Chemodiversity of the brown algae Canistrocarpus cervicornis (Dictyotaceae, Phaeophyceae) in tropical and subtropical populations along the southwestern Atlantic coast of Brazil

Three populations of the brown seaweed Canistrocarpus cervicornis along 1800 km of the southwestern Atlantic coast were studied. Phylogenetic analysis based on the plastid and mitochondrial genes rbc L and nad 1, respectively, confirmed that these populations were composed of the same taxon. Crude ethyl acetate extracts were analysed by gas chromatography coupled to a mass spectrometer (GC/MS), which revealed 13 detectable products whose fragment patterns were compatible with those expected for diterpenes. The analysis of fragment patterns identified the diterpenoid 4,7-diacetoxy-14-hydroxydolastane-1 (15), 8-diene as the major product in all the populations. Furthermore, the concentration of this diterpenoid and other products were highly variable among the three populations. However, this plasticity was not observed in sample morphology, which was generally conserved among the populations. Therefore, GC/MS enabled the detection of differences in diterpene chemodiversity within geographically distinct populations of C. cervicornis , and even though natural product abundance varied greatly, molecular markers and morphology were highly conserved.