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The Evolution of Ecological Units above the Population Level

James W. Valentine
Journal of Paleontology
Vol. 42, No. 2 (Mar., 1968), pp. 253-267
Stable URL: http://www.jstor.org/stable/1302213
Page Count: 15
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The Evolution of Ecological Units above the Population Level
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Abstract

Ecological systems are organized as a hierarchy. Underlying the ecologic hierarchy is a genetic hierarchy that is ultimately based on nucleotides which are organized into units of heredity. From these units the ecological hierarchy proceeds to levels that include the individual organism, the niche (the functional aspect of the population), the ecosystem (the functional aspect of the community), the "biome" (the functional aspect of the province), and the biosphere (the functional aspect of the total planetary biota). Each level can be considered as a system of which the units of the preceding level form parts. Such systems can be described nearly independently and, when this is done, their internal processes display a progression of dynamic frequencies from high at the smallest level to low at the most inclusive level. Each of these systems may evolve by means of changes in the relations among its largest subsystems. Evolution of the more inclusive levels, however, includes changes in the relations among the subsystems of all the lower levels as well. Thus, some information about the most inclusive level may be gained from studying the least inclusive. Most paleontological information about the larger systems is based on data from the lower (population) level and not from intermediate levels. The entire hierarchy, however, evolves in concert, and study of the more inclusive systems may shed light upon pathways of evolution of the less inclusive.

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