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Troublesome words


the process of an organism's adjustment to an abiotic factor


the study of geographic distribution of species.

Age structure

the relative amount of individuals in each age bracket (cohort) of a population

Life history

the traits that affect an organism's schedule of reproduction and survival


selection for life history traits that are sensitive to population density


have as many offspring as possible as fast as possible (fish, insects)

Opportunistic populations

show exponential growth and have small organisms with early maturation, short life span, and limited parental care to offspring

Intraspecific competition

competition between members of the same species

Ecological niche

A specific role of a species within an ecosystem, including its use of resources, and relationships with other species.

Fundamental niche

the full range of conditions that a species can tolerate and resources it can use

Resource partitioning

in a biological community various populations sharing environmental resources through specialization thereby reducing direct competition

Exotic species

organisms that are not native to a particular area

Mark-recapture method

A sampling technique used to estimate wildlife populations.

Species richness

the number of different species in a community

Species diversity

Number of different species in the biosphere, the number and relative abundance of species in a biological community


process by which two species evolve in response to changes in each other

Cryptic coloration

coloring that conceals or disguises an animal's shape


a defense in which one organism resembles another that is dangerous or poisonous

Batesian mimicry

A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators.

Mullerian mimicry

evolution of two species, both of which are unpalatable and, have poisonous stingers or some other defense mechanism, to resemble each other

Competitive exclusion principle

ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time


conversion of nitrates into nitrogen gas, process in which fixed nitrogen compounds are converted back into nitrogen gas and returned to the atmosphere

Primary productivity

rate at which organic matter is created by producers in an ecosystem

Gross primary productivity

the rate at which organic matter is assimilated by plants and other producers during a period of time over a certain area

Net primary productivity

The gross primary productivity minus the energy used by the producers for cellular respiration; represents the storage of chemical energy in an ecosystem available to consumers.


the total mass of living matter in a given unit area

Standing crop biomass

the weight or mass of above-ground, dry plant material in a defined area at a given point in time.

Limiting nutrient

single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem

Biomass pyramid

diagram representing the biomass in each trophic level of an ecosystem


the oxidation of ammonium compounds in dead organic material into nitrates and nitrites by soil bacteria (making nitrogen available to plants)


the formation of ammonia compounds in the soil by the action of bacteria on decaying matter

Biodiversity crisis

the current rapid decline in the variety of life on Earth, largely due to the effects of human culture

Endemic species

species that are native to and found only within a limited area

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