Analysis of genetic diversity of Furcellaria lumbricalis (Gigartinales, Rhodophyta) in the Baltic Sea by RAPD-PCR technique

Furcellaria lumbricalis (Rhodophyta: Gigartinales) from the Baltic Sea was analysed for genetic diversity using seven RAPD-PCR primers. The algae were collected by SCUBA diving from 12 localities in the Northern and Eastern B altic Sea: 7 sites in the Gulf of Riga, 3 in the Archipelago Sea and 2 in t he Gulf of Finland. Individuals from all the sites were clearly distinguish ed from each other by RAPD-PCR polymorphisms. The 12 samples of F. lumbrica lis were clustered into four groups at a similarity level of 70% in UPGMA a nalysis (unweighted pair group method with arithmetic averages). Two of the se clusters (cluster I from the Gulf of Finland and III from the Gulf of Ri ga) were also clustered in neighbour-joining (NJ) network and in the NJ con sensus tree, but only cluster I was supported by a bootstrap value higher t han 50%. Cluster I also had the highest support (40%) in the phylogenetic m ajority rule and the strict Wagner consensus tree. Thus, according to the r esults, the individuals from the Gulf of Finland were more closely related to each other than to the individuals from two other sampling sites. Also, the two individuals from the Gulf of Riga forming a cluster are probably re lated to each other, while in the rest of the individuals the geographical distribution did not correlate with the geographical distribution. RAPD-PCR technique revealed surprisingly high genetic Variation among F. lumbricali s populations, a finding which is difficult to explain as sexual reproducti on of F. lumbricalis is not known to take place in the areas studied. Thus the genetic diversity observed might be attributed to high levels of drift among small groups of individuals among the habitats or to changes in genom es, such as transposition, gene rearrangement and gene amplification or mos aics of different genotypes.