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BIO1M03 > chapter 52 - community ecology > Flashcards

chapter 52 - community ecology Flashcards

1
Q

define biological community

A

consists of all the populations of interacting species living within a defined area

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2
Q

4 types of species interactions

A

mutualism
- two species interact in a way that benefits fitness of both (+/+)

competition
- individuals use the same resources, lower fitness for both (-/-)

consumption
- one organism eats/absorbs nutrients from another, increasing consumers fitness, lowering victim’s (+/-)

commensalism
- once species benefits, other unaffected (+/0)

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3
Q

types of competition

A

infraspecific competition (same species)
- density dependant (cause of density dependant growth)
- intensifies as density increases

interspecific competition (different species)
- when members of different species use same limiting resources
- direct (real-time competition) vs indirect

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4
Q

factors that can affect competition

A

niche overlap
- competitive exclusion lowers carrying capacity

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5
Q

fundamental vs realized niche

A

fundamental
- total theoretical niche a species can occupy

realized
- niche species occupies as a result of forces of competition

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6
Q

why would species niches not fully overlap?

A

from their FUNDAMENTAL NICHE, species pushed into their REALIZED NICHE by factors such as competition with other species

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7
Q

competitive exclusion principle

A

when a superior species uses all of its competitor’s resources, causing inferior species to disappear

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8
Q

niche differentiation

A

natural selection against species that compete
therefore removes competitive overlap in niches

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9
Q

fitness tradeoff in competition

A
  • competitive traits are only one aspect of niche
  • therefore, organisms have to trade off other traits, a compromise in adaptation

e.g. organisms good at competing probably struggle with droughts and disease

RESULT: natural selection against individuals that compromise traits (NICHE DIFFERENTIATION)

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10
Q

types of consumption

A
  • herbivory
  • predation
  • endoparasites (live inside host. simple and worm-like)
  • ectoparasites (live outside hosts. harvest fluid)
  • parasitoids (have endoparasite larvae) pa
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11
Q

types of defences

A

constitutive/standing defences
- always present, even in absence of predator

inducible defences
- only present when predator is present

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12
Q

define the two types of mimicry

A

constitutive defenece

  1. Batesian (look dangerous, aren’t dangerous)
    - nontoxic prey species resemble dangerous prey species
    - one species benefits
  2. Müllerian (look dangerous, are dangerous)
    - two harmful prey species resemble each other
    - both benefit
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13
Q

constitutive/standing defences

A

defences always present

  • cryptic colouration/object resemblance
  • escape behaviour
  • toxins and chemicals
  • schooling + flocking
  • defence armour + weapons
  • mimicry (batsman and mülerian)
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14
Q

inducible defences

A
  • traits produced in response to the
    presence of a predator
  • less costly, but take time
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15
Q

parasites

A
  • use consumers as biocontrol agents
  • consumption is an agent of natural
    selection (hosts get eaten, making it easier to spread parasite)
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16
Q

define mutualisms

A

mutually beneficial dynamic species interactions

*mutalism may fail the mutualist:
eg ants and tree hoppers - tree hoppers eat ants predator (spiders), and use ants honeydew. when spiders not present, ants dont benefit, do tree hopper-ant relationship changes to -/+ (consumption)

17
Q

key aspects of community structure

A
  1. total number of species
  2. general types and outcomes of interactions among all species
  3. relative abundance of those species
  4. physical aspects that matter (including biotic/abiotic factors)
18
Q

when multiple consumption interactions are linked…

A

food chain!

19
Q

when multiple food chains are linked…

A

food web

20
Q

trophic cascade

A

series of changes in abundance of species in a food web
usually caused by addition/removal of predator

21
Q

things that impact food webs

A
  • top down influence
  • bottom up influence
  • ecosystem engineers
  • trophic cascade (when impacts propagate down)
22
Q

define a “disturbance” in an ecological community

A
  • strong, short-lived disruption that changes the distribution of living or nonliving resources
    e.g. forest fire, epidemic, flood

impact is a function of
1. type
2. frequency
3. severity

23
Q

define disturbance regimine

A

characteristic disturbances that affect a given community

24
Q

describe how communities can develop after disturbances

A

depends on state of the soil

PRIMARY SUCCESSION
- organisms colonise bare mineral soil

SECONDARY SUCCESSION
- soil is already present so recovery is faster

25
Q

stages of secondary succession

A
  1. pioneering species
    - weedy species
  2. early successful community
    - long-lived herbaceous species
  3. mid-successional community
    - shrubs and short lived trees
  4. climax community
    - long lived trees
26
Q

general development of communities after disturbances

A

early successional communities species
- short lived
- small size
- disperse seeds over long distances

late successional communities species
- long lived
- large
- good competitors for light and nutrients

27
Q

role and types of species interactions in colonization

A
  • succession after colonization depends more on how species interact with each other
  • as species modify habitat, different traits favoured, leads to species replacement

types of interactions:
1. FACILITATION - Existing species help those arriving
2. TOLERANCE- existing species don’t affect arrivals
3. INHIBITION - presence of one inhibits the other

28
Q

define species richness, diversity

A

richness:
# of species present in a given community

diversity:
measure of species relative abundance

definitions used interchangeably

29
Q

immigration and extinction on islands as a function of…

A

distance

immigration decreases as population increases
extinction increases as population increases

30
Q

extinction can be a function of ___

A

distance
the farther species immigrate, the more likely they are to go extinct

31
Q

asymmetric vs symmetric competition

A

ASYMETRIC
- one species suffers more than another

SYMETRIC
- both species suffer fitness loss

32
Q

theory of island biogeography

A

distance

immigration decreases as population increases
extinction increases as population increases

33
Q

global patterns in species richness

A
  • large populations tend to be species rich
  • latitudinal gradient in species diversity
34
Q

hypotheses for species richness

A

many, e.g.

  • high-productivity hypothesis (increased speciation, decreased extinction)
  • area and age hypothesis (historically more time for speciation to occur)
  • environmental variability (eg seasons)

BIO1M03 (11 decks)

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