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:
“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)
“There are minds so impatient of inferiority that their gratitude is a species of revenge, and they return benefits, not because recompense is a pleasure, but because obligation is a pain.”
—Samuel Johnson (1709–1784)
“A man, to be greatly good, must imagine intensely and comprehensively; he must put himself in the place of another and of many others; the pains and pleasures of his species must become his own.”
—Percy Bysshe Shelley (1792–1822)