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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
dom species
- **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
What causes a species to become dominant within a community?
2 main hypotheses: - dom sp are **more competitive** at obtaining resources - dom sp are **better at avoiding predation / disease**
26
invasive / alien sp example
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
We can measure the **impacts a dom sp has on a community** if it is **removed**. example?
**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
How to research species removal?
- natural experiments (e.g. Zostera) - humans removing dom. sp e.g. clearing land for agriculture - mathematical modelling - microcosm experiments
29
evidence of **sea otters** being a keystone species
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
foundation sp / ecosystem engineers
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
Beavers can have a cyclic effect on rivers and streams. explain this | foundationn sp
- abandoned Beaver ponds **“silt up”** - eventually **dams breach leaving wetland habitat** - Riparian tree sp **re-colonise** & beavers **return**
32
knowledge of top-down and bottom-up control enables us to solve ecological problems. what ecological problems?
- 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
Knowledge of Top-Down and Bottom-Up control enables us to solve ecological problems. case study?
**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
biomanipulation
- **adding / removing sp** from ecosystem... - to achieve a **+ve change in env**

ecology and conservation (9 decks)

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