In biology, the term species refers to all organisms of the same kind that are potentially capable, under natural conditions, of breeding and producing fertile offspring. The members of a species living in a given area at the same time constitute a population. All the populations living and interacting within a particular geographic area make up a biological (or biotic) community. The living organisms in a community together with their non-living or abiotic environment make up an ecosystem. In theory, an ecosystem (and the biological community that forms its living component) can be as small as a few mosquito larvae living in a rain puddle or as large as prairie stretching across thousands of kilometers. A very large, general biotic community such as the Boreal Forest is called a biome. It often is difficult, however, to define where one community or ecosystem stops and another starts...