Term | Definition |
habitat | the place where an organism usually lives |
ecological niche | all of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce in an ecosystem |
competitive exclusion | the exclusion of one species by another due to competition |
ecological equivalent | organisms that share a similar niche but live in different geographical regions |
competition | ecological relationship in which two organisms attempt to obtain the same resource |
predation | an interaction between two organisms in which one organism, the predator, kills and feeds on the other organism, the prey |
symbiosis | a relationship in which two different organisms live in close association with each other |
mutualism | a relationship between two species in which both species benefit |
commensalism | a relationship between two organisms in which one organism benefits and the other is unaffected |
parasitism | a relationship between two species in which one species, the parasite, benefits from the other species, the host, which is harmed |
population density | measure of individuals living in a defined area |
population dispersion | way in which individuals of a population are spread out over an area or volume |
survivorship curve | graph showing the surviving members of each age group of a population over time |
immigration | the movement of an individual or a group to a new community or region |
emigration | the movement of an individual or group out of its native area |
exponential growth | logarithmic growth, or growth in which numbers increase by a certain factor in each successive time period |
logistic growth | population growth that starts with a minimum numbers of individuals and reaches a maximum depending on the carrying capacity of the region; described by an S-shaped curve |
carrying capacity | the largest population that an environment can support at any given time |
population crash | dramatic decline in the size of a population over a short period of time |
limiting factor | environmental factor that limits the growth and size of a population |
density-dependent limiting factor | environmental resistance that affects a population that has become overly crowded |
density-independent limiting factor | environmental resistance that affects a population regardless of population density |
succession | the replacement of one type of community by another at a single location over a period of time |
primary succession | establishment and development of an ecosystem in an area that was previously uninhabited |
pioneer species | a species that colonizes an uninhabited area and that starts an ecological cycle in which many other species become established |
secondary succession | reestablishment of a damaged ecosystem in an area where the soil was left intact |