Genetic variation within and among north atlantic and baltic populations of the benthic alga phycodrys rubens rhodophyta

Abstract

Genetic variation was examined within and among North Atlantic, North Sea and Baltic populations of the benthic red alga Phycodrys rubens using allozymes and random amplified polymorphic DNA (RAPD) markers. On western and eastern North Atlantic coasts distinct allozyme types were found, with the exception of western Newfoundland where East and West Atlantic types co-occur. Along the European coasts, two genetic groups were distinguished by fixed allelic differences: an outer oceanic group and a North Sea/Baltic group. The two genetic types co-occur in the Skagerrak and Kattegar region. Reproductive isolation between the two types is suggested by the lack of hybrids in the overlap zones, and they may therefore represent sibling species. Unexpectedly, an analysis of RAPD variation was unable to recover the two cryptic species identified. © 1995 The British Phycological Society.