Origin of Fucus serratus (Heterokontophyta;: Fucaceae) populations in Iceland and the Faroes:: a microsatellite-based assessment

The common intertidal seaweed Fucus serratus was almost certainly introduced to Iceland and the Faroes by humans from Europe, as previous genetic studies have confirmed that life-history constraints preclude long-distance dispersal. Introduction must have occurred sometime in the 1,000 years between arrival of the first Icelandic settlers c. 900 AD and when the species was first noted in a phycological survey in 1900. We genotyped 19 populations from throughout northern Europe, Iceland, and the Faroes with seven microsatellite loci in order to identify the source or sources of the Icelandic/Faroese populations. Assignment tests indicated that the Smaskjaer area of the Oslofjorden in Norway was the source for the Icelandic populations and the Hafnarfjordur area of Iceland was the likely source for the single Faroese population. The time of introduction to Iceland was probably during the 19th century, whereas introduction to the Faroes occurred during the late 20th century. Additionally, molecular data verified hybridization between the introduced F. serratus and the native F. evanescens.