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:
“Heaven and hell suppose two distinct species of men, the good and the bad. But the greatest part of mankind float betwixt vice and virtue.”
—David Hume (1711–1776)
“Nature seemed to have adorned herself for our departure with a profusion of fringes and curls, mingled with the bright tints of flowers, reflected in the water. But we missed the white water-lily, which is the queen of river flowers, its reign being over for this season.... Many of this species inhabit our Concord water.”
—Henry David Thoreau (1817–1862)
“Single-mindedness is all very well in cows or baboons; in an animal claiming to belong to the same species as Shakespeare it is simply disgraceful.”
—Aldous Huxley (1894–1963)