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:
“As kings are begotten and born like other men, it is to be presumed that they are of the human species; and perhaps, had they the same education, they might prove like other men. But, flattered from their cradles, their hearts are corrupted, and their heads are turned, so that they seem to be a species by themselves.... Flattery cannot be too strong for them; drunk with it from their infancy, like old drinkers, they require dreams.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“Books, gentlemen, are a species of men, and introduced to them you circulate in the “very best society” that this world can furnish, without the intolerable infliction of “dressing” to go into it. In your shabbiest coat and cosiest slippers you may socially chat even with the fastidious Earl of Chesterfield, and lounging under a tree enjoy the divinest intimacy with my late lord of Verulam.”
—Herman Melville (1819–1891)
“The principle of avoiding the unnecessary expenditure of energy has enabled the species to survive in a world full of stimuli; but it prevents the survival of the aristocracy.”
—Rebecca West (1892–1983)