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Background Extinction Rate

the number of species that would be expected to go die off over a periods of time without human influence

Biodiversity

the variety of life forms in an ecosystem

Bottleneck effect

when a species goes through an event suddenly and significantly reduces its population and thus genetic diversity

Disturbance

a temporary change in environmental conditions that causes a pronounced change in an ecosystem

Ecosystem diversity

the number of ecosystems in a certain area

Ecosystem engineers

any organism that creates, significantly modifies, maintains or destroys a habitat

Ecosystem services

the direct and indirect contributions of ecosystems to human well-being

Evolution

the change in the characteristics of a species over several generations and relies on the process of natural selection

Founder effect

the reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors

Fundamental niche

all the environmental conditions in which a species is able to live

Genetic Diversity

the total number of genetic characteristics in the genetic makeup of a species

Genetic drift

change in allele frequencies in a population from generation to generation that occurs due to chance events

Indicator species

an organism whose presence, absence or abundance reflects a specific environmental condition

Gene flow

transfer of genetic variation from one population to another

Intermediate disturbance hypotehsis

the idea that local species diversity is maximized when ecological disturbances neither too rare nor too frequent

Island Biogeography

the number of species on any island reflects a balance between the rate at which new species colonize it and the rate at which populations of established species become extinct

Keystone species

a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically

Lichen

a composite organism consisting of a fungus and an alga functioning in a symbiotic relationship

Mass extinction

the loss of a large number of species across the Earth over a "short" geological period of time

Natural selection

the process whereby organisms better adapted to their environment tend to survive and produce more offspring

Niche specialist

an organism that has strict diet and habitat requirements

Niche generalist

an organism that can eat a variety of foods and thrive in a range of habitats

Realized niche

the environmental conditions in which a species actually lives once factors like competition are taken into account

Resilience

the ability of an ecosystem to recover from a disturbance and return to its pre-disturbed state

Pioneer species

the species that first colonize new habitats created by distrubance

Resistance

the ability for an ecosystem to remain unchanged when being subjected to a disturbance

Speciation

the formation of new and distinct species in the course of evolution

Species

group of organisms in which any two individuals can produce fertile offspring

Species Evenness

the relative abundance of each species

Species Richness

the number of species in a given area

Succession

the gradual process by which ecosystems change and develop over time

Tolerance

the range of conditions that an organism can withstand