module 13

Question 1

Community

Answer 1

Association of interacting species inhabiting some defined area.

Question 2

Community Structure

Includes attributes such as:

Answer 2

Number of species
Relative species abundance
Species diversity

Question 3

Guild

Answer 3

Group of organisms that all make their living in the same fashion.
Seed eating animals in the desert.

Question 4

Life Form

Answer 4

grouped together based on Combination of structure and growth dynamics.

Question 5

How Diverse Is the World?

Answer 5

2 million Species Identified
As Many as 30 Million plants & Animals
Many more Bacterial Species

Question 6

Biodiversity

Answer 6

The Variety of types of organisms, habitats, and ecosystems on earth or in a particular place

• Genetic Diversity-natural selection, how many different ales, genes
• Species, Genera, or Family Diversity
• Ecosystem Diversity-various diff habitats

Question 7

Diversity in Geologic Time
background extinctions
mass extinctions
times of tremendous radiation of taxa

Answer 7

Constant Species Turnover

• Background Extinctions-every species has extinct or will go extinct in the future, extinction is normal
• Mass Extinctions-loosing large portion of species found in the world
• Times of Tremendous Radiation of Taxa-when one group declines other increases, radiate out and fill niches

Question 8

Latitudinal Gradients in Diversity-diversity increases in

Answer 8

Diversity increases with lower latitudes

Especially within Taxa

Question 9

Species Diversity in US
mammals
avian species
reptiles and amphibians

Answer 9

-Mammals
More Diverse in West
-Avian Species
Similar Pattern
-Reptiles & Amphibians
More Diverse in East

Question 10

Habitat & Physical Conditions
Variation Occurs within Regions
more diverse=

Answer 10

Variation Occurs within Regions
Habitat Structure
Heterogeneity of Habitat
Variation in Primary Production
more variations more heterogenous

Question 11

relative abundance

Answer 11

Relative Abundance

• Number of Individuals of a Species as a percentage of individuals of all Species
• Regularities in the relative abundance of species in communities that hold regardless of the ecosystem.

Question 12

Relative Abundance
Few species are
exaggerated by

Answer 12

Few species are abundant
Most species Relatively Rare
-Small portion of biomass or # of individuals
-Exaggerated by Sampling effect

Question 13

Dominants

generally through

Answer 13

The few species that attain high abundances in a community

Generally through superior Competition

Question 14

Lognormal Model-veil line

portion of lognormal curve is

Answer 14

Veil Line
Portion of Lognormal Curve < 1
Suggests species exist that were not sampled

Question 15

Two factors define species diversity:

Answer 15

Species Richness
Number of species in the community.

Species Evenness
Relative abundance of species- how they are spread out.

Question 16

Dominants influence

Answer 16

• Single or few species that predominates within community

- Exert Strong influence based on their abundance

Question 17

Abundance alone not always a sufficient measure of dominance

Answer 17

Most numerous may not have most biomass

Virginia deciduous forest
Red maple and dogwood
60% relative abundance 
White Oaks
60% biomass, only 9% relative abundance
-also look at biomass

Question 18

Keystone Species, role of keystone species, removal of keystone species can lead to

Answer 18

Species with low abundance/biomass in community

• Exerts strong effects on structure of community
• Often more than would be expected from its abundance

Role of a keystone species

• create or modify habitats
• influence interactions among other species

Removal of a keystone species can lead to

• changes in community structure
• loss of biodiversity

Question 19

Diversity & Community Functioning

starfish

Answer 19

Species Composition Influenced by Complex Interactions
-Predation often affects competitive interactions

Rocky intertidal zone of the Pacific Northwest

• Many invertebrate herbivores
• —mussels, barnacles, limpets, chitons
• Starfish prey on all of these groups

starfish lessen the effects of competition and exclusion allow diversity to stay high

Question 20

Keystone Species: Summation

Answer 20

Keystone species
Exert strong effects on their community structure
Despite low biomass
Function by altering interactions

Dominant Species
Exert strong effects on community structure
Large Biomass
Function through competition

Question 21

Food chain

Answer 21

representation of feeding relationships within a community

Descriptive diagram of flow of energy from prey to predator

Question 22

Food web

Answer 22

Representation of complex interactions of predators and prey

Primary producers form base of the food web

Question 23

Food Webs and Productivity

Trophic Level determined by:

Answer 23

Position determined by # of energy transfers
-from primary producers to current level:
Primary producers
-First level.
Primary consumers
Secondary consumers
Tertiary consumers

Question 24

types of Control of Primary Production

Answer 24

Bottom-up Controls
-Physical and Chemical factors that influence Primary Production
—Lower Trophic levels Control Higher
—Ecosystem Function
Terrestrial Environments
-Temperature and Moisture
Aquatic Environments
-Nutrients Availability
—Phosphorous in Freshwater; Nitrogen in Saltwater
Top Down Controls
-Consumers May Influence Primary Production

Question 25

Carpenter

Answer 25

Proposed piscivores and planktivorous fish can cause significant deviations in primary productivity.

Question 26

Carpenter and Kitchell | came up with what hypothesis

Answer 26

Proposed the influence of consumers on lake primary productivity propagate through food webs. Trophic Cascade Hypothesis

Question 27

top-down effects largest in impact less when

Answer 27

Top-Down Effects - Trophic Cascade - Largest in low Diversity Systems - Impact Less when: - --Choices in Food Items Increases - --Specialization of Upper Trophic Levels Increase - --Stabilizes System

Question 28

Environmental Complexity -species diversity increases when environmental complexity or heterogeneity MacArthur

Answer 28

in general: -Species diversity increases with environmental complexity or heterogeneity. MacArthur ---Environmental complexity = foliage height. ---Warbler diversity increased as vegetation stature increased. -Many studies have shown positive relationship between environmental complexity and species diversity. --Environmental Complexity -> More Habitats More Habitat Space

Question 29

Niches and Diversity of Algae and Plants | -why is there coexistence?

Answer 29

- Hutchinson: - Phytoplankton communities - -Present a paradox - ---Live in relatively simple environments - ---Compete for the same nutrients - ---Yet many species coexist without competitive exclusion. - Environmental complexity may account for significant portion of the diversity.

Question 30

algal niches

Answer 30

Algal niches - Appear to be defined by small shifts in balance of nutrient requirements. - Tilman found: - --Coexistence of freshwater diatoms depended upon ratio of silicate and phosphate. - -Found conditions allowing coexistence. - -----Diatoms held different trophic niches. - ----Thus different diatoms would dominate different areas.

Question 31

Diversity & Primary Production

Answer 31

Production ->More Energy -> More Species? Sometimes True May be Correlated Not Determinant

Question 32

Algal & Plant Diversity & Increased Nutrient Availability -adding nutrients to water or soils ____ diversity and ____competition

Answer 32

- Nutrient availability & Diversity - --Negative relationship - --Adding nutrients to water or soils - ----Generally reduces diversity of plants and algae. - ----Reduces number of limiting nutrients - --------Increases Competition

Question 33

Paradox of Enrichment | production and diversity are often ____ correlated

Answer 33

Diversity & Production often negatively Correlated -Habitat Heterogeneity Monocultures often most Productive Dominant Species Extremely successful

Question 34

Disturbance

Answer 34

Difficult to define Involves departure from “average conditions.” Average conditions may involve substantial variation.

Question 35

Sousa defined disturbance:

Answer 35

Discrete, punctuated, killing, displacement, or damaging of one or more individuals that directly or indirectly creates an opportunity for new individuals to be established.

Question 36

Disturbance and Diversity white and Pickett two major characteristics

Answer 36

``` White and Pickett defined disturbance: -Any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment. -Two major characteristics: Frequency Intensity ```

Question 37

Intermediate Disturbance Hypothesis

Answer 37

Connell - Disturbance is a prevalent feature that significantly influences community diversity. - Both high and low levels of disturbance would reduce diversity. - Intermediate levels promote higher diversity. - --Sufficient time between disturbances: - -----Allows wide variety of species to colonize - -----But not long enough to allow competitive exclusion.

Question 38

Dynamic Equilibrium Model

Answer 38

Interaction between the extent of disturbance in a community and the rates of population growth of species in the community determines diversity