Species
In biology, a species (plural: species) is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem. Differing measures are often used, such as similarity of DNA, morphology, or ecological niche. Presence of specific locally adapted traits may further subdivide species into "infraspecific taxa" such as subspecies (and in botany other taxa are used, such as varieties, subvarieties, and formae).
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Famous quotes containing the word species:
““If Steam has done nothing else, it has at least added a whole new Species to English Literature ... the booklets—the little thrilling romances, where the Murder comes at page fifteen, and the Wedding at page forty—surely they are due to Steam?”
“And when we travel by electricity—if I may venture to develop your theory—we shall have leaflets instead of booklets, and the Murder and the Wedding will come on the same page.””
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)
“The question that will decide our destiny is not whether we shall expand into space. It is: shall we be one species or a million? A million species will not exhaust the ecological niches that are awaiting the arrival of intelligence.”
—Freeman Dyson (b. 1923)
“Any reading not of a vicious species must be a good substitute for the amusements too apt to fill up the leisure of the labouring classes.”
—James Madison (1751–1836)