A process by which characteristics that make an individual better suited to its environment become more common in a species.
A behavior or physical characteristic that allows an organism to live successfully in its environment.
The role of an organism in its habitat, or how it makes its living.
The struggle between organisms to survive as they attempt to use the same limited resource.
An interaction in which one organism kills another for food.
The organism that does the killing in a predation interaction.
An organism that is killed and eaten by another organism.
A close relationship between two species that benefits at least one of the species.
A relationship between two species in which both species benefit.
A relationship between two species in which one species benefits and the other is neither helped nor harmed.
A relationship in which one organism lives on or in a host and harms it.
The organism that benefits by living on or in a host in a parasitism interaction.
The organism that a parasite lives in or on in a parasitism interaction.
The study of where organisms live.
The movement of organisms from one place to another.
The typical weather pattern in an area over a long period of time.
A group of land ecosystems with similar climates and organisms.
An area that receives less than 25 centimeters of precipitation per year.
An area populated by grasses and other nonwoody plants. Most grasslands get 25 to 75 centimeters of rain each year.
A grassland close to the equator that receives as much as 120 centimeters of rain per year.
A tree that sheds its leaves and grows new ones each year.
A tree that produces its seeds in cones and that has needle-shaped leaves.
An extremely cold, dry biome.
Soil that is frozen all year.