ABSTRACT
Most books on evolution, even those which deal with evolutionary mechanics, emphasize the development of somatic traits. These are then discussed as adaptive units which can be measured in terms of selective coefficients. This method of explanation is derived from experiments and field observations which, for the sake of simplicity, are designed to test hypotheses linking traits to environmental parameters. The traits chosen are usually unambiguous units which can be catalogued in terms of specific physical characteristics. Nonetheless, extrapolation from these experiments to theory represents a somewhat artificial approach, since no trait has an adaptive value except in reference to some other traits of the system under discussion. The problem is handled statistically. Adaptation is measured in terms of the mean survival value of a gene: differences among organisms carrying the gene are “randomized out”—that is, the selection coefficient reflects the average value of the gene on all backgrounds.
