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what is competition?
A negative interaction between individuals for use of a resource
What is intraspecific competition?
competition btw/among orgaisms of the same species
What is interspecific competition?
Competition btw/among different species
What is amensalism
- An interaction where one species is affected negatively whereas the other species reamains unaffected.
- (penecillium bacteria)
An interaction where one species benefits whereas the remains unaffected
What is mutualism?
- An interaction between species that is beneficial to both.
- (miccorhizae and plants)
What is antagonism?
- Interaction where one species benefits and the other is negatively affected.
- (herbivory, predation, parasitism)
What are some examples of limiting resources?
Sunlight, H2O, space, food
What is exploitative competition?
- Indirect competition. One species denies another access to a resource simply by consuming it first.
- (ants and grasshoppers competing for grass)
What is interference competition?
- Direct competition. One species actively inhibits the foraging, reproduction or survival of another.
- (two male deer fighting for a mate)
What was Tansley's (1917) Common Garden Experiment?
Tested the reproductive abilities of two species of a plant on different types of soil. Found that each plant could out compete the the other on its preferred soil. (Home turf advantage)
What is competitive Exclusion?
G.F. Gause. When species are competing for the same resource, one species will dominate and out compete the other leading to the other's extinction. It is impossible for species of the same niche to coexist.
What is the per-capita rate of change equation?
- r=per-capita growth rate
- N=# individuals
- k=carrying capacity
What is the plankton paradox?
It flies in the face of the competitive exclusion principle. There are over 5000 species of plankton all coexisting onthe same few resources.
What is a niche?
A range of resources that a species can habitat or a range of conditions it can tolerate
How did Joseph Grinnel define the niche?
All of the habitat conditions that are required for a species to exist.
How did Charles Elton define the niche?
He focused on how species fit into the ecological community in which they occurred. He based the niche on the ecological role of an organism in a community especially in regard to food consumption.
How did G. Evelyn Hutchinson define the niche?
A mutidimensional hypervolume where many variables restrict the persistance of a species. Combined the fundamental (Grinnellian) and the realized (Eltonian) niches.
What is niche partitioning?
- The use of a limiting resource by different species in different ways reducing interspecific competition and allowing for coexistence.
- (dividing up the pie so everyone can have a piece)
What is niche overlap?
the extent to which two species require the same resource.
What is niche divergence?
Phenomenon associated with reduced interspecific competition.
What is a fundamental niche?
The total range of environmental conditions over which an organism can survive and reproduce. (abiotic)
What is the realized niche?
Actual conditions over which a species can survive and reproduce in nature. (biotic)
What is an autotroph?
An organism that assimilates engery from inorganic resources such as sunlight.
What is a heterotroph?
An organism that consumes energy-rich compounds made by autotrophs.
What are primary producers?
Autotrophs that convert inorganic resources to energy-rich resources.
What is the difference between a parasite and a parasitoid?
A parasite lets its host live where as a parasitoid eventually kills it.
What is the non-equilibrium theory?
an explanation for (usually local) species richness that requires fluctuatin conditions (eg. predation or temp) to keep dominant species from monopolizing resources.
What is the intermediate disturbance hypothesis?
Disturbance is needed to maintain species richness.
What happens at low disturbance, intermediate disturbance and high disturbance?
- low disturbance- competitive species dominates.
- intermediate disturbance-species richness is high
- high disturbance-most species can't survive
What is a disturbance?
Any event that removes biomass from a community resulting in decreased resource availability.
What is facilitation?
- A species interaction (usually following a disturbance) through which at least one species benefits and neither are harmed typically with regard to protection against the physical environment.
- (Coral and algae provide a place for plant seed to attach to and then grow)
What is a dominant species?
A species that has a large community-wide effect.
What is a foundation species?
- Type of dominant species that has a large effect on a community because of their abundance. They are usually sessile.
- (plants, muscles,mangroves,kelp, barnacles).
What is a keytone species?
- A type of dominant species that has a large effect on other species because of the 'role' they play.
- (predators or ecosystem engineers such as sea otters, starfish, beavers, prairie dogs, wolves)
What is an ecosystem engineer?
A species that changes the physical structure of habitat thereby creating opportunities for other organisms to grow and reproduce.
What is the Lottery Model (Sale 1977)?
Assumes that resources are captured at random by recruits from a larger pool of potential colonists. It is really relevant in areas with niche overlap.
What is the difference between deterministic and stochastic?
- Deterministic-arising from predictable, fixed factors.
- Stochastic-arising from random factors due to chance
What is an example of an indirect effect?
Wolves eat elk (negative effect on elk). Elk eat riparian vegetation (negative effect on vegetation). From this we can conclude that wolves have a positive effect on riparian vegetation.
What is an indirect affect?
The affect of one species on another routed through a third species.
How are species interactions measured?
- 1) Remove one species (the interactor)
- 2) Look at the effect step one had on one or more other species (the target)
- 3) calculate the per-capita interaction strength.-the effect that one individual of a species has on the # of individuals in another species using the per-capita interaction strength formula.
What is coevolution?
A pattern of evolution in which two interacting species reciprocally influence each others' adaptations over time.
What are the filters to community membership?
- 1) Is the species in the regional species pool? Can the individuals of the species of interest immigrate to the new community?
- 2) Given that they can immigrate to the new community, do the abiotic conditions allow for the species to persist?
- 3)Given that they can handle the abiotic conditions of the new community, is the species dependent on or restricted by certain species interactions (biotic interactions)?
What are some prey defenses?
- crypsis (camouflage)
- chemical defenses
- aposematism (warning coloration).
What are non-consumptive effects?
activity effected by presence or absence of a predator.
What is the Clemenstian View
- "Communities are superorganims"
- They are deterministic and predictable
- Communities change in discrete ways, ultimately converging into a stable climax community
- Analogous to growth/development of an individual
What is the Glasonian view?
- Communities change by a gradual change in species abundance along an environmental gradient.
- Transitions are difficult to detect
- individualistic concept-each species responds individualistically to the environment
What is an ecotone?
zone of overlap btw. communities that share a mixture of species.
What is the difference btw. a closed and an open community?
An open community is distribute randomly and does not have distinct ecotones. In a closed community, species are distributed over similar geographic ranges and have similar density peaks.
What is a "bottom up" approach?
Viewing the effects of abiotic factors or primary producers as having a great effect on a community.
What is a "top down" approach?
Viewing the effects of consumers in higher trophic levels or systems as having a great effect on a community
What is the Lotka Volterra predator model equation?
- α=predator attack rate
- c=efficiency with which food is converted to population growth
- d=per capita death rate of predator in absence of prey.
What is the Lotka-Volterra prey model equation?
r=per capita growth rate
What are the assumptions of the Lotka-Volterra predator/prey models?
- Closed system (one predator and one prey
- There is exponential growth of predators in absence of prey
- There is exponential growth of prey in absence of predators
- Ability to consume prey is independent of prey density
- Predators immediately convert prey to new predators
What are the predator/prey functional responses?
- type 1: density has no effect. Rate of consumption is proporitonal to prey density
- type 2: prey consumption decreases at high prey density
- type 3: predators become more efficient as prey become more common
What is succession?
Sequences of changes in a community initiated by some disturbance.
What is primary succession?
- Occurs after a major disturbance where all living organisms are wiped out.
- (Bear rock, lava flows, Krakatau)
What is secondary succession?
Occurs after a set back after a disturbance that does not completely wipe out the biota of a community.
What is pioneer species?
The first species to grow after a disturbance
What is a intermediate species?
The species that colonize an area after the pioneer species
What is a climax community?
The stable final community that develops from ecological succession.
How do early colonists change environmental conditions?
Through facilitation, inhibition, and torlerance
What is ecosystem ecology?
The study of processes that link the living (biotic) components to the non-living (abiotic) components.
What are the abiotic components of a n ecosystem?
sunlight, temperature, nutrients (such as CO2, O2, N, P) precipitation, water moisture, soil
What are the biotic components of an ecosystem?
primary producers, omnivores, herbivores, carnivores, detritovores
What are some common questions ecosystem ecologists address?
- How much energy is produced by photosynthesis?
- How much energy/materials flow through food chain?
- What controls decomposition or recycling rates of materials?
By what percent does energy decrease as it is transferred through trofic levels?
What are the most important elements in an ecosytem?
N, P, CO2 and O2
What is eutrophication?
Can take place in creeks when algae is oversupplied with nutrients with nitrogen and phosphorus. Humans play a big role in this (fertilizers, mining, etc...)
What major organisms dominated in the Paleozoic, the Mesozoic and the cenozoic eras?
- mesozoic-reptiles (dinosaurs)