|variation in traits such as body weight or height in which a series of types are distributed on a continuum, not grouped into discrete categories|
|any modern theory of evolution holding that species evolve by natural selection acting on genetic variation|
parasitism par·a·sit·ism (pār'ə-sĭ-tĭz'əm, -sī-)
A symbiotic relationship in which one species, the parasite, benefits at the expense of the other, the host.
|parasitism (pār'ə-sĭ-tĭz'əm) Pronunciation Key
A symbiotic relationship in which one organism (the parasite) benefits and the other (the host) is generally harmed. Parasites derive nutrition from their host and may also gain other benefits such as shelter and a habitat in which to grow and reproduce. See more at parasite. Compare amensalism, commensalism, mutualism.