Ecology Test #3

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Terms in this set (...)

Resource Limitation
Limitation of population growth by resource availability
Intraspecific Competition
Competition between individuals of the same species
Interspecific Competition
Competition between individuals of different species.
Resource Competition
Intraspecific or interspecific competition for limited resources, generally not involving direct antagonistic interactions between individuals
Self-thinning
Reduction in population density as a stand of plant increases in biomass, due to intraspecific competition
-3/2 self-thinning rule
A rule resulting from the observation that plotting the average weight of individual plants in a stand against density often produces a line with an average slope of approx. -3/2
Niche
The environmental factors that influence the growth, survival and reproduction of a species
Competitive exclusion principle
The principle that two species with identical niches cannot coexist indefinitely
Fundamental niche
The physical conditions under which a species might live, in the absence of interactions with other species
Realized niche
The actual niche of a species whose distribution is restricted by biotic interactions such as competition, predation, disease, and parasitism
Allopolploidy
A process of speciation initiated by hybridization of two different species
Fetch
The longest distance over which wind can blow across a body of water; directly related to the max size of waves that can be generated by wind
Competition coefficient
A coefficient expressing the magnitude of the negative effect of individuals of one species on individuals on individuals of a second species
Isoclines of zero population growth
lines, in the graphical representation of the Lotka-Volterra competition model, where population growth of the species in competition is zero
Granivore
An animal that feeds chiefly on seeds
Character displacement
Changes in the physical characteristics of a species' population as a consequence of natural selection for reduced interspecific competition
Allopatric
Describes the condition in which population or species have nonoverlapping geographic ranges
Sympatric
Describes the condition in which populations or species have overlapping geographic ranges
Denno and Roderick
Demonstrated that Spartina plants that were heavily populated by planthoppers exhibited reduced concentrations of protein, chlorophyll, and moisture
Principle of Superior Competitive Ability
Explains how introduced species are able to invade and out compete communities of indigenous species
Trenched plots in New Hampshire white pine forests
Trenched plots removed potential belowground competition for resources
Tilman and Cowan
Grew the grass Sorgastrum nutans and found that plants grown at a low density grew to a larger size than plants grown at a high density. Competition for nitrogen was more intense at higher plant densities. Increased nitrogen in higher plant densities also did not result in larger plants but did in low densities.
The Lotka-Volterra model
Predicts that one species will exclude the other when the isoclines do not cross
Intraspecific competition example
Planthoppers and aphids demonstrate this principle because of their habit of aggregating, rapid population growth and mobile nature of their food supply
Competitive exclusion theory
Gause's theory stats that two species with identical niches cannot coexist indefinitely
Galapagos finches
Niche defined by beak morphology
Nice of salt marsh grass
1. Magnitude of tidal fluctuations
2. Fetch
3. Latitude
Gause's Paramecium caudatum and P. Aurelia
Demonstrated that when grown alone the carrying capacity for each species was determined by intraspecific competition for food. When grown together P. Aurelia survived while P. caudatum declined. Competitive exclusion resulted from the competition for food.