Community Structure

Question 1

Community

Answer 1

Interactions between
populations of species within a
common area

Question 2

Community zones reflect…

Answer 2

changes in species
composition over space

Question 3

Community zones are based on…

Answer 3

dominant species or physical conditions (temp, alt, salinity)

Question 4

Ecotones are

Answer 4

sharp boundaries between zones

Question 5

Ecotones usually have

Answer 5

high diversity of species

Question 6

independent communities

Answer 6

Species can be in a community because they share
similar habitat requirements:

Question 7

interdependent communities

Answer 7

species can be in a community because they
depend on each other:

Question 8

Methods to quantify a community

Answer 8

1) Species richness: number of species
2) Abundance: number of individuals of each species
3) Rank-abundance curves
4) Species diversity indexes

Question 9

Abundance normally shows a

Answer 9

log-normal distribution

Question 10

The majority of species
show

Answer 10

intermediate values
of abundance

Question 11

Rank-abundance curves illustrate

Answer 11

both species
richness and species evenness

Question 12

Species richness

Answer 12

number of species (points)
within each community

Question 13

Species evenness

Answer 13

comparison of the
relative abundance of each species in
a community

Question 14

Maximum evenness:

Answer 14

all species have
the same relative abundance

Question 15

Simpson’s varies between

Answer 15

1 (if S = 1) and S

Question 16

Shannon’s varies between

Answer 16

0 (if S = 1) and ln S

Question 17

Factors affecting species richness

Answer 17

1) Resources
2) Habitat diversity and connectivity
3) Presence of keystone species
4) Frequency and magnitude of disturbances

Question 18

Most common pattern for species richness

Answer 18

Hump shaped
(stl arch shape)

Question 19

Higher habitat diversity and connectivity

Answer 19

increase species richness

Question 20

More diverse habitats can offer more

Answer 20

potential niches

Question 21

More connected habitats promote

Answer 21

dispersal

Question 22

Keystone species affect the ____ despite not being very abundant

Answer 22

structure of a community

Question 23

keystone species considered ecosystem engineers

Answer 23

beavers

Question 24

Intermediate levels of disturbance maintain

Answer 24

more diverse communities

Question 25

Food chain:

Answer 25

linear representation of species that consume each other (transfer of energy and nutrients).

Question 26

Food web:

Answer 26

all possible feeding relationships among the species of a community (way more realistic).

Question 27

Trophic levels

Answer 27

help understanding food webs with high species richness

Question 28

Terciary consumers

Answer 28

top predators: large carnivores that consume herbivores and mesopredators; parasites

Question 29

Secondary consumers

Answer 29

(mesopredators: small carnivores that consume herbivores; parasites, parasitoids)

Question 30

Primary consumers

Answer 30

(herbivores, parasites, parasitoids)

Question 31

Producers

Answer 31

(mostly photosynthesis: plants, algae)

Question 32

Guilds

Answer 32

group species feeding on similar items within each trophic level

Question 33

Trophic cascade

Answer 33

(indirect effects initiated by a predator)

Question 34

Indirect effects can even happen

Answer 34

between neighboring communities

Question 35

Bottom-up control:

Answer 35

the abundance of trophic groups is determined by the energy available from producers.

Question 36

Top-down control:

Answer 36

the abundance of trophic groups is determined by the existence of top predators.