a constant, and A is the area of the habitat. The exponent z tells you how many more species should be found in a habitat as its area increases.

81
Q

Island

A

Any patch surrounded by an environment not suitable for the “island” species.

82
Q

Two factors that determine the number of species on the island:

A

The rate at which new species immigrate to the island and the rate at which species become extinct on the island.

83
Q

Two physical features of the island affect immigration and extinction rates:

A

Its size and its distance from the mainland.

84
Q

Small islands generally have lower _____________ because potential colonizers are less likely to reach a small island than a large one.

A

Immigration rates

85
Q

Small islands have a higher ___________ because they generally contain fewer resources, have less diverse habitats, and have smaller population sizes.

A

Extinction rate

86
Q

Why is the Island Equilibrium Model so named?

A

Because an equilibrium will eventually be reached where the rate of species immigration equals the rate of species extinction in an island.

87
Q

A pathogen can be particularly virulent in a new habitat because new host populations have not had a chance to become resistant to the pathogen through natural selection.

A

…

88
Q

Human activities are transporting pathogens around the world at unprecedented rates.

A

True

89
Q

Zoonotic pathogen

A

A disease-causing agent that is transmitted to humans from other animals. Either through contact with an infected animal or by means of an intermediate species, called a vector.

90
Q

Vector

A

An organism that transmits pathogens from one host to another.

BIOL 3012 (14 decks)

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