Ecology Exam One

If the richness of community "A" is lower than that of community "B", then

"A" has fewer species than "B"

If the evenness of community "A" is higher than that of community "B", then

"A" has more species than "B".

Ecology was derived from Greek words Oikos and Logos and means...

"Oikos"="house", "Logos"="the study of"

Frequency (F)

% of samples in which a species occurs How common?

Species Diversity

A combination of the number of species and their relative abundance

All the animals in the Lick Creek Park collectively is considered _______.

A community

All the plants (trees, shrubs and grasses) at the Lick Creak bottom collectively is considered ______.

A community

Which of the following is/are of the individualistic concept of community? a. species respond independently to environment b. no obligatory association of species c. communities vary continuously in space

All of the above

Why is species richness generally low in communities that experience high disturbance frequency, intensity, or both?

Because only highly disturbance-tolerant species can persist.

In a study conducted by Matthew Liebold and colleagues, the abundance of zooplankton was positively correlated with the abundance of phytoplankton across a large number of natural lakes, indicating __________ control by primary production of the abundance of organisms feeding at higher trophic levels in aquatic systems.

Bottom-up

Holistic Concept (F.E. Clements) "Interdependent communities"

Communities are highly organized by previous evolution and current interactions -distinct, interdependent association of species -discrete assemblages of organisms -superorganism

How are communities organized?

Communities are organized into food webs.

How do communities respond to disturbance?

Communities respond to disturbances with resistance, resilience, or switching among alternative stable states.

Why are transient climaxes not stable?

Frequent disturbances

In a ________________, you would plot abundances/IV of species along environmental gradients.

Gradient analysis

What concept of community organization suggests that a community is much more than the sum of its individual parts?

Holistic concept

The word "ecology" is derived from the Greek oikos, which means: __________.

House

What are the assumptions when using a chronosequence to document the pathway of succession? I. Various sites have similar abiotic conditions. II. The sites did not experience any disturbances. III. The sites pass through the same stages of growth.

I and III only

Importance Value (IV)

IV = (relative D + relative B + relative F) / 3 where (relative D) = D / (sum of D's of all species), etc. How important overall?

What happens to producer abundance when the top predator is removed in a food chain with three trophic levels and in a food chain with four trophic levels?

In three-level food chains, producer abundance will decrease, whereas in four-level food chains, producer abundance will increase.

What did Robert Whittaker's data on plant species composition along gradients of temperature and moisture in mountains show?

It provided evidence that challenged the concept of interdependent communities.

How might the carrying capacity for humans on Earth change if the human population ate mostly plant products instead of animal products?

It would increase the carrying capacity by over 50 percent.

Patterns of species abundance

Log-normal distribution or normal distribution

Which would be a characteristic of an early-succession species? large seed size, high root to shoot ratio, low shade tolerance, or slow growth rate

Low shade tolerance

At what frequency of disturbance would the most diversity be expected?

Medium frequency

Aquatic systems are often categorized by __________ __________ or by dominant _________.

Physical characteristics (e.g., stream or lake communities); organisms (e.g., coral reef communities)

Community

Populations of DIFFERENT species living together in a particular area Structure and Function; Interactions among populations

How do bottom-up effects typically affect the abundance of adjacent trophic levels in food chains?

Producers increase, herbivores increase, and predators increase.

Components of diversity

Richness and Evenness

Why might assimilation efficiencies be much higher for herbivores eating seeds than for herbivores eating leaves?

Seeds are easier to digest

A community contains five species (A, B, C, D, and E), and researchers remove species C. As a result, species B drives species A and D to extinction, but has no effect on the abundance of species E. Which of the five species is most likely to be a keystone species?

Species C

What affects species diversity?

Species diversity is affected by resources, habitat diversity, keystone species, and disturbance.

Why does an increase in total resources or number of added resources commonly lead to declines in species diversity?

Species diversity is usually highest at intermediate values of resources.

When you plot species relative abundance (y-axis) as a function of the rank order of the abundance of each species (x-axis), what does a line with a steep negative slope tell you?

Species evenness in the community is low.

How would a trade-off between dispersal ability and competitive ability affect where a species can effectively colonize?

Species with high dispersal ability and low competitive ability are better able to colonize large gaps in a community.

What is the difference in the classic and modern explanations for the succession of ponds and lakes?

Succession in the modern model is attributed to periods of extended drought.

The focus of ecological study at the organism/individual level is ___________.

Survival and reproduction

What does it mean when a community is said to exhibit top-down control?

The abundance of trophic groups is determined by the presence of predators.

Given that the distributions of many animals are determined by the species composition of the plant community, what might you predict about the diversity of animals in an ecotone with a more diverse ecosystem on one side and a less diverse ecosystem on the other side?

The amount of diversity would be higher than either ecosystem.

Why should we not expect a single climax community within a biome?

The composition of the climax community can vary with small environmental changes.

How do changes in stoichiometry affect assimilation efficiencies?

The efficiency of a consumer with a different nutrient ratio than its food is reduced.

If two plant species have similar dispersal and competitive abilities, what factor might help determine which species occupies an early seral stage?

The priority effect

Why are residence times much longer in forest ecosystems than in aquatic phytoplankton-based ecosystems?

The rate of consumption from the next trophic level in forests is lower.

What are the differences between the interdependent community and independent community perspectives of Frederic Clements and Henry Gleason?

The species in interdependent communities all rely on each other for survival; species in independent communities do not rely on each other for survival.

Which factor has a neutral effect on species interactions in succession? facilitation, the priority effect, inhibition, or tolerance

Tolerance

In a study, Matthew Leibold and colleagues added predatory fish to experimental lakes. When fish were added, the abundance of zooplankton decreased, and the abundance of phytoplankton increased, indicating __________ control by predators of the abundance of organisms feeding at lower trophic levels in aquatic systems.

Top-down

Richness

Total number of species (variety)

If humans cause a decrease in the abundance of sharks by overhunting fish such as tuna, it is an example of

a density-mediated indirect effect.

When discussing trophic levels a guild is

a group of species that feed on similar items.

Log-normal distribution

a normal, or bell-shaped, distribution that uses a logarithmic scale on the x-axis. In a typical community, only a few species have low or high abundance; most species have intermediate abundance; they follow a log-normal distribution. Log(base2)N=2^N

The difference between log-normal abundance distributions and rank-abundance curves is

a rank-abundance curve orders species by abundance; a log-normal distribution groups similarly abundant species together.

Ecotone

a transition zone from one community to another community. -Support a large number of species, including those from adjoining communities, and species specifically adapted to the ecotone

Which is NOT a factor that limits the net primary productivity of aquatic ecosystems? a. temperature b. phosphorus c. iron d. light

a. Temperature

Which process is used to measure primary productivity in aquatic ecosystems? a. measuring O2 uptake and release b. measuring CO2 uptake and release c. measuring changes in biomass d. measuring solar energy absorption

a. measuring O2 uptake and release

Edge vs. Ecotone

abrupt vs. more gradual transition (but is a function of scale; for example a beetle's perspective versus a humans)

Biosphere

all the living material and their environment on the EARTH Structure and Function: Global Processes

Dominance (B)

amount in bulk or weight (biomass, canopy cover, basal cover etc.) of a species per unit area How much?

Organism

any form of life; a living individual Structure and Function: Survival and reproduction; the unit of natural selection

Usually, the highest diversity is maintained

at intermediate level of disturbance.

Following are the relative abundance of 5 species in four hypothetical communities (A-D). Which community has the LOWEST diversity measured by Shannon-Wiener index? a. 0.25 0.25 0.25 0.25 0.00 b. 0.50 0.50 0.00 0.00 0.00 c. 0.21 0.21 0.21 0.21 0.16 d. 0.24 0.24 0.24 0.24 0.04

b. 0.50 0.50 0.00 0.00 0.00

Why do aquatic and terrestrial ecosystems differ in their pyramids of biomass?

because of the higher rates of consumption in aquatic biomes

Following are the relative abundance of 5 species in four hypothetical communities (A, B, C and D). Which community has the SECOND LOWEST diversity measured by Simpson's index? a. 0.21 0.21 0.20 0.19 0.19 b. 0.24 0.23 0.25 0.24 0.04 c. 0.25 0.26 0.24 0.25 0.00 d. 0.50 0.30 0.20 0.00 0.00

c. 0.25 0.26 0.24 0.25 0.00

Which does NOT reduce the efficiency of energy transfer between two trophic levels? a. the process of consumption b. the process of assimilation c. the number of trophic levels d. the amount of respiration

c. the number of trophic levels

System

collection of two or more interactive parts

Ecosystem

communities and their ABIOTIC environment in a particular space Structure and Function: Energy flux and cycling of nutrients

Individualistic Concept (H.A. Gleason) "Independent communities"

communities vary continuously in space along environmental gradient -individual species respond independently to environmental conditions -no obligatory association of species

Which is NOT a factor that limits the net primary productivity of terrestrial ecosystems? a. precipitation b. temperature c. nitrogen d. silicon

d. Silicon

Communities can have ________ or ________ boundaries.

distinct; gradual

Evenness

distribution of dominance (equitability)

Terrestrial communities are often categorized by their ___________ ______ species

dominant plant Examples: Beech-maple forest communities of Ontario; sagebrush communities of Wyoming.

Secondary succession occurs

in a habitat that has organic soil but no plants.

Trait-mediated indirect effects

include effects caused by changes in the distribution or behavior of an intermediate species.

When a community experiences succession, which is a common pattern of change in species richness?

increase, plateau, decline

What is the hierarchy of ecological systems?

individual, population, community, ecosystem, landscape, biome, biosphere

What concept of community organization suggests that a community is merely a fortuitous association of species whose adaptations and requirements enable them to live together under the physical and biological conditions of a particular place?

individualistic concept

Population

individuals of the SAME species living in a particular area Structure and Function: Population dynamics; the unit of evolution

Species

individuals that are capable of INTERBREEDING or share genetic similarity (taxonomic)

A keystone species is distinguished by

its disproportionately large effect on the community relative to its abundance.

An animal ecologist interested in gradient analysis would:

measure the abundance of animal species and physical conditions at a number of locations and then plot the abundance of each species as a function of one or more physical conditions.

Landscape

mosaic of ecosystems

Emergent properties

new properties emerging from the interactive combination of parts *The whole is greater than the sum of the parts

Density (D)

number of individuals of a species per unit area How many?

The diversity of a community incorporates both the ________ and _______ _________ of species.

number; relative abundance

Gradient Analysis

plotting abundances of species along environmental gradients (Line transect method)

The highest number of plant species in a landscape often occur in ecotones because

species that live on either side of the ecotone spread into it.

System hierarchy

systems within a system *Each Level [of complexity] finds its explanations for mechanism in the levels below, and its significance in the levels above

The number of individuals of a species per unit area is

the density of the species

The amount of bulk or weight (biomass, canopy cover, basal cover) of a species per unit area is

the dominance of the species.

The difference between gross primary productivity and net primary productivity is due to

the energy lost to respiration

Species richness is

the number of species in a community.

Habitat

the place, or physical and biological setting, where an organism lives

Niche

the range of abiotic and biotic conditions an organism can tolerate *No two species have the same niche!*

Ecology

the scientific study of INTERACTIONS among organisms and their environment.

Biome

very large ecosystems of SUBCONTINENTAL dimensions and strong biotic continuity

Predation

when an organism kills and consumes an individual Ex. Mountain Lion

Herbivory

when one organism consumes producers Ex. Bison

Parasitism

when one organisms lives in or on another organism Ex. Winter Tick

Competition

when two organisms that depend on the same resource have a negative effect on each other

Mutualism

when two species benefit from each other

Commensalism

when two species live in close association and one receives a benefit, whereas the other is unaffected