Community ecology

Question 1

How do mutualisms evolve?

Answer 1

Initially antagonistic

Question 2

Pollen example for evolution of mutualism

Answer 2

pollen feeding led to incr pollen transfer
Pollen with mechanisms to attract pollinators (eg nectar) and ensure pollen transfer more success
Pollinator specialized to transfer pollen and get resources from host, incr success by gaining resources not available to other pollinators

Question 3

Obligate symbiotic

Answer 3

both species live in permanent close relationship eg lichen =
fungi and algae and/or cyanobacteria, eg 2 mitochondria

Question 4

community

Answer 4

association of interacting populations, defined by nature of their interaction and/or the place in which they live

Question 5

‘communities as superorganism’

Clements

Answer 5

proposition that communities are like ‘super organisms’, where species bound by interactions. Also referred to as a closed community

Question 6

closed community

Answer 6

clear and relatively sharp community boundaries

Question 7

What did Gleason argue

Answer 7

Communities are associations of species assembled by chance, independent of other species presence or absence, aka ‘open community’

Question 8

open community

Answer 8

community boundaries indistinct, species should have independent boundaries

Question 9

What might appearance of closed communities be due to

Answer 9

common environmental needs, instead of interdependence among the species

Question 10

Primary succession

Answer 10

Where communities develop from new, never-before occupied space

Question 11

Secondary succession

Answer 11

communities affected by occurrence of disturbances in recolonization

Question 12

What does studying recolonization of small gaps in a community provide info on

Answer 12

Whether community assembly is deterministic (no randomness) or random

Question 13

Founder controlled

Answer 13

communities where any species has equal chance to colonise gap
Future composition determined by chance
Maintains diversity
Selects for R species (large clutch, fast development)

Question 14

Dominance controlled

Answer 14

Species differ in competitive ability
Outcome predicted by competitiveness, although undergoes succession often
Maintains less diversity
Initially selects for R, but K species eventually dominates

Question 15

2 ways to quantify/describe differences between communities

Answer 15

Species composition/diversity

Trophic structure

Question 16

Species richness

Answer 16

count number of species in given area

Question 17

Problem with species richness

Answer 17

ignores species evenes

Question 18

Shannon index

Answer 18

Incoorporates richness and eveness

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Question 19

Trophic structure

Answer 19

… of a community is determined by feeding relationships between organisms

Question 20

food chain/web def

Answer 20

Transfer of food energy from its source in photosynthetic organisms through herbivores and carnivores

Question 21

Order of trophic levels (summary)

Answer 21

producers/plants
herbivores
carnivores

Question 22

What factors affect trophic structure/number of levels of communities

Answer 22

Bottom up regulation

Top down regulation

Question 23

Bottom up regulation

Answer 23

Imperfect transmission of energy, controlled by primary production
Means higher levels (carnivores) smaller.
Size of trophic level determined by by rate of production of its food resource

Question 24

Top down regulation

Answer 24

when higher trophic levels determine size of trophic levels below them

Question 25

Keystone species

Answer 25

species that have a disproportionate effect on the community

Question 26

Why is it important to identify keystone species

Answer 26

avoid incorrectly managing species