Lecture 21: Community Structure

Question 1

Community is the sum of

Answer 1

coevolution and interactions of
- predator/prey
- competition
- mutualisms

Question 2

Community

Answer 2

groups of interacting species that occur together at the same place and time

Question 3

What is example of clear division between communities?

Answer 3

Waterline

Question 4

Communities defined by

Answer 4

1. Dominant species
2. Physical characteristics of the environment

Ex. Oak hickory forest, hot springs community

Question 5

Whole food web is a

Answer 5

community

Question 6

Taxonomic affinity

Answer 6

Refers to the degree of similarity between organisms based on their classification within a specific taxonomic group

Question 7

Communities of birds are grouped by

Answer 7

taxonomic affinity

Question 8

Guild

Answer 8

group of species that use the same resources, even though taxonomically distant

Question 9

Ex of Guild

Answer 9

Organisms (bat, bee, hummingbird) foraging for floral resources (nectar and pollen)

Question 10

Functional group

Answer 10

species that function in similar ways, but aren’t necessarily related or use the same resources

Question 11

Ex of functional group

Answer 11

Different phytoplankton (diatom, coccolithophores, dinoflagellate)

Diatom use lots of Si
Coccolithophores use lots of Ca
Dinoflagellates eat bacteria
But they all float around and photosynthesize

Question 12

Species composition

Answer 12

species present in the community

Question 13

Species diversity

Answer 13

measure of variation in species in the community
includes species richness and species evenness

Question 14

Species richness

Answer 14

Number of species

Question 15

Species evenness

Answer 15

Commonness or rareness of the species

Question 16

Shannon Diversity index (H)

Answer 16

incorporates both number and evenness of species

Question 17

Rank abundance curve

Answer 17

To look at whole community at once
Helpful for examining diversity data of real communities

Question 18

Community interactions can be:

Answer 18

1. direct/indirect: exploitative and interference
2. trophic cascade: food web
3. competitive networks

Question 19

Competitive interactions among species include:

Answer 19

Competition intransitivity: competitive network
Competitive/linear hierarchy

Question 20

Competitive intransitivity

Answer 20

rock/paper/scissors
competitive network
in real communities
hot topic in ecology because it’s so hard to explain species coexistence from other theories
data is not very convincing at the moment

Question 21

Keystone species

Answer 21

species that affects the rest of the community disproportionately to the amount of energy that goes through it
Ex. Piaster

Question 22

Foundation species

Answer 22

large or abundant species that have large community wide effects by providing habitat or food
Ex. Trees

Question 23

Engineering species

Answer 23

Species that create an entire habitat
Ex. Beaver create beaver dam

Question 24

Size and abundance and effect of normal species

Answer 24

Small size and abundance
Small effect of species
Ex. Birds

Question 25

Size and abundance and effect of keystone species

Answer 25

Small size and abundance
Large effect of species
Ex. Beaver

Question 26

Size and abundance and effect of foundation species

Answer 26

Large size and abundance
Large effect of species
Ex. Trees

Question 27

What are the 2 community concepts on how communities assembled?

Answer 27

1. Clements: Coevolved superorganisms
2. Gleason: Sum of independent species distributions

Question 28

Clements community concept

Answer 28

Communities assemble almost as superorganisms
Communities are group of species that worked together, with all of the species filling their particular niche to get to a stable end point

Question 29

Gleason community concept

Answer 29

Species differential responses to environmental conditions matter
Each community is unique set of species dependent on particular environment of the place and time

Question 30

How are communities actually assembled?

Answer 30

Mixture of both Clements and Gleasons ideas

Question 31

Fundamental niche

Answer 31

Gleason
Variation in optima generate independent distributions

Question 32

Realized Niche

Answer 32

Clements
Competition: more restricted, separating species
Facilitation: keeping species together

Question 33

Ecology

Answer 33

study of interaction among species (clements) with their environment (gleason)