View Resource

Return to search results   |   Browse resources
Allomeric Variation. 1. The Theory and Some Consequences

abstract1 (full description below): The American Naturalist, Vol. 120, No. 6. (Dec., 1982), pp. 751-764.
Allomeric Variation. PDF/Acrobat file     SoulĂ©, M. E.

There is no general theory of morphological variation. Instead there is a collection of hypotheses which have been generated in disciplines (ecological genetics, quantitative genetics, population phenetics) which use different vocabularies and emphasize different problems. There is also a lot of undigested phenomenology. Such theoretical messiness is not surprising since the regulatory phenomena behind morphogenesis are among the most complex of biological processes. Nevertheless, just as genetics was a vigorous field before anyone knew about DNA, so we may still be able to reach some general, quasimechanistic syntheses about morphological variation in the period prior to the solution of the "development problem." This paper is an attempt to draw together several observations and ideas and to produce a coherent, though limited, theory of variation of morphometric characteristics, traits, that is, that are described by linear or volumetric measurements (in contrast to pattern or shape characteristics). For the sake of convenience, variation in morphometric traits can be examined at four levels. These are (1) within individual variation, such as bilateral asymmetry or segmental variation; (2) between individual variation such as is estimated by the variance or coefficient of variation of a trait in a population; (3) between trait variation, i.e., the differences in variability between different traits within a population or species; and (4) variation differences between populations; for example, population A of a species may be more variable for a certain set of traits than population B. These "levels" of variation, while arbitrary from the point of view of the source of variation (e.g., genetic or environmental), are very useful conceptually, and must not be confused.