PHENOTYPIG DIMORPHISM AND POPULATIONAL FITNESS IN PHLOX.

Abstract

Evolution is a process which yields population systems whose corporate genotype can adjust to and prevail over a defined range of environmental vicissitudes. Populations of most species differ in their ability to exploit current environments and adjust to environmental change and correlatively vary in their probability of survival and reproduction. Those which maximize this probability may be regarded as most adapted. Populations which contribute most offspring to species' gene pool of following generation relative to other populations may be regarded as most fit. The distinction between fitness and adaptedness recently has been expounded by Dobzhansky (1968). The definition of populational fitness presented here is based upon a permutation of Dobzhansky's view of Darwinian fitness which he characterizes as the average contribution which carriers of genotype, or of a class of genotypes, make to gene pool of following generation relative to contributions of other genotypes. Darwinian fitness is a relative term whereas adaptedness is an absolute term. This paper will deal with dimorphism and adaptedness in perennial herb Phlox pilosa L. We will consider adaptedness of pink and white corolla phases within natural populations of P. pilosa and compare adaptiveness of populations which differ in pink-white balance. Adaptedness will be considered in terms of ability to exploit a vital environmental resource, namely pollinators. The phase and population which