52 Community Ecology

Question 1

What are the four most common types of interactions among species?

Answer 1

Commensalism, competition, consumption, mutualism

Question 2

Commensalism

Answer 2

species relationship where one organism (the commensal) benefits and the other (the host) is unaffected

Question 3

Competition

Answer 3

interaction of 2 species or 2 individuals trying to use the same limited resource (e.g. water, food, living space), resulting in lower fitness for both; may occur between individuals of the same species (intraspecific) or different species (interspecific)

Question 4

Consumption

Answer 4

interaction between species where one organism eats or absorbs nutrients from another (e.g. predation, herbivory, parasitism), increasing the consumer’s fitness but decreasing the victim’s fitness

Question 5

Mutualism

Answer 5

species relationship between 2 organisms (mutualists) that benefits both

Question 6

3 key themes of species interactions

Answer 6

(1) Species interactions can affect the distribution and abundance of a particular species (2) Species act as agents of natural selection when they interact (3) The outcome of interactions among species is dynamic and conditional

Question 7

Coevolution

Answer 7

A pattern of evolution in which 2 interacting species reciprocally influence each other’s adaptations over time

Question 8

Intraspecific competition

Answer 8

competition between members of the same species for the same limited resource; intensifies as population density increases

Question 9

Interspecific competition

Answer 9

competition between members of different species for the same limited resource

Question 10

Niche

Answer 10

the range of resources that a species can use and the range of conditions that it can tolerate; the role a species plays in its ecosystem

Question 11

Symmetric competition

Answer 11

ecological competition between 2 species in which both suffer similar declines in fitness; when the niches of 2 species overlap

Question 12

Asymmetric competition

Answer 12

ecological competition between two species in which one species suffers a greater fitness decline than the other depending on the amount of overlap in their niches

Question 13

Competitive exclusion principle

Answer 13

two species cannot coexist in the same ecological niche in the same area because one species will outcompete the other

Question 14

Fundamental niche

Answer 14

total theoretical range of environmental conditions that a species can tolerate

Question 15

Realized niche

Answer 15

portion of the fundamental niche that a species actually occupies given limiting factors such as competition with other species

Question 16

Niche differentiation or resource partitioning

Answer 16

evolutionary change in resource use by competing species that occurs as the result of character displacement

Question 17

Character displacement

Answer 17

evolutionary tendency for the traits of similar species that occupy overlapping ranges to change in a way that reduces interspecific competition

Question 18

Community

Answer 18

all of the populations that interact with one another in a given area

Question 19

Ecological disturbance

Answer 19

any event that removes significant biomass from a community; impact depends on 3 factors: type, frequency, severity

Question 20

Ecological succession

Answer 20

development of a community after a disturbance

Question 21

Primary succession

Answer 21

occurs after a disturbance removes all the biomass and all the soil from an area e.g. volcanic eruptions, glaciers, floods, landslides

Question 22

Secondary succession

Answer 22

occurs after a disturbance removes some or all biomass from an area, but leaves the soil intact e.g. forest fires, logging, construction, farming

Question 23

Pioneer species

Answer 23

high dispersal, weedy/fast growing, short generations, tolerant of harsh conditions; likely to exponential growth but may never reach its carrying capacity

Question 24

Climax species

Answer 24

low dispersal, good competitors, long-lived, require favourable conditions; likely to exhibit logistic growth