| A | B |
|---|
| biotic factor | biological influence on organisms within an ecosystem |
| abiotic factor | physical, or nonliving, factor that shapes an ecosystem |
| habitat | the area where an organism lives, including the biotic and abiotic factors that affect the organism |
| niche | full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions |
| resource | any necessity of life, such as water, nutrients, light food, or space |
| 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 |
| predation | interaction in which one organism captures and feed on another organism |
| symbiosis | relationship in which two species live closely together |
| mutualism | symbiotic relationship in which both species benefit from the relationship |
| commensalism | symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed |
| parasitism | symbiotic relationship in which one organism lives in or on another organism and harms it |
| host | the organism from which a parasite obtains all or part of its nutritional needs |
| ecological succession | gradual change in living communities that follow a disturbance |
| primary succession | succession that occurs on surfaces where no soil exists |
| pioneer species | first species to populate an area during primary succession |
| lichen | an organism that has a symbiotic relationship between a fungus and a green algae or a cyanobacteria |
| secondary succession | succession following a disturbance that destroys a community without destroying the soil |
