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General Ecology > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

the distribution of populations is limited to

A

ecologically suitable habitats

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2
Q

what are population distributions characterized by

A
  1. range
  2. dispersion
  3. density
  4. abundance
  5. dispersal
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3
Q

range

A

geographic distribution of the species

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4
Q

dispersion

A

spatial arrangement of individuals and habitats

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5
Q

density

A

number of individuals per unit of space

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6
Q

abundance

A

size of the population

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7
Q

dispersal

A

patterns of movement of individuals within and among populations

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8
Q

spatial structure

A

the pattern of density and spacing of individuals in a population

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9
Q

Fundamental niche

A

the range of abiotic conditions (e.g., temperature, humidity, salinity) under which a species can persist

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10
Q

what may prevent a population from persisting in an area

A

Competitors, predators, and pathogens

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11
Q

realized niche

A

the range of abiotic and biotic conditions under which a species can persist

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12
Q

geographic range

A

a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple)

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13
Q

what do small-scale variation in the environment create

A

geographic ranges that are composed of small patches of suitable habitat

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14
Q

Ecological niche modeling

A

the process of determining the suitable habitat conditions for a species

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15
Q

Ecological envelope

A

the range of ecological conditions that are predicted to be suitable for a species (differs from the realized niche, which describes conditions in which a species currently exists).

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16
Q

when is predicting the potential geographic range of a species difficult

A

when only a few individuals exist

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17
Q

what can ecological niche modeling predict

A

the expansion of pest species

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18
Q

Geographic Distribution (Range):

A

all the areas that a species occupies during

their life time. This might include rivers/ocean

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19
Q

Endemic

A

species that live in a single, often isolated, location

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20
Q

Cosmopolitan

A

species with very large geographic ranges that can span several continents. Cosmopolitan species: rock doves, house sparrows, peregrine falcons, killer whales, cattle egrets

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21
Q

Abundance

A

the total number of individuals in a population that exist within a defined area (e.g., total number of lizards on a mountain).

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22
Q

what does the total abundance of a population provide

A

a measure of whether a population is thriving or on the brink of extinction

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23
Q

in a population, the number of individuals per unit area or volume; calculated by dividing abundance by area

A

density

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24
Q

what happens if population density is greater than what the habitat can support

A

some individuals must leave or the population will experience lower growth and survival

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25
Q

where does the largest density of individuals typically occur

A

near the center of a population’s geographic range

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26
Q

what happens near the edges of the range

A

conditions become less ideal and population densities decrease

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27
Q

the spacing of individuals with respect to one another within the geographic range of a population

A

dispersion

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28
Q

when individuals are aggregated in discrete groups (e.g., social groups or clustering around resources).

A

clustered (clumped) dispersion

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29
Q

when each individual maintains a uniform distance between itself and its neighbors (e.g., defended territories, croplands).

A

evenly spaced dispersion

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30
Q

when the position of each individual is independent of other individuals; not common due to non-random environmental heterogeneity

A

random dispersion

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31
Q

social antagonism

A

results in a spaced distribution

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32
Q

mutual attraction

A

leads to clumping

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33
Q

what happens in the absence of social antagonism or mutual attraction

A

individuals may distribute themselves randomly

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34
Q

individuals distribute themselves randomly

A

individuals are not influenced by the positions of others

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35
Q

since a random dispersion pattern implies that spacing is not related to a biological process

A

it is often used as the model against which an observed dispersion may be compared

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36
Q

probability theory

A

provides us with the tools to make such comparisons

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37
Q

poisson distribution

A

a probability distribution of discrete random variables (variables that can take on only a finite number of values)

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38
Q

expresses the probability of a number of events occuring in a fixed period of time and/or space if these events occur with a known average rate, and are independent of the time since the last event

A

poisson distribution

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39
Q

poisson distribution formula

A

P(x) = M^xe^-M/x!

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40
Q

M

A

the mean number of individuals per space

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41
Q

x!

A

the factorial of x

42
Q

e

A

2.7183

43
Q

when might an ecologist use the Poisson distribution

A

to make a quantitative determination of the pattern of dispersion

44
Q

how does an ecologist use the poisson distribution to make a quantitative determination of the pattern of dispersion

A

by comparing the mean (M) of our distribution with the variance (V)

45
Q

the variance of a random variable

A

a measure of the spread about the mean of the distribution of that variable

46
Q

dispersal

A

the movement of individuals from one area to another (away from their birth place or away from centers of high population)

47
Q

migration

A

the seasonal movement of individuals back and forth between habitats

48
Q

what is the mechanism by which individuals can move between suitable habitats

A

dispersal

49
Q

allows species to colonize areas outside of their geographic ranges

A

dispersal

50
Q

a way to avoid areas of high competition or high predation risk

A

dispersal

51
Q

when are barriers to dispersal revealed

A

when species are introduced to new areas/regions

52
Q

census

A

counting every individual in a population

53
Q

what do scientists conduct when a census is not feasible

A

survey

54
Q

survey

A

count a subset of the population

55
Q

area and volume based surveys

A

define the boundaries of an area or volume and then count all of the individuals in the space

56
Q

what is the size of the defined space related to

A

the abundance and density of the population

57
Q

what is possible by taking multiple samples

A

it is possible to determine how many individuals are in an average sample

58
Q

line-transect surveys

A

surveys that count the number of individuals observed as one moves along a line

59
Q

what can line-transect survey data be converted into

A

area estimates of a population (detection probabilities)

60
Q

mark-recapture survey

A

a method of population estimation in which researchers capture and mark a subset of a population from an area, return it to the area, and capture a second sample of the population after time has passed

61
Q

the population size is estimated by assuming that:

A

initially captured individiuals/population size = marked recaptured individuals/total individuals captured in 2nd sample

62
Q

how can we estimate population densities

A

mark and recapture

63
Q

mark and recapture studies

A

some individuals from a population are initially captured, marked, and released back into the population

64
Q

M/N=

A

R/C

65
Q

M

A

number initially captured and marked

66
Q

N

A

number in population

67
Q

C

A

total number captured on 2nd attempt

68
Q

R

A

number of recaptures on 2nd attempt

69
Q

N=

A

MC/R

70
Q

how can dispersal be quantified

A

measuring how far individuals travel from a single source location, marked and recaptured, radio transmitters

71
Q

lifetime disperal distance

A

the average distance an individual moves from where it was born to where it reproduces

72
Q

what does lifetime disperal distance provide an estimate for

A

how fast a population can increase its geographic range

73
Q

dispersal can cause a geographic range to expand rapidly if

A

a few individuals can disperse much farther than the average individual

74
Q

Populations with high abundance also have large

A

geographic ranges

75
Q

what may cause the relationship between population abundance and range

A

resource availability; species are likely to cover the area that contains the resources that they require

76
Q

what may cause the large amount of variation in the abundance-range size regression

A

fluctuations within a geographic range

77
Q

what does the regression caused by fluctuations suggest

A

reducing the range of a population will reduce the size of that population

78
Q

how is the density of a population correlated to the body size of the species

A

negatively

79
Q

what can we expect from the relationship between population density and body size

A

a given plot of habitat to support fewer large individuals than it does small individuals

80
Q

what is essential to colonizing new areas

A

dispersal

81
Q

dispersal limitation

A

the absence of a population from suitable habitat because of barriers to dispersal

82
Q

barriers

A

large expanses of inhipitable habitat that an organism can’t cross

83
Q

human barriers for dispersal

A

roads, forest clearings

84
Q

habitat corridor

A

a strip of favorable habitat located between two large patches of habitat that facilitates dispersal (narrow band of trees that connects forests)

85
Q

what habitats do individuals choose

A

those that provide the most energy

86
Q

what happens as individuals move to a high-quality habitat

A

resources must be divided among more individuals (reduced per capita benefit)

87
Q

per capita benefit can fall so low that

A

an individual would benefit by moving to the low-quality habitat

88
Q

ideal free distribution

A

when individuals distribute themselves among different habitats in a way that allows them to have the same per capita benefit; assumes perfect knowledge of habitat variation

89
Q

why do individuals in nature rarely meet the expectations required by the ideal free distribution

A
  • they may not be aware that other habitats exist
  • fitness is not solely determined by maximizing resources
    • presence of predators or territory owners
90
Q

what can the ideal free distribution allow

A

populations in low-quality habitats to persist over time

91
Q

subpopulations

A

when a large population is broken up into smaller groups that live in isolated patches

92
Q

when individuals frequently disperse among subpopulations

A

the whole population functions as a single structure; all subpopulations increase and decrease in abundance synchronously

93
Q

when disperal is infrequent

A

each subpopulation fluctuates independently

94
Q

basic metapopulation model

A

decribes a scenario in which there are patches of suitable habitat embedded within a matrix of unsitable habitat; all suitable patches are assumed to be of equal quality

95
Q

source-sink metapopulation model

A

builds upon the basic metapopulation model and accounts for the fact that not all patches of suitable habitat are of equal quality

96
Q

source subpopulation

A

in high-quality habitats, subpopulaitons that serve as a source of dispersers within a metapopulation

97
Q

sink subpopulations

A

in low-quality habitats, subpopulations that rely on outside dispersers to maintain the subpopulation within a metapopulation

98
Q

landscape metapopulation model

A

considers both differences in the quality of the suitable patches and the quality of the surrounding matrix

99
Q

represents the most realistic and most complex spatial structure of populations

A

landscape metapopulation model

100
Q

habitat patchiness has led to 3 models of population

A
  1. metapopulation model
  2. source-sink model
  3. landscape model

General Ecology (16 decks)

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