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Ecology

Field: Ecology

Sequence of Expressions

Two species competing for the same limited resource cannot coexist at constant population values; one will dominate and drive the other to extinction.
An organism's success is based on a complex set of conditions and that each organism has a certain minimum, maximum, and optimum environmental factor or combination of factors.
The number of species found on an undisturbed island is determined by immigration and extinction rates, which are influenced by the distance of the island from the mainland and the size of the island.
A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.
During the transfer of energy from organic food from one trophic level to the next, only about ten percent of the energy is stored as flesh.
Principle

Allee Effect

A correlation between population size or density and the mean individual fitness (often positive correlation) of a population or species.
Selection of combinations of traits in an organism that trade off between quantity and quality of offspring.
Hypothesis

Gaia Hypothesis

Living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.
Powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed.
A model for classifying and describing flowing water, in addition to the classification of individual sections of waters after the occurrence of indicator organisms.
The largest yield (or catch) that can be taken from a species' stock over an indefinite period.
A pair of first-order non-linear differential equations, frequently used to describe the dynamics of biological systems in which two species interact, one as a predator and the other as prey.
Specialized natural enemies such as herbivores and pathogens maintain high diversity in tropical forests by reducing the survival rates of seeds and seedlings located close to reproductive adults or in high density.