Unit II: Community Ecology

Question 1

There is a general ______ correlation between niche overlap and competition intensity

Answer 1

positive (*on a graph, it is a positive slope)

Question 2

What is Niche?

Answer 2

range of resources used and conditions tolerated

Question 3

What is Fundamental Niche?

Answer 3

theoretical range of environment conditions that a species can tolerate (max & min)

Question 4

What is Realized Niche?

Answer 4

portion of the fundamental niche that is actually occupied/the resources actually used in nature (given limiting factors)

Question 5

Can the Realized Niche be bigger than the Fundamental Niche?

Answer 5

No, the realized niche is small because it’s in competition with other species in nature

Question 6

What happens when two species in a community have overlapping niches?

Answer 6

This will only happen if species are equal.
1. Competitive Exclusion Principle
2. Niche Differentiation
3. Resource Partitioning

Question 7

What is Competitive Exclusion Principle?

Answer 7

no 2 species within a habitat can coexist when they compete for the same resources at the same place and time
- one species outcompetes the other (asymmetric competition)
- local extinction of weaker competitor

Question 8

In competition exclusion, the fitness is ____ where the two species’s fundamental niche overlap

Answer 8

low, only the superior species can get the niche overlapping in fundamental niche because natural selection selects against individuals that compete

Question 9

What is Resources Partitioning?

Answer 9

change in resource use caused by competition over generations

Question 10

What is Niche Differentiation?

Answer 10

when 2 species separate out of the niche space in which they overlap

Question 11

What is Character Displacement?

Answer 11

evolutionary changes in traits that make niche differentiation possible (e.g. change in body size)

Question 12

When does character displacement occur?

Answer 12

happens when species are sympatric with a competitor, therefore the species will have different body types because they’re in competition

Question 13

What is Sympatric?

Answer 13

overlapping in an area

Question 14

What is Allopatric?

Answer 14

in separate areas (geographically)

Question 15

When species are allopatric, this means they are not in ________, and the species will have very similar body sizes.

Answer 15

competition

Question 16

What is Mimicry?

Answer 16

when one species resembles another

Question 17

What is Bayesian Mimicry?

Answer 17

when a harmless/patable species mimics a dangerous/unpalatable species

Question 18

Who is the Bayesian Mimicry names after?

Answer 18

Henry Walter Bates (Wallace’s companion in Brazil)

Question 19

What is Müllerian Mimicry?

Answer 19

2 or more harmful species mimic each other

Question 20

Who discovered müllerian mimicry?

Answer 20

Fritz Müller

Question 21

What is Emsleyan (Mertensian) Mimicry?

Answer 21

type of mimicry where a harmful (deadly) species resembles a less harmful one

Question 22

How do predators protect the Emsleyan/Mertensian Mimicry?

Answer 22

predators develop learned avoidance of the less harmful model, in order to protect the deadly mimic

Question 23

What is Aggressive Mimicry?

Answer 23

when a predator mimics a desirable species (e.g. venus fly trap-pretty flower)

Question 24

What is a Foundation Species?

Answer 24

species which often forms the major structural portion of the habitat; usually the primary producers (e.g. coral reefs)

Question 25

What is Succession?

Answer 25

sequence of changes in communities occupying an area after an environmental disturbance or the creation of a new substrate

Question 26

At what stage of succession, do species alter the environment?

Answer 26

each stage, in which a new species in introduced or changes (e.g. as a new tree grows in, less sunlight becomes available)

Question 27

Succession is impossible to predict. True of False?

Answer 27

False, the changes of succession are often predictable

Question 28

What are the 3 ways an existing species may affect the species which follows them in introduction?

Answer 28

1. Facilitation: conditions become favorable
2. Tolerance: no effect
3. Inhibitation: hinders establishment

Question 29

What is Climax Community?

Answer 29

the final stage of succession, where a stable community is formed by a characteristic assortment of plant and animal species; species are tolerant of competition with each other

Question 30

What are the 2 types of Succession?

Answer 30

1. Primary Succession
2. Secondary Succession

Question 31

What is Primary Succession?

Answer 31

succession on land that previously had no life

Question 32

What is Secondary Succession?

Answer 32

succession in response to environmental disturbances that move a community away from its equilibrium

Question 33

What is a Pioneer Species?

Answer 33

1st species to appear in primary and secondary succession

Question 34

What are characteristic of a pioneer species?

Answer 34

• “weedy”
• high rmax
• devote more energy to reproduction than competitive ability