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Ecology > Populations > Flashcards

Populations Flashcards

1
Q

Define population

A

a group of individuals of the same species that live in the same place at the same time

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2
Q

Define metapopulations

A

Local subpopulations. Populations that are divided in to subpopulations due to environmental variability. They occupy suitable habitat that is separated from other subpopulations by areas that are unsuitable.

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3
Q

Define population density

A

the number of individuals of a species found in a unit area

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4
Q

What does population density help to control?

A

birthrate, mortality, growth rate

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5
Q

What are 4 ways to measure population density?

A

total counts, mark-recapture, quadrant sampling, indices of abundance

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6
Q

Define carrying capacity

A

the number of individuals that the resources of a given area can support (usually through the most unfavourable time of the year)

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7
Q

What are the 3 distribution patterns?

A

uniform, random, clumped

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8
Q

Define uniform population distribution

A

the appearance of 1 organism appears to repel another…intense competition

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9
Q

Define random population distribution

A

the location of 1 organism has no effect on the location of another

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10
Q

Define clumped population distribution

A

the presence of 1 organism means there is a high probability of finding another individual of the same species there

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11
Q

Define age structure

A

A representation of the ratio of various age classes

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12
Q

What are the 2 types of population growth curves?

A

J-shaped (geometric) and S-shaped (logistic)

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13
Q

What are characteristics of a J-shaped (geometric) growth curve?

A

exponential growth until population overshoots the carrying capacity then crashes. Fluctuations can be cyclical or chaotic

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14
Q

What are characteristics of a S-shaped (logistic) growth curve?

A

A population at carrying capacity is regulated so the population doesn’t crash

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15
Q

What is a period of exponential growth?

A

A time where essential resources such as food, water, and space are not limiting and the environment is constant. As density increases, demand increases.

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16
Q

What are the 3 conditions that promote geometric growth?

A
  • new habitat or changed conditions (ex. loss of predators, invasive species)
  • Density independent factors (ex. unstable environment conditions)
  • Time lag (ex. prey species increasing faster than predator species and overshooting)
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17
Q

What are the 2 conditions that promote logistic growth?

A
  • Density dependent factors (increased competition and reduced resource availability as the population approaches carrying capacity). Growth rate slows so that it ideally stabilizes around carrying capacity.
  • Stable environment conditions
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18
Q

List 3 reasons why human population has increased over the past 50 years.

A
  • birth rates have always been high
  • death rates have fallen dramatically due to medicines and vaccines, sanitation, and food production
  • green revolution: the use of high yielding varieties, fertilizers, and pesticides
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19
Q

List 5 factors that regulate a population

A
  • predation
  • dispersal
  • stress
  • territoriality
  • disease
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20
Q

Define ecological niche

A

the role of any organism in any given ecosystem. A niche assumes a specific habitat, community, or stage in succession of a community

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21
Q

What is ecological niches a result of?

A

long term genetic adaptation

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22
Q

What are the 2 types of niche partitioning?

A

Specialist and generalist

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23
Q

What are the characteristics of specialists

A
  • tolerate only specific environmental conditions
  • feed on a limited type of food
  • can usually outcompete other species for their designated food source because they are specialized
  • if their food source disappears, they may be too specialized to use other food sources
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24
Q

What are the characteristics of generalists?

A
  • adaptable to different environments and food sources
  • usually less in danger of becoming extinct when conditions vary
  • is usually outcompeted by specialists for a specific food source
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25
Q

What are 3 examples of infraspecific population regulation?

A

competition, dispersal, territoriality

26
Q

What are the effects of competition?

A
  • reduced growth and possibly reduced development
  • increased mortality rates
  • reduced rates of reproduction
  • high density can be stressful to individuals, which may end up effecting their reproductive activity and immune system
27
Q

When is dispersal most common?

A

When population density is high

28
Q

When is dispersal most effective in regulating population?

A

When population density is low or when population is increasing. Dispersal in response to high population density does not effectively regulate population…overpopulation still remains

29
Q

What are 5 other reasons for dispersal?

A
  • relocating to areas with more resources
  • reducing the risk of inbreeding
  • less competition
  • contributes to population expansion
  • aids in persistence of local populations
30
Q

Define home range

A

The area an animal normally covers during its lifetime

31
Q

Do carnivores or herbivores need larger home range? Why?

A

Carnivores. Larger body size means larger range, they need the range to support a large population of prey

32
Q

Define territoriality

A

When an animal or a group of animals defends a part or all of its home range

33
Q

What are 4 characteristics of metapopulations?

A
  • Suitable habitat occurs in discrete patches that may be occupied by local breeding populations
  • Even the largest local population has risk of extinction
  • habitat patches aren’t so isolated that recolonization can’t occur after local extinction
  • dynamics of the local populations are not synchronized
34
Q

Metapopulation persistence depends on what 2 things?

A

patch size and isolation

35
Q

Probability of local extinction (increases/decreases) with smaller patch size and increased isolation

A

increases

36
Q

Probability of colonization (increases/decreases) with patch size and reduced isolation

A

increases

37
Q

What are 5 factors that promote local population persistance?

A
  • habitat heterogeneity
  • large population size in a neighbouring patch (source of immigrants)
  • increased number of local populations
  • high species dispersal/reproduction rate
  • small body size (area can support larger populations
38
Q

What are the 4 types of population interactions?

A

Competition, predation, mutualism, parasitism

39
Q

How are the two organisms affected in competition?

A

both negatively

40
Q

How are the two organisms affected in predation?

A

one positively, the other negatively

41
Q

How are the two organisms affected in mutualism?

A

both positively

42
Q

How are the two organisms affected in parasitism?

A

one positively, the other negatively

43
Q

What are the two types of competition?

A

Intraspecific and interspecific

44
Q

What is intraspecific competition?

A

Competition between individuals of the same species

45
Q

What is interspecific competition?

A

Competition between individuals of different species which usually leads to more specialization

46
Q

What are the 3 outcomes of competition?

A
  • one species always outcompeting the other
  • both species coexist (altered requirement through resource partitioning)
  • both species live in an unstable equilibrium (some times one will survive, sometimes the other will)
47
Q

What is the competitive exclusion principle?

A

two complete competitors cannot coexist

48
Q

What are complete competitors?

A

two species that live in the same place and have exactly the same ecological requirements

49
Q

Define fundamental niche

A

The full range of conditions under which a species can survive and reproduce. Competition from other species often restricts a species to a portion of its fundamental niche

50
Q

Define realized niche

A

the portion of the fundamental niche that the species actually exploits.

51
Q

What are 3 characteristics of predation?

A
  • mutual regulation
  • lag between change in prey population and change in predator population
  • predators that are highly dependent on few prey species are most likely to experience dramatic population fluctuations
52
Q

Name 5 prey adaptations

A
  • chemical defences
  • cryptic colouration
  • warning colouration
  • mimicry
  • behavioural defences
  • structural defences
  • escape strategies
53
Q

Name 5 predator adaptations

A
  • efficient hunting tactics
  • colouration
  • behavioural strategies
  • physical strategies
  • physiological strategies
54
Q

What is mutualism?

A

An obligate relationship in which both species require the relationship in order to increase fitness levels and survive

55
Q

What are 3 examples of mutualism?

A
  • pollinators and flowering plants
  • legumes and nitrogen-fixing bacteria
  • lichen
56
Q

How is pollinators and flowering plants an example of mutualism?

A

the insect will transfer pollen and receive food in exchange

57
Q

What are 3 cues that a flowering plant will use to attract a pollinator?

A
  • visual cues (colour, pattern)
  • nectar guides (colour/patterns that guide them to the nectar)
  • scent cues
58
Q

What are 3 ways that the pollinator is rewarded by the flowering plant?

A
  • nectar rewards
  • pollen rewards
  • behavioural rewards
59
Q

How is legumes and nitrogen-fixing bacteria an example of mutualism?

A

Certain species of bacteria are able to convert atmospheric nitrogen N2 into the nitrate form NO3- that plants can use. In return, the plant supplies food (sugar based materials).

60
Q

How is lichen an example of mutualism?

A

Lichen is made up of algae and fungi. The algae carry out photosynthesis, while the fungi secrete chemicals that break down rock and supply nutrients such as phosphorous and potassium. This is an important first step in soil building process

61
Q

What is parasitism?

A

A relationship in which one organism benefits while the other is negatively affected but not consumed.

62
Q

What is an example of parasitism?

A

Tapeworms and its host

Ecology (7 decks)

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