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ecology and conservation > community ecology & functional roles > Flashcards

community ecology & functional roles Flashcards

1
Q

ecological community

A
  • all pops of all species living close enough for actual (or potential) interaction
  • includes direct & indirect interactions
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1
Q

direct and indirect interaction example

A

direct: catapillar grazing on leaf

indirect: effect of catapillar parasites on plant

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2
Q

5 interaction examples

A
  1. Competition
  2. Predation
  3. Herbivory
  4. Parasitism
  5. Mutualism -> both species are mutually benefited
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3
Q

interspecific competition

A

2 or more species competing for the same limited resource

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4
Q

keystone species

A
  • not most abundant species
  • helps define ecosystem
    -> without species: ecosystem would be dramatically diff / cease to exist!!
  • eg. sea otters
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5
Q

functional groups of communities examples?

A
  • canopy community
  • grazer community
  • decomposer community
  • tree community
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6
Q

sp interactions

A
  • help
  • no effect
  • hinder
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7
Q

interspecific interactions

A

interactions between species in a community

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8
Q

interspecific competition

A

2+ sp competing for same limited resource

  • resource limits survival & reproduction of both individs
  • competition has a -ve impact on both/all interacting sp
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9
Q

What happens in community when 2 species compete for limited resources?

include example

A

competitive exclusion

-> strong competition can lead to exclusion of a sp (Gause 1934)

example: lab experiments on 2 protozoa species:

  • Grown independently both sp thrive
    -> rapidly increase then level off at carrying capacity
  • Grown together, 1 sp driven to extinction

-> inference: 1 sp had a competitive edge in obtaining food

-> CONCLUSION: 2 sp who compete for same limiting resources cannot coexist permanently in same place

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10
Q

ecological niches

(the type of niches possible)

A

set of biotic & abiotic resources that a sp uses in its env

  1. tolerances e.g. temp, salinity
  2. habitat e.g. substrate on which it grows, timing of active
  3. resource requirements e.g. type & size of prey it eats
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11
Q

suggest how so many species can co-exist despite competition?

(use niches)

A

sp can co-exist if…

  • suff diff in niche requirements
    OR
  • if their niches can change
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12
Q

fundamental niche

A

niche sp could potentially occupy

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13
Q

realised niche

A

niche sp actually occupies

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14
Q

7 sp of Anolis lizards all live in the same area and all feed on insects and other small arthropods.

How do they all survive?

A

niches are differentiated

-> competition is ↓ as they all have diff perches

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15
Q

suggest 2 ways niches can be partitioned

A
  • space
  • time
16
Q

example of niches partitioned in time

A

common spiny mouse (nocturnal) & golden spiny mouse (diurnal) co-exist

  • ‘golden’ is naturally nocturnal -> changes biological clock to be diurnal when ‘common’ present
  • this behaviour change suggests sp were competing & partitioned niches to co-exist
17
Q

how can 2 closely related sp occur?

A
  • allopatry -> geographically separate

^pops are morphologically similar & use similar resources

  • sympatry -> geographically overlapping

^pops show diffs in morphology & resource use – would otherwise potentially compete

18
Q

character displacement

A

(indirect evidence of effects of competition)

  • tendency for characteristics to diverge more in sympatric (same env) than allopatric pops. of 2 sp

aka…

  • change that occurs when 2 similar sp inhabit same env
19
Q

adaptations of predators

A
  • sensory apparatus
    -> forward-facing eyes
    -> heightened visual & auditory acuity
    -> heat sensing organs
  • catching, killing, subduing prey
    -> claws
    -> teeth / fangs / beaks
    -> stings
    -> poisons
    -> behaviours
    -> webs / traps
20
Q

adaptations of prey

A
  • behavioural adaptations
    -> fleeing
    -> group living
    -> self / group defense
    -> hiding
  • morphological / physiological adaptations
    -> swift & agile
    -> horns & spines
    -> noxious secretions
    -> bright colours
    -> autotomy (self-amputation)
21
Q

colour adaptations

A
  • crypsis colouration -> makes prey difficult to see
  • aposematic (warning) colouration -> predators avoid bright colours
22
Q

Batesian Mimicry

A

palatable / harmless sp mimics unpalatable / dangerous sp

e.g. caterpillar mimicking a snake

evolves via natural selection…

  • individs in harmless sp that happen to more closely resemble harmful sp are avoided by predators that have learned to avoid harmful ones
  • closer resemblance evolves via this selection pressure
23
Q

Müllerian Mimicry

A

2+ unpalatable sp mimic each other

eg. Heliconid Butterflies & Poisonous (Cyanide) Aposematism

  • shares cost of predation as predators learn avoidance…
  • the more unpalatable prey there are, the faster predators learn to avoid prey with that appearance
  • mimic each other’s honest warning signals, to their mutual benefit
24
Q

dom species

A
  • most abundant / have highest biomass in a community
  • exert strong ecological effect as result of being highly abundant
    -> e.g. impacting light levels, nutrient levels and water availability to other sp
25
Q

What causes a species to become dominant within a community?

A

2 main hypotheses:

  • dom sp are more competitive at obtaining resources
  • dom sp are better at avoiding predation / disease
26
Q

invasive / alien sp example

A

Signal crayfish

  • In Europe, crayfish plague (caused by water mould Aphanomyces astaci) was damaging European crayfish stocks
  • Signal crayfish were imported from
    N America->Europe to allow recreational & commercial crayfish capture
  • Signal crayfish: unknown carrier of crayfish plague, but suffers low mortality from pathogen
  • to European sp: infection is fatal
  • Signal crayfish acted as disease reservoir from which European sp were infected – is now a problematic invasive
27
Q

We can measure the impacts a dom sp has on a community if it is removed.

example?

A

American chestnut -> dom sp in N. American deciduous forests up to 1910 (>40% of mature trees)

  • chestnut blight: fungal infection introduced into US via imported timber from Asia
    -> 1950 ~ all American chestnut trees gone

mixed effect on other species…

  • Oak, Hickory Beech & Red Maple ↑ abundance
  • mammals & birds unaffected
  • 7/56 moth & butterfly sp that fed on American chestnut became extinct
28
Q

How to research species removal?

A
  • natural experiments (e.g. Zostera)
  • humans removing dom. sp e.g. clearing land for agriculture
  • mathematical modelling
  • microcosm experiments
29
Q

evidence of sea otters being a keystone species

A

In Alaska, sea otters are predator of sea urchins

  • sea urchins eat kelp roots
  • where sea otters abundant: kelp forests abundant
  • where sea otters less abundant: kelp is v rare

BUT… Orca predation becoming ↑ common on Sea Otters…

  • ↓in Harbour Seal & Steller’s sea lion (Orcas typical prey) -> sea otter pop ↓
  • sea urchin pop ↑
  • loss of kelp forest?
30
Q

foundation sp / ecosystem engineers

A

animals that physically alter their env rather than via trophic interactions

eg. beavers…

  • fell trees & create dams
  • clearing forest & creating large areas of flooded wetlands
31
Q

Beavers can have a cyclic effect on rivers and streams.

explain this

foundationn sp

A
  • abandoned Beaver ponds “silt up”
  • eventually dams breach leaving wetland habitat
  • Riparian tree sp re-colonise & beavers return
32
Q

knowledge of top-down and bottom-up control enables us to solve ecological problems.

what ecological problems?

A
  • many freshwater lakes in/near industrial / urban areas suffer from pollution (sewage & fertilizer run off)

^result in poor water quality

  • ↑ nutrient levels => growth of algae and cyanobacteria (harmful algal blooms)
33
Q

Knowledge of Top-Down and Bottom-Up control enables us to solve ecological problems.

case study?

A

Lake Vesijärvi in Finland

  • highly polluted from industrial & household waste
  • in 1976, industrial regulation stopped pollution entering lake
  • water quality started to ↑ BUT later huge blooms of cyanobacteria (blue- green algae) began

MORE INFO IN BOOK NOTES

34
Q

biomanipulation

A
  • adding / removing sp from ecosystem…
  • to achieve a +ve change in env

ecology and conservation (9 decks)

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