Ch. 8 Community Ecology
Published on Dec 05, 2015
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PRESENTATION OUTLINE
Vocabulary Words
Theory of island biogeography (species equilibrium model) - the number of species found on an island is determined by a balance between two factors: the immigration rate (of species new to the island) from other inhabited areas and the extinction rate (of species established on the island). 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 different species (species diversity)
Native species - species that normally live and thrive in a particular ecosystem Nonnative (invasive, alien) species - species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans
Keystone species - species that play roles affecting many other organisms in an ecosystem
Photo by Rennett Stowe
Interspecific competition - attempts by members of two or more species to use the same limited resources in an ecosystem
Resource partitioning - 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
Predation - situation in which an organism of one species (the predator) captures and feeds on parts or all of an organism of another species (the prey)
Photo by james_gordon_losangeles
Parasitism - occurs when one species feeds on another organism, living on or in the organism
Mutualism - types of species interaction in which both participating species generally benefit
Commensalism - 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
Ecological succession - 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
Photo by gbohne
Primary succession - ecological succession in a bare area that has never been occupied by a community of organisms
Secondary succession - ecological succession in which an area of natural vegetation has been destroyed, but the soil is not.
Pioneer species - first hardy species, often microbes, mosses, and lichens, that begin colonizing a site at the first stage of ecological succession
Early successional plant species - plant species found in the early stages of succession, can live under harsh conditions but has a short life span
Midsuccessional plant species - grasses and low shrubs that are less hardy than early successional plant species
Late successional plant species - mostly trees that can tolerate shade, fairly stable complex forest community
Photo by Darkroom Daze
Disturbance - an event that disturbs an ecosystem, natural (tornado, hurricane, etc) or human (deforestation, plowing) act
Complexity - 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
Precautionary principle - when there is scientific uncertainty about potentially serious harm from chemicals or technologies, decision makers should act to prevent harm to humans and the environment
Photo by AtmosNews - NCAR & UCAR
Main Points
One of the most important things about this chapter would be the structure and diversity of communities. For instance, there are different plant life, species and landscapes that all interact with each other in various ways. Each community can contain a wide array of species that play different ecological roles and are great indicators of the multitudes of changes occurring within that specific community. Along with great diversity, there are different food chains competing for survival. Furthermore, each food chain features predator/prey relationships, parasitic relationships between parasites and hosts, mutualistic relationships that benefit both organisms involved in the relationship, and commensalism, or a relationship among two organisms in which one organism is unaffected and the other organism benefits. Additionally, all of these factors contribute in helping or harming the stability and balance of an ecosystem. With that said, ecosystems change over time in order to adapt to new environmental conditions. Specifically, the gradual change in species composition of a given area is known as ecological succession.
Photo by Self-forming Streams
