Ecology: Populations, Communities, and Ecosystems
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30 terms
Terms | Definitions |
|---|---|
 habitat | where the organisms lives |
| niche | how the organism uses it's environment (it's job); includes all factors the species needs to survive |
| competitive exclusion | one species per niche; if two species compete for the same niche, one will be pushed out |
| ecological equivalent | species that occupy similar niches in different regions |
| competition | two organisms fight for the same limited resources |
| interspecific competition | two different species compete for a resource |
| intraspecific competition | two members of the same species compete for a resource |
| predation | one organism captures and feeds on another organism |
| symbiosis | close relationship between two different species |
| mutualism | both organisms benefit |
| commensalism | one organism benefits, the other is neither helped nor harmed |
| parasitism | one organism benefits, the other is harmed |
| population density | the number of individuals of a population in a given area |
| population dispersion | how members of a population are grouped in an area; clumped, uniform, or random |
| survivorship curve | a diagram showing the number of surviving members over time from a measure set of births |
| Type I survivorship curve | low level of infant mortality and an older population (common in large mammals and humans) |
| Type II survivorship curve | survivorship is equal at all stages of life (common in birds and reptiles) |
| Type III survivorship curve | very high birth rate, very high infant mortality (common in invertebrates and plants) |
| Primary Succession | The development of an ecosystem in an area that was previously uninhabited (starts with bare rock and no soil) |
| Pioneer species | The first organisms that live in a previously uninhabited area (for example, lichens and mosses) |
| Secondary succession | the reestablishment of a damaged ecosystem in an area where soil was left intact. |
| Climax community | the stable biological community composed of species best adapted to average conditions in that area |
| Immigration | the movement of individuals into a population |
| Emigration | the movement of individuals out of a population |
| Exponential Growth | unlimited resources allow populations to grow without limits; "J" shaped curve |
| Logistical Growth | limited resources allow populations to grow to at an exponential rate until the resources become scarce and population growth levels off; "S" shaped curve |
| Carrying capacity | the maximum number of individuals a given environment can support |
| Population crash | a dramatic decline in the size of a population over a short period of time |
| Density Dependent Limiting Factor | limiting factor affected by the number of individuals in a given area; competition, predation; parasitism, disease |
| Density-Independent Limiting Factors | limiting factor that affects all populations regardless of density; unusual weather; natural disasters; human activity |
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