chap. 4 key terms
Terms
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- equilibruim communities
- - a community subject to periodic disruptions, usually by fire, that prevent tit from reaching a climax stage.
- primary succession
- an ecological succession that begins in an area where no biotic community previously existed.
- territoriality
- an intense form of intraspecific competition in which organisms define an area surrounding their home site or nesting site and defend it against other species.
- fire-climax communities
- an equilibrium community maintained by periodic fires.
- mutualism
- a symbiotic relationship between individuals of two different species in which both species benefit from the association.
- edge effects
- a change in species composition, physical conditions, or other ecological factors at the boundary between two ecosystems.
- predator
- an organism that feeds directly on other organisms in order to survive.
- Mullerian mimicry
- Evolution of two species, both of which are unpalatable an, have poisonous stingers or some other defense mechanism, to resemble each other.
- pathogens
- an organism that produces disease in a host organism, disease being an alteration of one or more metabolic functions in response o the presence of the organism.
- natural selection
- the mechanism for evolutionary change in which environmental pressures cause certain genetic combinations in a population to become more abundant; genetic combinations best adapted for present environmental conditions tend to become predominant.
- environmental indicators
- organisms or physical factors that serve as a gauge for environmental changes.
- Batesian mimicry
- evolution by one species to resemble the coloration, body shape, or behavior of another species that is protected from predators by some sort of defensive mechanism.
- habitat
- the place or set of environmental conditions in which a particular organism lives.
- ecological development
- a gradual process of environmental modification by organisms.
- commensalism
- a symbiotic relationship in which one member is benefited and the second is neither harmed nor benefited.
- ecotones
- a boundary between two types of ecological communities.
- climax community
- a relatively stable, long-lasting community reached in a successional series; usually determined by climate and soil type.
- interspecific competition
- in a community, competition for resources between members of different species.
- coevolution
- the process in which species exert selective pressure on each other and gradually evolve new feature or behaviors as a result of those pressures.
- parasites
- an organism that lives in or on another organism, deriving nourishment at the expense of its host, usually without killing it.
- abundance
- the number or amount of something.
- pioneer species
- in primary succession on a terrestrial site, the plants, lichens, and microbes that first colonize the site.
- disclimax communities
- a community subject to periodic disruptions, usually by fire, that prevent it from reaching a climax stage.
- diversity
- the number of species present in a community as well as the relative abundance of each species.
- intraspecific competition
- in a community, competition for resources among members of the same species.
- primary productivity
- synthesis of organic materials by green plants using the energy captured in photosynthesis.
- secondary succession
- succession on a site where an existing community ahs been disrupted.
- resource partitioning
- in a biological community, various populations sharing environmental resources through specialization, thereby reducing direct competition.
- complexity
- the number of species at each trophic level and the number of trophic levels in a community.
- tolerance limits
- chemical or physical factors that limit the existence, growth, abundance, or distribution of an organism.
- plankton
- primarily microscopic organisms that occupy the upper water layers in both freshwater and marine ecosystems.
- evolution
- a theory that explains how random changes in genetic material and competition for scarce resources cause species to change gradually.
- keystone species
- a species whose impacts on its community or ecosystem are much larger and more influential than would be expected from mere abundance.
- symbiosis
- the intimate living together of members of two different species.
- ecological niche
- the functional role and position of a species within a community or ecosystem, inducing what resources it uses, how and when it uses the resources, and how it interacts with other populations.