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Ecology 2 Midterm
Ecology
104
Biology
02/04/2013

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Term
Ecology
Definition
the study of the distribution and abundance of organisms and the factors and interactions that determine distribution and abundance
Term
Aristotle 350 BC
Definition
Historia Animalium: patterns of the natural world explained by natural causes
Term
Herodotus and Plato
Definition
Providential ecology: balance of nature
Term
Graunt 1662
Definition
father of demography: study of population growth
Term
Leeuwenhoek 1687
Definition
how populations grow over time
Term
Buffon 1756
Definition
how predators regulate prey population: population regulation
Term
Malthus 1798
Definition
used exponential growth to explain revolutions
Term
Quetelet 1835, Verhulst 1838
Definition
proposed and studied the idea of logistic population growth
Term
Verhulst 1838
Definition
logistics curve: population regulation
Term
Farr 1843
Farr's rule
Definition
Introduced a rule regarding the relationship between population size and the death rate: as density increases mortality increases.
Term
Edward Forbes 1887
HC Cowles 1899
Definition
community regulation and succession, mostly looked at patterns
Term
Robert Ross 1908
Definition
systems analysis
mathematical model of the spread of infectious disease (malaria)
Term
AG Tansley 1904
FE Clements 1905
Charles Elton 1927
Definition
some of the founders of modern ecology (experimental): why pattern occured
Term
Rachel Carson
Definition
helped make ecology accepted by the public- wrote Silent Spring, a work exposing the negative effects of pesticide use
Term
Abiotic components
Definition
non-living chemical and physical factors
Term
Biotic components
Definition
living factors
Term
Does ecology typically operate at the high of low scales of biological organization?
Definition
High scales
Term
Organism
Definition
a single individual or a single species
Term
Population
Definition
individuals of the same species living in the same geographical area
Term
Community
Definition
2 or more populations living in the same geographical area
Term
Ecosystem
Definition
comprising of the community and its physical environment
Term
Biosphere
Definition
lithosphere (rock), hydrosphere (water) and atmosphere (gas)
Term
Hypothesis Testing
Definition
p-values: measure the strength of conclusions being drawn
Null hypothesis: assume there is no association between variables
Significance testing: if P is less than 0.05, then the results are statistically significant
Term
If a species is in a certain area...
Definition
1. it evolved there
2. it evolved elsewhere and the dispersed to that area
Term
If a species is not found in a certain area...
Definition
1. it evolved elsewhere and never dispersed there
2. it was once present but no longer is there
Term
Biogeographic regions
Definition
Based on the taxonomic similarities of the organisms living there (6 major regions)
Boundaries are set where species composition changes dramatically over short distances
Term
Weather
Definition
the short term state of atmospheric conditions at a particular place and time
Term
Climate
Definition
the long term average atmospheric conditions found over time (temperature, wind velocity, precipitation)
Climate varies because of differences in the amount of solar energy (drives global atmospheric and oceanic circulation)
Large scale distribution patterns can be predicted from climate conditions
Term
Daily Temperature Cycle
Definition
rotation of Earth on its axis
24 hour cycle
Term
Seasonal Temperature Cycle
Definition
annual cycle- fixed axial tilt at 23.5 degrees
variation in sunlight intensity and day length give rise to seasonal variation in temperature in north and south hemispheres
Term
Why are the tropics hotter than temperate regions? (3)
Definition
1. solar radiation strikes at almost right angles near the equator but at acute angles near the poles
2. same amount of radiant heat is concentrated over a smaller area at the tropics
3. at poles solar radiation passes through a deep layer of atmosphere (reflection, absorption, scattering)
Term
Global Air Circulation Pattern (4)
Definition
1. Wet hot air: radiant heat above equator warms the air (low pressure) at equator- moist, hot air rises to cooler altitudes and rains (tropical rainforests)
2. Hot dry air: cool air descends at latitudes of about 30 degrees north and 30 degrees south and heats (deserts)
3. Wet cool air: air picks up moisture and rises at 60 degrees north and south and rains (temperature rainforests)
4. dry cool air: drier air descents in polar regions (cold dry polar deserts)
Term
What determines the distribution of biomes?
Definition
Climate
Term
What are terrestrial biomes based on?
Definition
The structure of their dominant vegetation.
In each terrestrial biome vegetation has similar traits, but may not be closely related- looks similar and functions in a similar way but species could be totally different
Term
What are aquatic biomes based on?
Definition
Their physical and chemical differences
Term
Transplant experiments
Definition
how to analyze a distribution on a smaller scale- see what factors are limiting the distribution.
move organism and see if it can survive and reproduce in a new environment- must go through at least one generation
Term
If a transplant is successful...
Definition
potential range of a species is larger than its actual range.
Lacks means of transport (dispersal)
Can move but chose not to (habitat selection)
Term
If a transplant is unsuccessful...
Definition
potential range of a species is the same as its actual range.
limits imposed by other species (predators, competitors, parasites, disease)
positive effects of interdependent species
or some other physical/chemical barrier (too hot, too cold, etc.)
Term
Factors Limiting Distribution:
Dispersal
Definition
the movement of organisms from one geographical location to another.
most organisms are mobile
geographical barriers are common in nature.
barrier to dispersal- breached by human introduction.
have to control for the experiemental factors
Term
Factors Limiting Distribution:
Habitat Selection
Definition
organisms can move but choose to not live in certain habitats.
distribution may be limited by the behavior of individuals in selecting their habitat
behaviorally constrained distribution
Term
Factors Limiting Distribution:
Competition
Definition
-,- interaction: both species in the interaction have negative consequences.
can occur between 2 or more organisms or species that exploit the same types of limited resources and live in the same geographical area
Interference competition: direct physical interaction over resources- large consequences
Exploitative competition: indirect interaction over resources
Term
Natural patterns indicating competition
Definition
1. When species B is absent, species A lives in a wider range of habitats- Competitive release
2. if competition is strong, the geographic ranges of the two competitors may not overlap but have sharp boundaries
Term
Factors Limiting Distribution:
Predation
Definition
+,- interaction
Predation can limit the distribution of organisms via:
1. direct consumption of the prey
2. behavioral modifications of prey in the presence of predators
Term
Factors Limiting Distribution:
Physical and Chemical
Definition
temperature and availability of water are the 2 major limiting factors to the distribution of life on earth.
organisms have upper and lower lethal limits to physical and chemical factors.
Solutions are acclimation (dealing with it short term) or adaptation (evolutionary changes).
Also light and soil structure limits distributions
Term
Photo period
Definition
light is important to the development and behavior of many plants and animals that are sensitive to this period- drives the distribution of plants and thus animals
Term
Soil structure as a limiting factor
Definition
the composition of substrate affects water chemistry of streams and rivers which influences the resident plants and animals

Ex: serpentine soil is high in nickel and magnesium- only Goldfield flowers can prosper because they use magnesium instead or calcium. Goldfield flowers can survive in other soils but they are poor competitors
Term
Chaparral
Definition
Our ecosystem in SB, fire may be unpredictable in the short term but predictable in the long term
so many plant communities have become adapted to fire and are dependent on fire to maintain them- ash is a major fertilizer, fire opens up space and light
Term
Factors Limiting Distribution:
Disturbance
Definition
fires, hurricanes, tornadoes, and volcanoes
Frequent disturbance: may be predictable and organisms may be evolutionarily adapted to the disturbance
Infrequent disturbance: may be unpredictable and organisms will not have acquired evolutionary adaptations to them- most damaging
Term
Factors Limiting Distribution:
pH and Salinity
Definition
affects the distribution of marine and freshwater organisms
Term
Factors Limiting Distribution:
Currents, Oxygen
Definition
many organisms dependent on wind and water currents to disperse their propagules or young
oxygen can limit the distribution or organisms in lakes
important in aquatic environments
Term
Characteristics of Populations
Definition
Natality, Mortality, Immigration, Emigration
Term
Density
Definition
the number of individuals per unit area (terrestrial) or volume (aquatic)
Term
How do you measure population density? (3)
Definition
1. Total counts (almost impossible)
2. Sub-sampling methods: sub sample population to estimate densities and total population size (big assumption)
3. Indirect Indicators: number of nests, fecal droppings, tracks, etc. as estimates of density
Term
Patterns of Dispersion (3)
Definition
1. Clumped: most common, due to unequal distribution of resources and/or social behavior
2. Uniform: distributed based on minimum distance between indiv., due to interactions between individuals
3. Random: (least common) distributed without regard to position of other individuals
Term
Are emigration and immigration more important to small or large spatial/temporal scales?
Definition
The smaller the spatial/temporal scale, the greater the importance of movement to population dynamics
Term
Methods used to identify how population size changes (3)
Definition
1. Direct observations: not practical due to long lived organisms
2. View age structures:
- Type 1: humans, live for a long time and then die
-Type 2: birds, die at same percent per unit time
-Type 3: plants and fish, when you are born you have a high chance of death but then live for a very long time
3. Mathematical models
Term
Carrying Capacity (K)
Definition
maximum population size that an environment can support
population growth slows as its density approaches
Term
Why does the logistic curve not fit well for most natural population growth patterns? (name assumptions, 3)
Definition
1. Each individual added to the population has the same negative effect on population growth- less resources (exceptions: isolated plants and flamingos)
2. Population approaches K smoothly: lag time causes the population to overshoot and undershoot, oscillate about K
3. populations are large and density is important in regulation
Term
Density Dependent Control
(limiting factor)
Definition
factors that alter per capita birth or death rates in a population are dependent on population density (can stabilize population density)
-as density goes up, higher death rate
-bubonic plague and fleas: spread disease because they kept biting
-resources
-competition predation
Term
Density Independent Control (limiting factor)
Definition
factors that alter per capita birth or death rates in a population are independent of population density (do not stabilize population density) -percent death does not change no matter what the population density is -monarch butterfly- freeze wiped them out, didn't matter how many there were -usually weather and disturbances
Term
Are short term fluctuations in populations due to density dependent or density independent factors?
Definition
density- independent factors
Term
Stable Equilibrium
Definition
if perturbed population will return to initial density stabilizing forces dampen population fluctuation density dependent controls birth= death
Term
Unstable Equilibrium
Definition
if perturbed, population may not return to initial density destabilizing forces enhance population fluctuations inverse density dependence- density dependence with long time lags
Term
Metapopulations
Definition
populations is divided into discrete sub-populations connected by immigration and emigration
fast increase in migration: local population fluctuations are damaged
migration decrease: local population fluctuations are enhanced but there is an increased probability of extinction
intermediate migration: how most of the world works: shifting mosaic or occupied and unoccupied patches
Term
Mutualism
Definition
+,+ both species benefit from the association
ex: large African mammals and tick birds
Term
Commemsalism
Definition
+,0 one species benefits from the association, the other is unaffected (it doesn't affect the population)
ex: remora and shark
Term
Amensalism
Definition
-,0 one is unaffected and one has a negative affect
ex: walnut tree shading smaller trees
Term
What are the possible outcomes of competition? (3)
Definition
1. both species coexist
2. species 1 becomes extinct
3. species 2 becomes extinct
Term
Competitive Exclusion Principle (Gause Hypothesis)
Definition
No two species can occupy the same ecological niche simultaneously (complete competitors cannot exist)
Term
Niche
Definition
the biological role of an organism within the environment, where the organism fits in to
Term
Fundamental Niche (n dimensional hypervolume)
Definition
the multitude of conditions in which an organism can survive and multiply- the space you can potentially occupy
Term
Realized Niche
Definition
where an organism actually exists due to ecological constraints
Term
Where does competitive exclusion not occur? (3)
Definition
1. Unstable environments: never reach equilibrium, low density of organisms- population sizes aren't big enough to dominate resources
2. Environments in which species do not compete (unlimited resources or partitioning- giraffes eat higher up, zebras in the middle)
3. Fluctuating environments that reverse the direction of competition before extinction occurs- system changes so competitors never become too successful
Term
Five types of predation 
Definition

Carnivory

Parasitism

parasitoids

cannibalism

herbivory

Term
Lotka-Volterra Predator Prey Model Assumptions (2)
Definition

1. In the absence of predators, prey populations grow exponentially- assume unlimited resources

2. In the absence of food, predator populations decline exponentially 

 

These predator prey populations oscillate, but few good examples in natural populations

Term
How do prey persist? (3)
Definition

1. prey have a spatial (hiding) or temporal (eating at different times) refuge

2. optimal foraging: predators switch to other prey as original prey species fall to low abundance

3. antipredator strategies:

-chemical defense: aposematic coloration (to warn) and poison

-camouflage: cryptic coloration and mimicry

-displays of intimidation and fighting

-agility

-armor

-altered reproductive patterns: masting, so many offspring you overwhelm predator 

Term
Individualistic Hypothesis
Definition

Gleason

communities are chance assemblages of species with similar abiolic requirements

 

a more general way to say nonequilibrium view

Term
Interactive hypothesis 
Definition

Clements

communities are assemblages of dependent closely linked species 

 

a general way to say equilibrium view 

Term
Features of ecosystems (3)
Definition

1. open biological systems

2. one way flow of energy

3. cycling of nutrients: energy imput from the sun is made into nutrients

Term
Trophic Levels (5)
Definition

group species by functional similarity

defined by the number of steps through which energy passes to reach the organisms in it

1. primary producers

2. primary consumers: herbivores, decomposers, detritivores (eat primary producers)

3.secondary consumers (eat primary consumers)

4. tertiary consumers (eat secondary consumers)

5. quarternary consumers (eat tertiary consumers)

 

forms a hierarchy of feeding relationships- shows flow of energy through ecosystem

most communities only have 3-5 trophic levels 

Term
Biomass
Definition
measure of weight of dry tissue (carbon) an organism contains
Term
An average of ___ % of energy is transferred from one level to the next
Definition
10
Term
Top-Down Effects
Definition
the abundance of lower trophic levels depends on the effects of consumers from higher trophic levels
Term
Bottom Up Effects 
Definition
the abundance of higher trophic levels depends on factors such as nutrients and prey availability from lower trophic levels 
Term

Odd number of trophic levels means...

 

Even number of  trophic levels means...

Definition

odd- resources limitation

 

even- consumer limitation 

 

 

Term
Species diversity
Definition
species richness + species evenness 
Term
Species richess 
Definition
the number of species in a community
Term
Species evenness
Definition
the relative abundance of a species in a community
Term
Does more diversity mean more or less stability?
Definition
More stability
Term
Disturbance
Definition

an event that removes organisms and alters resource availability

 

communities with very high or low disturbance have lower species diversity than communities with moderate disturbance

Term
Intermediate disturbance hypothesis 
Definition

1. when disturbance is severe and frequent community is composed of good colonizers (r-selected) with high reproductive rates

2. when disturbance is mild and rare community is composed of good competitors (k-selectors)

 

Species diversity is highest where disturbance is moderate (intermediate) in severity and frequency- allows both colonizers (r) and competitors to coexist (k)

Term
The Diversity-Stability Hypothesis
Definition

1. disturbance in diverse communities is dampened by large numbers of interacting species 

2. the effect of disturbance is less than it would be in a species poor communities 

 

Higher diversity increases community stability 

Term
Succession 
Definition

Transition in species composition over time 

Primary succession: bare soil, no organisms

Secondary succession: soil, some organisms

Term
Successional pathway (2)
Definition

1. Early successional communities (r-selection): good dispersers (colonizers) and high reproductive rates

2. Late successional communities (k-selection): good competitors, exist near carrying capacity

Term
Successional patterns (2)
Definition

1. Directional succession: progressive change in species composition 

2. cyclical succession: change in species composition in which the original community is ultimately restored 

Term
Biological invasion and impacts
Definition

Invasive species: species that disrupt communities by a dominant colonization of a particular habitat or from loss of natural controls (predators or herbivors)

 

Impacts: changes in ecosystem structure and function

 

Environmental disturbance promotes biological invasion which can alter native succession and promote more invasion

Term
Niche relationships
Definition

the wider the average niche breadth the fewer the number of species in the community (extinction via competitive exclusion)

 

the narrower the average niche breadth the more species in the community (coexistence via resource partioning)

Term
How can predation increase richness? 
Definition

Predation may increase richness by allowing compeitively inferior species to coexist with superior competitors 

 

Term
Keystone species 
Definition

a species influence on the community is greater than would be expected on the basis of abundance 

 

moderate levels of predation increase species diversity

Term
Equilibrium model of island biogeography 
Definition

species richness is positively correlated with island size and negatively correlated with distance from the mainland 

 

if extinction is greater than immigration then species diversity decrease

if extinction is less than immigration then species diversity increases

Term
Equilibrium View (3)
Definition

1. communities are structured by biotic interactions (competition, predation, herbivory)

2. communities display global stability

3. niche diversification determines species diversity

 

interactive hypothesis

Term
Non-Equilibrium View (3)
Definition

1. communities composition is always changing and never in balance

2. no global stability

3. communities are patchworks of disturbance. Colonization and dispersal determine species diversity 

 

individual hypothesis 

Term
Biodiversity (3 levels)
Definition

1. genetic diversity (amount of genetic variation among species)

2. species diversity (number and relative abundance of species)

3. ecosystem diversity (diversity of structure and function in an ecosystem)

 

Conserve biodiversity because of economic value, ecosystem services, and environmental ethics 

Term
Inverse Density Dependence 
Definition

each individual added actually increases the population 

 

trees: more of them, work together to bring up the water

flamingos