Indicator species
From Wikipedia, the free encyclopedia
The term Indicator species applies to animals or plants that are in some way an indicator species of the environment. As such they define a trait, or characteristic of the environment. The two most common uses of the term indicator species are when a "Range" or "ecoregion" is delineated, or when an indicator of an environmental condition is met, (for example a species being affected by a disease outbreak/infestation). Pollution, diseases, species competition-(invasive species) and climate changes can be factors for these environmental changes.
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[edit] Indicator species of range
As an indicator species of a range, an environmental ecoregion is typically defined. The Lechuguilla is a cactus that regionally helps define the Chihuahuan Desert of Northern Mexico and the SW United States. In Central America, the Guatemalan magnolia elevationally defines the limits of the cloud forests of mountains.
For paleoclimates, an extant species may be an indicator of a former climate condition. The Discus macclintocki snail defines a former Ice sheet region of the northern Midwest US.
In some cases entire groups of fauna/flora may be an indicator of range. Invasive species that enter a continent or ecoregion advance at rates dependent upon environmental conditions, whether they are temperature, food supply, physical barriers, etc. An example may be observed by the spread of the Africanized bee as it enters southern North America.
[edit] Specialized use as indicator
Prospecting has been a minor use of an indicator species. Folklore may have led to recent attempts to utilize some species as an indicator to search out a specific natural resource-(even water). For finding uranium, botanical prospecting uses various plants, including Astragalus, Oenothera, and Desert trumpet.
[edit] Indicator species of environmental condition
Recent examples of North American species affected by environmental changes are the Gray Jay and the American Dipper. The American Dipper, a bird requiring the habitat of clear, mountainous streams can be displaced by siltation from land development, or land-wasting runoff, forest fire runoff, etc. The Gray Jay appears to have been affected by rising global warming temperatures that affect its food larder in southerly (warmer) portions of its range, and is less commonly found there.
Many indicator species of the ocean systems are fish, invertebrates, periphyton, macrophytes, and specific species of ocean birds (the Atlantic Puffin). Amphibians are also common indicator species, as they may have become repositories of bioindicator chemicals, or of ecological conditions relating to global warming, air pollution/chemicals, newly extant diseases (fungus), or environmental pressure on the ecosystem, which affect the population numbers, and the quality of the individuals.
