GENETIC STRUCTURE OF NATURAL POPULATIONS IN THE RED ALGAE GELIDIUM CANARIENSE (GELIDIALES, RHODOPHYTA) INVESTIGATED BY RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) MARKERS

Random amplified polymorphic DNA (RAPD) marker variation was analyzed in female gametophytes in natural populations of Gelidium canariense (Grunow) Seoane-Camba ex Haroun, Gil-Rodriguez, Diaz de Castro et Prud'Homme van Reine from the Canary Islands to estimate the degree and distribution of genetic variability and differentiation. A total of 190 haploid individuals were analyzed with 60 polymorphic RAPDs bands which produced 190 distinct multilocus genotypes. A high level of polymorphism was detected in all populations analyzed. Within-population gene diversity ranged from 0.156 to 0.264. The populations on the island of Gran Canaria showed higher genetic variation than the other populations analyzed. The partitioning of molecular variance by analysis of molecular variance showed that most genetic variation resides within populations (68.85%). These results suggest that sexual reproduction is the predominant mode of reproduction for G. canariense gametophytic populations, and the main determinant in reaching high levels of genetic diversity. The Neighbor-Joining tree and FCA analysis displayed two subclusters that correspond to the populations from the western islands (Tenerife, La Palma, Gomera) and the eastern island (Gran Canaria). In addition, we have detected a significant relationship between F sub(ST)-(1-F sub(ST)) and geographical distance consistent with data on water circulation and age of islands. The results obtained agree with an isolation by distance model, with gene flow from eastern to the western islands, and a high level of genetic differentiation between populations (F sub(ST)=0.311, P