Genetics of Morphology and Growth in Laminaria from the North Atlantic Ocean — Implications for Biogeography

Abstract

FI sporophytes produced by inter-and intraspecific crosses of North Atlantic Laminaria were reared in greenhouse culture conditions from February through June, 1989. Growth rates and morphometric variation among different families were assessed throughout this period in order to evaluate phenetic and distributional relationships. Significant differences in grQwth rates were observed among families, with slower rates associated with offspring from the Faeroe Islands and Helgoland, and maximum rates observed in Long Island Sound sporophytes. Between-site and interspecifically-derived offspring showed intermediate growth rates. Morphometric measurements also varied with the type of cross and source of isolates, but stipe length and blade width characteristics seem to be sex-linked. Although no sterility barriers were observed among isolates, and genetic contribution to the measured characters was demonstrated in F I sporophytes, this study substantiates the presence of temperature races of L. saccharina and L. longicruris along the North Atlantic coast