Lecture 16: Community Ecology & Structure

Question 1

Original greek word for Ecology

Answer 1

“Oekologie”

-comes from greek work “Oikos” meaning house

Question 2

definition of ecology (basic definition)

Answer 2

study of the household of nature

Question 3

Ecology (official definition)

Answer 3

study of relationships between living organisms and their physical surroundings

Question 4

Different types of ecology

Answer 4

• Biosphere
• Ecosystem
• Community
• Population
• Individual
• Molecular

Question 5

Population

Answer 5

a group of individuals of a single species living close together at the same time.

SAME SPECIES SAME PLACE SAME TIME

Question 6

Community

Answer 6

all populations together in one place including plants, fungi, animals, protists, etc.

Question 7

Ecosystem

Answer 7

the community along with the physical, non-living environment.

Question 8

Biosphere

Answer 8

“sum of all ecosystems”: ecosphere, lithosphere, atmosphere, and hydrosphere

Question 9

Biome

Answer 9

groupings of many ecosystems often characterized by climate and dominant plants.

Question 10

Trophic approach organizes species based on…

Answer 10

trophic or energetic interactions

Question 11

What are the downsides of the trophic approach?

Answer 11

Trophic approach does not…

• Quantify the strength of interactions or their importance in the community.
• Handle species that span two trophic levels, change feeding status as they mature, or are omnivores.
• Include non-trophic interactions (e.g., horizontal interactions, such as competition).
• Community approach does!

Question 12

Community approach organizes species by:

Answer 12

a) physical characteristics or environment (e.g., mountain stream, sand dune, desert, etc.)
b) biological characteristics emphasizing dominant species (e.g., trees, kelp, etc.)

Question 13

How do we characterize communities?

Answer 13

Structure
1) Community Structure: the types and numbers of species (or subsets of species) present

Dynamics
2) Community Dynamics: how communities change over time

Question 14

Taxonomic affinity

Answer 14

relationship or resemblance in a taxonomic sense

e.g., all bird species in a community

Question 15

Guild

Answer 15

group of species that use the same resources

Question 16

Functional group

Answer 16

species that function in similar ways, but do not necessarily use the same resources

Question 17

Subsets of species

Answer 17

• Taxonomic affinity
• guild
• functional group

Question 18

Types of species

Answer 18

• Foundation Species
• Keystone Species
• Dominant Species

Question 19

Foundation Species

Answer 19

Causes physical or chemical changes in environment, affecting other species.

Question 20

Keystone Species

Answer 20

Controls distribution or abundance of other species, but not necessarily most abundant.

Question 21

Dominant Species

Answer 21

Most abundant in either numbers or biomass and affect numbers or distribution of other species (e.g., better competitors or resist predation).

Question 22

3 ways to measure community structure

Answer 22

• Species Richness
• Species Evenness
• Species Diversity

Question 23

Species Richness

Answer 23

the number of species in a community.

ie-Count the number of different species in the box.

Question 24

Species Evenness

Answer 24

relative abundances compared with one another.

Question 25

Species Diversity

Answer 25

combines species richness and species evenness (measures community complexity).

Question 26

How do we measure species diversity?

Answer 26

• By combining species richness and species evenness.
• Most commonly used method is an index called the Shannon index
• Lower values of shannons index = lower diversity

Question 27

What does Species Accumulation Curve tell us?

Answer 27

These curves can help determine when most or enough of the species in a community have been observed. (adequately sampled)

Question 28

What influences community structure?

Answer 28

1. Climate patterns of the community’s location.
2. Geography of the community’s location.
3. Heterogeneity (patchiness) of the community’s location.
4. Frequency of disturbances, or disruptive events.
5. Interactions between organisms.

Question 29

How do climate patterns affect community structure and dynamics?

Answer 29

• altered community composition
• rewiring of food webs
• changes in food web stability
• altered dispersal patterns
• altered ecosystem functions(decomposition rates)

Question 30

Biodiversity

Answer 30

describes diversity at multiple spatial scales

Question 31

temporal mismatch

Answer 31

shifts in phenology induce temporal mismatches

-ie flower and bee

Question 32

spatial mismatch

Answer 32

species range shifts induce spatial mismatches

-ie species moves higher up on mountain

Question 33

body size mismatch

Answer 33

changes in body size induce size mismatches

-ie shrinking bug can no longer eat its prey

Question 34

“Intermediate Disturbance Hypothesis”.

Answer 34

Communities with moderate frequency of disturbances have the most species diversity whereas low and high frequency disturbances have low species diversity.