Post-Exam 2: W12D1 Community Ecology

Question 1

metapopulation

Answer 1

Non-continuous, connected (by gene flow!) populations characterized by
frequent extinction and colonization events
Often source-sink dynamics
It is NOT a “population of populations”

Question 2

Community Structure

Answer 2

The kinds and relative abundance of
species in each community

Question 3

(community structure): Species Richness

Answer 3

number of
species in a given area (usually for
same taxonomic group like plants)

Question 4

(community structure): species evenness

Answer 4

combines both
species richness and relative
abundance of each species

Communities with more species, and
the numbers of those species are
more even (similar numbers) are
considered to be more diverse
Determining community structure

Question 5

(species interaction): commensalism

Answer 5

+, 0
an association between two organisms in which one benefits and the other derives neither benefit nor harm.

Question 6

(species interaction): amensalism

Answer 6

0, -
the two-species interaction in which the impact of one species on the other is negative, but where there is no detectable impact of the second species on the first
0, -

Question 7

(species interaction): competition

Answer 7

-,-
an interaction between organisms or species in which both require a resource that is in limited supply (such as food, water, or territory)

Question 8

(species interaction): mutalism

Answer 8

+,+

Question 9

(species interaction): parasitism

Answer 9

+,-

Question 10

(species interaction): herbivory

Answer 10

+,-

Question 11

(species interaction): predation

Answer 11

+,-

Question 12

food web: trophic interactions (tell me them from bottom to top)

Answer 12

Bottom to top:
also below is decomposers (mushrooms)(detritivores: consume dead and decaying organic matter known as detritus to obtain energy and nutrition)
primary producers (the plants, berries)(autotrophs-an organism that can produce its own food using light, water, carbon dioxide, or other chemicals)–>
primary consumers (the bison, elk, beaver)(heterotrophs-an organism that eats other plants or animals for energy and nutrients) –>
omnivores(bear, raven, coyote)–>
secondary and tertiary consumers(gray wolf, weasel)(heterotrophs)

Question 13

biotic

Answer 13

living things within an ecosystem; such as plants, animals, and bacteria

Question 14

abiotic

Answer 14

non-living components; such as water, soil and atmosphere

Question 15

bottom up determinants of community structure

Answer 15

bottom up factors (a lower trophic level that affects community structure of higher trophic levels by means of resource restriction):
* Drought years
* Change the nutrient availability (N, P, etc.)
* These changes in primary producers influence all the
trophic levels above them

Question 16

top down determinants of community structure

Answer 16

(species occupying the highest trophic level (top carnivores) exert a controlling influence on species at the next lower level (their prey) and so forth down the trophic ladder)
– Change in predator affects whole community
(Yellowstone – wolves)
– Trophic cascades

Question 17

species that outsized roles for community structure

Answer 17

• Dominant species: most common
  ○ Communities named for them
  (often, not always)
• Foundational species: species that
  other species grow on or depend on;
  often dominant species
  ○ Eg, the trees in a forest, giant kelp,
  corals
• Ecosystem engineers: species that
  influence community structure by
  creating/modifying their environments
• Eg, beavers, elephants
• keystone species (next card)

Question 18

keystone species

Answer 18

Species that
have a disproportionate effect on
community structure based on their
abundance
e.g: Sea otters eat sea urchins
sea urchins eat kelp
no otters, no kelp
no kelp, no many, many other
species

Question 19

just to know: trophic levels & energy transfer

Answer 19

only abt 10% of each level’s absorbed energy is absorbed by the next one

Question 20

disturbance impacts on community structure

Answer 20

• Disturbance: any event that removes biomass from a community.
  – Either natural or anthropogenic
  – Vary in frequency and intensity
• Disturbance regime: typical frequency and intensity of
  disturbances for a community.

Question 21

how fires can increase diversity

Answer 21

• Release nutrients
• Open space/reduce
  competition
• Reduce shading
• Limits herbivory