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Biology II > ch. 53 > Flashcards

ch. 53 Flashcards

1
Q

what does population ecology explore

A

abundance, dispersion, and age structure of populations

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2
Q

population

A

group of individuals of a single species living in the same general area

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3
Q

what are populations described by

A

their boundaries and size

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4
Q

population size

A

number of individuals

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5
Q

density

A

number of individuals per unit area or volume

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6
Q

dispersion

A

pattern of spacing among individuals within the boundaries of the population

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7
Q

how are population sizes estimated?

A
  • extrapolation from small samples
  • index of population size (number of nests)
  • mark-recapture method
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8
Q

what are sampling techniques used for

A

estimating densities and total population sizes

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9
Q

mark-recapture method

A
  • scientists capture, tag, and release a random sample of ind. in pop
  • marked ind. given time to mix back into pop
  • scientists capture a second sample of ind. and note how many are marked
  • N = sn/x
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10
Q

immigration

A

influx of new ind. from other areas

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11
Q

emigration

A

movement of ind. out of a population

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12
Q

what increases the size of a population

A

births and immigration

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13
Q

what decreases the size of a population

A

deaths and emigration

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14
Q

what influencers the spacing of ind. in a population

A

environmental and social factors

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15
Q

most common pattern of dispersion

A

clumped

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16
Q

clumped dispersion

A

ind. aggregate in patches
- influenced by resource availability
- mating behavior and group defense against predators

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17
Q

patterns of dispersion

A
  • clumped
  • uniform
  • random
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18
Q

uniform dispersion

A

ind. evenly distributed
- influenced by social interactions (territoriality)

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19
Q

territoriality

A

defense of a bounded space against other ind.

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20
Q

random dispersion

A

position of each. ind. is independent of others
- occurs in absence of strong interactions or repulsions among individuals

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21
Q

demography

A

study of vital statistics of a population and how they change over time

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22
Q

life table

A

age-specific summary of the survival and reproductive rates within a population

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23
Q

how are life tables often made

A

by following the fate of a cohort

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24
Q

cohort

A

group of ind. of same age

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25
Q

why are males often ignored when studying sexually reproducing species

A

only females produce offspring

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26
Q

survivorship curve

A

graphic way of representing the data in a life table

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27
Q

types of survivorship curves

A

type 1, type 2, type 3

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28
Q

type 1 survivorship curve

A

low death rates during early/middle life, increase in death rates among older age groups

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29
Q

type 2 survivorship curve

A

constant death rate over organism’s life span

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30
Q

type 3 survivorship curve

A

high death rates for the young and a lower death ate for survivors

31
Q

where do ecologists often study population growth

A

ideal, unlimited conditions

32
Q

what do idealized situations help us understand

A

capacity of species to increase and the conditions that may facilitate this growth

33
Q

if immigration/emigration are ignored, the change in population equals what?

A

births - deaths

34
Q

how can populations growth be expressed mathematically

A

delta N / delta t = B - D

35
Q

delta N

A

change in population size

36
Q

delta t

A

time interval

37
Q

B - D =

A

R - difference between number of births/deaths in time interval

38
Q

exponential population growth

A

population increase under idealized conditions

39
Q

shape of exponential population growth

A

J-shaped curve

40
Q

carrying capacity (K)

A

maximum population size the environment can support
- varies with abundance of limiting resources

41
Q

logistic population growth model

A

per capita rate of population growth approaches 0 as the population size nears carrying capacity

42
Q

curve of laboratory populations of paramecium

A

fits S-shaped curve
- organisms grown in constant environment lacking predators and competitors

43
Q

what is the logistic model useful for

A
  • thinking about how populations grow
  • predict rates of population recovery
  • estimate sustainable harvest rates
  • estimate size which populations may become extinct
44
Q

3 key components of an organism’s life history

A
  1. age at first reproduction (maturity)
  2. how often organism reproduces
  3. how many offspring are produced per reproductive episode (clutch size)
45
Q

semelparity

A

big-bang reproduction, reproduce once and die

46
Q

iteroparity

A

repeated reproduction, produce offspring repeatedly

47
Q

what can having finite resources lead to?

A

trade-offs

48
Q

ex. of trade-offs

A
  • large number of small seeds to ensure some grow/reproduce
  • moderate number of large seeds that provide large store of energy to help seedlings establish
49
Q

r - unstable environment, density independent ex.

A
  • small size of organism
  • energy used to make each ind. is low
  • many offspring produced
  • early maturity
  • short life expectancy
  • each ind. reproduces only once
  • type III survivorship
50
Q

K - stable environment, density dependent ex.

A
  • large size of organism
  • energy used to make each ind. is high
  • few offspring produced
  • late maturity
  • long life expectancy
  • ind. can reproduce more than once
  • type I or II survivorship
51
Q

2 important questions about regulation of population growth

A
  1. what environmental factors stop a population from growing indefinitely?
  2. why are some populations fairly stable in size, while others not?
52
Q

density-independent populations

A

birth and death rate don’t change with population density

53
Q

density-dependent population

A

birth rates fall and death increase with rising population density

54
Q

what are density-dependent birth and death rates an example of

A

negative feedback ack that regulates population growth

55
Q

what are density-dependent birth and death rates affected by

A
  • competition for resources
  • disease
  • predation
  • territoriality
  • toxic wastes
  • intrinsic factors
56
Q

in crowded populations, what does increasing population density intensify

A

competition for resources, results in a lower birth rate

57
Q

pathogen spread in dense populations

A

pathogens spread more rapidly

58
Q

what happens to predator prey interactions with a dense population

A

as prey population builds up, predators, may feed preferentially on that species

59
Q

territoriality and population density

A

individuals compete for limited space

60
Q

what are intrinsic factors that regulate population size

A

physical factors

61
Q

what can accumulation of toxic wastes contribute to

A

density-dependent regulation of population size

62
Q

what do lynx populations follow

A

10-year boom and bust cycle of hare populations

63
Q

hypothesis of hare’s population following cycle of winter food supply

A
  • if correct: cycles should stop if food supply increased
  • additional food provided experimentally, whole pop increased in size but continued to cycle
64
Q

hypothesis of hare’s population cycle driven by pressure from other predators

A
  • 95% of hares killed by predators
  • data supports hypothesis
65
Q

what can increase when a population becomes crowded and resource competition increases?

A

emigration often increases

66
Q

metapopulations

A

groups of populations linked by immigration and emigration

67
Q

what do local populations in a metapopulation occupy

A

suitable habitat surrounded by unsuitable habitat

68
Q

growth of human population

A

increased relatively slowly until 1650, then began to grow exponentially, but began to slow during 1960s

69
Q

current global human population

A

more than 7.2 billion people

70
Q

age structure

A

relative number of individuals of each age in a population
- affects population growth

71
Q

age-structure diagrams (pyramids)

A

help predict population’s growth trends and illuminate social conditions to help us plan for the future

72
Q

what global population of humans do ecologists predict for 2050

A

8.1-10.6 billion

73
Q

what is the carrying capacity of earth

A

it is uncertain
- but there are estimates on logistic growth models, area of habitable land, and food availability

74
Q

what can our carrying capacity be limited by

A
  • food
  • sapce
  • nonrenewable resources
  • buildup of wastes

Biology II (43 decks)

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