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General Concepts on the Evolutionary Biology of Parasites
Peter W. Price
Vol. 31, No. 2 (Jun., 1977), pp. 405-420
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2407761
Page Count: 16
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There are probably more species of parasite than all non-parasite species combined. In the British insect fauna only 3.9% are estimated to be predators, whereas 35.1% are parasitic on plants, and 37.0% are parasitic on animals. In a parasite food chain based on plants, trends are probably in the direction of i) smaller size, ii) shorter life cycles, iii) more specialized species (i.e., lower ranges of tolerance), iv) less predictable resources, v) greater population fluctuations, vi) more patchily distributed hosts, vii) greater isolation between populations, viii) higher evolutionary rates. Five concepts are generated to account for the extensive adaptive radiations seen among parasitic taxa: 1) Parasites are adapted to exploit small, discontinuous environments. 2) Parasites represent the extreme in the exploitation of coarse-grained environments. 3) Evolutionary rates and speciation rates are high. 4) Adaptive radiation is extensive and depends upon, a) the diversity of hosts being exploited, b) the size of the host target, c) the evolutionary time available, d) the selective pressure for coevolutionary modification and e) the mobility of hosts. 5) Types of speciation other than through geographic isolation are at least as important as allopatric speciation. Areas of emphasis for further study are discussed.
Evolution © 1977 Society for the Study of Evolution