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ecology exam 2 and 3 > module 13 > Flashcards

module 13 Flashcards

1
Q

Community

A

Association of interacting species inhabiting some defined area.

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2
Q

Community Structure

Includes attributes such as:

A

Number of species
Relative species abundance
Species diversity

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3
Q

Guild

A

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

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4
Q

Life Form

A

grouped together based on Combination of structure and growth dynamics.

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5
Q

How Diverse Is the World?

A

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

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6
Q

Biodiversity

A

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
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7
Q

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

A

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
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8
Q

Latitudinal Gradients in Diversity-diversity increases in

A

Diversity increases with lower latitudes

Especially within Taxa

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9
Q

Species Diversity in US
mammals
avian species
reptiles and amphibians

A 
-Mammals
More Diverse in West
-Avian Species
Similar Pattern
-Reptiles & Amphibians
More Diverse in East
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10
Q

Habitat & Physical Conditions
Variation Occurs within Regions
more diverse=

A 
Variation Occurs within Regions
Habitat Structure
Heterogeneity of Habitat
Variation in Primary Production
more variations more heterogenous
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11
Q

relative abundance

A

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.
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12
Q

Relative Abundance
Few species are
exaggerated by

A

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

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13
Q

Dominants

generally through

A

The few species that attain high abundances in a community

Generally through superior Competition

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14
Q

Lognormal Model-veil line

portion of lognormal curve is

A

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

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15
Q

Two factors define species diversity:

A

Species Richness
Number of species in the community.

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

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16
Q

Dominants influence

A
  • Single or few species that predominates within community

- Exert Strong influence based on their abundance

17
Q

Abundance alone not always a sufficient measure of dominance

A

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
18
Q

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

A

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
19
Q

Diversity & Community Functioning

starfish

A

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

20
Q

Keystone Species: Summation

A

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

21
Q

Food chain

A

representation of feeding relationships within a community

Descriptive diagram of flow of energy from prey to predator

22
Q

Food web

A

Representation of complex interactions of predators and prey

Primary producers form base of the food web

23
Q

Food Webs and Productivity

Trophic Level determined by:

A

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

24
Q

types of Control of Primary Production

A

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

25
Q

Carpenter

A

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

26
Q

Carpenter and Kitchell

came up with what hypothesis

A

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

27
Q

top-down effects
largest in
impact less when

A

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
28
Q

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

A

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

29
Q

Niches and Diversity of Algae and Plants

-why is there coexistence?

A
  • 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.
30
Q

algal niches

A

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.
31
Q

Diversity & Primary Production

A

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

32
Q

Algal & Plant Diversity & Increased Nutrient Availability

-adding nutrients to water or soils ____ diversity and ____competition

A
  • 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
33
Q

Paradox of Enrichment

production and diversity are often ____ correlated

A

Diversity & Production often negatively Correlated

-Habitat Heterogeneity
Monocultures often most Productive
Dominant Species Extremely successful

34
Q

Disturbance

A

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

35
Q

Sousa defined disturbance:

A

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

36
Q

Disturbance and Diversity
white and Pickett
two major characteristics

A 
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
37
Q

Intermediate Disturbance Hypothesis

A

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.
38
Q

Dynamic Equilibrium Model

A

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

ecology exam 2 and 3 (10 decks)

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