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an interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree
competitive exclusion principle
no two species can occupy exactly the same fundamental niche indefinitely in a habitat where there is not enough of a particular resource to meet the needs of both species
in ecological terms, refers to the number of species in a community at each trophic level and the number of trophic levels in a community
a discrete event that disrupts an ecosystem or community. examples of natural disturbances include fires, hurricanes, tornadoes, droughts, and floods. examples of human-caused disturbances include deforestation, overgrazing, and plowing
early successional plant species
plant species found in the early stages of succession that grow close to the ground, can establish large populations quickly under harsh conditions, and have short lives
process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities
plant that uses its roots to attach itself to branches high in trees, especially in tropical forests
situation in which two competing species have equal access to a specific resource but differ in how quickly or efficiently they exploit it
breakup of a habitat into smaller pieces, usually as a result human activities
community at an early stage of ecological succession. it usually has a low number of species and ecological niches and cannot capture and use energy and cycle critical nutrients as efficiently as more complex, mature communities
species that serve as early warnings that a community or ecosystem is being degraded
situation in which one species limits access of another species to a resource, regardless of whether the resource is abundant or scarce
attempts by members of two or more species to use the same limited resources in an ecosystem
attempts by two or more organisms of a single species to use the same limited resources in an ecosystem
late successional plant species
mostly trees that can tolerate shade and form a fairly stable complex forest community
fairly stable, self-sustaining community in an advanced stage of ecological succession; usually has a diverse array of species and ecological niches; captures and uses energy and cycles critical chemicals more efficiently than simpler, immature communities
midsuccessional plant species
grasses and low shrubs that are less hardy than early successional plant species
species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans
animal that can use both plants and other animals as food sources. examples are pigs, rats, cockroaches, and people
consumer organism that lives on or in and feeds on a living plant or animal, known as the host, over an extended period of time. it draws nourishment from and gradually weakens its host; it may or may not kill the host
interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host
fist integrated set of plants, animals, and decomposers found in an area undergoing primary ecological succession
first hardy species, often microbes, mosses, and lichens, that begin colonizing a site as the first stage of ecological succession
situation in which an organism of one species captures and feeds on parts or all of an organism of another species
interaction between two organisms of different species in which one organism, called the predator, captures and feeds on parts or all of another organism
ecological succession in a bare area that has never been occupied by a community of organisms
ability of a living system to restore itself to original condition after being exposed to an outside disturbance that is not too drastic
process of dividing up resources in an ecosystem so that species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places
ecological succession in an area in which natural vegetation has been removed or destroyed but the soil is not destroyed
ability of a living system to withstand or recover from externally imposed changes or stresses
species interaction in which two kinds of organisms live together in an intimate association. members of the participating species may be harmed by, benefit from, or be unaffected by the interaction
process in which organisms patrol or mark an area around their home, nesting, or major feeding site and defend it against members or their own species
theory of island biogeography
the number of species found on an island is determined by a balance between two factors: the immigration rate from from other inhabited areas and the extinction rate. the model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of species differently
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