Phenotypic variation in Fucus spiralis (Phaeophyceae): morphology, chemical phenotype and their relationship to the environment

Phenotypic Variation of Fucus spiralis was examined in terms of morphology and chemical composition, as determined by pyrolysis mass spectrometry (PyM S). After discriminant analysis both techniques revealed the existence of t wo morphotypes which were subsequently designated as F. spiralis and F. spi ralis forma nanus. The nanus plants differed from the nominate spiralis in that they were shorter, narrower and had fewer branches, but had more units of growth from a single holdfast. F, spiralis f. nanus was consistently hi gher on the shore than F, spiralis, but the two morphotypes overlapped in t erms of shore exposure level. We suggest that the formae exist within a mos aic of stable phenotypes representing populations specifically adapted to t he local environment. PyMS data were in agreement with morphological descri ptions showing that gross morphology can be correlated with chemical compos ition.