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Ecology Test 5 > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

name some biotic factors which structures communities?

A

competition, predation, parasitism, disease, behavioural interactions

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2
Q

name some abiotic factors which structures communities?

A

physical disturbance and controls on distribution

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3
Q

physical factors which affect stream communities scales of influence?

A

potential for colonization
trophic related to catchment
species related to microhabitat

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4
Q

trophic structure?

A

relationships between feeding groups

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5
Q

when does competition?

A

when individuals compete for a resource in limited supply

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6
Q

2 forms of competition?

A
  • exploitation and interference
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7
Q

Exploitation competition

A

where food or space are limited

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8
Q

Interference competition

A

aggressive interactions between competitor species/individuals

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9
Q

Resource partitioning

A

when species co exist by portioning a resource but not in direct competition

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10
Q

what type of species is Baetis?

A
  • a fugitive species

- good colonizer, poor competitor

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11
Q

why do some prey only drift at night?

A

to avoid being seen by predators

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12
Q

snags?

A

woody material fallen into rivers e.g. branches

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13
Q

where are predators found?

A

in all predators

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14
Q

relationship between midgefly and caddisfly?

A
  • decreased no. caddisflies, increase in midgefly
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15
Q

what factors affect prey selection?

A
  • size
  • activity
  • time of drifting
  • contrast/visibility
  • prey vulnerability
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16
Q

How do prey reduce encounter rates? (4)

A
  • spatial segregation
  • use of refuges
  • temporal segregation
  • low movement rates
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17
Q

how do prey reduce attack and capture rates?

A
  • detect and flee, see the predator and move very quickly
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18
Q

Name some postcontact morphological features of prey?

A
  • armor, hardened plates and spine
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19
Q

Name some postcontact behaviourall features of prey?

A
  • aggressive response

- thanotsosis

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20
Q

what is thanotosis?

A

a behavioural mechanism by prey organisms where they play dead in hope the predator will release them

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21
Q

What is aposematism?

A

the advertising by an animal to potential predators that it is not worth attacking or eating

22
Q

How does baetis avoid being attacked?

A
  • moves very rapidly so can flee when attacked
23
Q

How do water mites use aposematism?

A
  • use of bright red body colouration to war predators
24
Q

where are gerridae (water striders found)

A
  • in vegetation where fish present

- on open water where fish absent

25
Q

The effects of tout presence on baetis mayflies risk of predation?

A
  • accelerate larval development,
  • resulting in metamorphosis of younger and smaller individuals
  • minimizing the risk of predation at the expense of fecundity
26
Q

fecundity?

A
  • number of offspring
27
Q

Issue of organisms emerging more quickly at a smaller size?

A
  • adults will produce less eggs
28
Q

order of energy in pyramaid?

A
  • plants at base, providing all energy
  • fed on by herbivores
  • predators
  • top predators
29
Q

What occurs in the absence of predators?

A
  • herbivores aren’t under pressure, more of them

- no. plants decrease

30
Q

influence of grazing on periphyton growing on stones

A
  • reduce amount of vegetation ons tone surface
  • opens up new patches
  • algae move in
  • range of species
31
Q

when is the peak production of periphyton?

A

when intermediate amount of grazing occurs

32
Q

What does the ‘harsh-benign’ concept of Peckarsky?

A
  • gradient of streams form harsh to benign physically
33
Q

describe a benign environment?

A

lower levels of disturbance, environment allows for well developed competition/predation effecs

34
Q

what is understood by disturbance?

A

any relatively discrete event in time that removes organisms and opens up space that can be colonized by individuals of the same or different species e.g flood, pollution

35
Q

How are species diversity and level of disturbance related?

A

the higher the level of disturbance, the species richness decreases

36
Q

What is the effect of moderate disturbance on species diversity?

A

you find both competitive and fugitive species

maximum species diversity

37
Q

what is the patch dynamics concept (PDC)?

A
  • disturbance continually opens up patches for colonization and succession and this turnover of patches explain the function of ecosystems
38
Q

Competitive dominant species?

A

poor colonizers, good competitors

39
Q

Ruderal species features (5)

A

weed species
produce lots of species
grow very rapidly
similar to fugitive

40
Q

What is a fugitive species?

A
  • good colonizer

- poor competitor

41
Q

What is a subsidy?

A
  • a subsidy of energy or material between different environments e.g. terrestrial> freshwater
42
Q

Effects of salmon on pristine glacial streams formed by retreating?

A
  • inputs of nutrients C,N and P

- causes growth of alga, riparian vegetation

43
Q

Effects of carcasses on the bank?

A
  • decay enriches the soil with nutrients and potentially enhances riparian vegetation
44
Q

terrestrial invertebrates preferences in the year?

A

more abundant and active in summer months

45
Q

terrestrial invertebrates preferences in the day?

A

the afternoon

46
Q

What type of source are terrestrial invertebrates?

A

allochonous source

47
Q

What is the effects of availability of allochtonous food source on predation?

A
  • can lead to predator increase or predator switching
48
Q

Human intervention on reciprocal subsidies?

A
  • removal of riparian vegattaion

- channel modification

49
Q

limitation of TBI and BMWP biological monitoring methods?

A

only for organic pollution

50
Q

benefit of WHPT biological monitoring method?

A

used as a general measure of pollution (not specific for just organic)

Ecology Test 5 (3 decks)

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