Community Structure

Question 1

interdependent communities

Answer 1

species in a community depend on each other to exist
-distinct community boundaries

Question 2

independent communities

Answer 2

species in community do not depend on each other to exist
-no distinct community boundaries

Question 3

ectotone

Answer 3

region of rapid replacement of species along an environmental gradient

Question 4

soil-driven ectotone

Answer 4

serpintine soils
-low in nutrients, high in toxic heavy metals

Question 5

quantifying communities

Answer 5

-the number of species in a community (species richness)
-abundance of each species

Question 6

relative abundance

Answer 6

-proportion of individuals in a community represents by each species
-long-normal distribution (bell curve after a log transform)

Question 7

species evenness

Answer 7

the degree of similarity in relative abundance of species in a community

Question 8

diversity indices

Answer 8

measures of diversity that increase with species richness and evenness
- calculated from species relative abundances

Question 9

keystone species

Answer 9

a species that substantially affects community structure despite low relative abundance

Question 10

omnivore

Answer 10

a species that feeds on several trophic levels

Question 11

guild

Answer 11

within a trophic level, a group of species that feed on similar items

Question 12

direct effects

Answer 12

an interaction between two species that does not involve other species

Question 13

indirect effects

Answer 13

an interaction between two species that involves one or more intermediate species

Question 14

trophic cascade

Answer 14

influence of consumers or producers on populations that are 2 or more trophic levels removed

Question 15

top-down control

Answer 15

influence of predators on the sizes of the trophic levels below them in the food web

Question 16

bottom-up control

Answer 16

influence of producers on the sizes of the trophic levels above them in the food web