THE STRAMENOPILES FROM A MOLECULAR PERSPECTIVE - 16S-LIKE RIBOSOMAL-RNA SEQUENCES FROM LABYRINTHULOIDES-MINUTA AND CAFETERIA-ROENBERGENSIS

Comparisons of 16S-like ribosomal RNA sequences from the heterotrophic marine flagellate Cafeteria roenbergensis Fenchel et Patterson, the slime net Labyrinthuloides minuta Watson et Raper and other eukaryotes provide insights into the early branching patterns for protists with tripartite flagellar hairs, the heterokont stramenopiles. Within this monophyletic assemblage, heterotrophic bicosoecids and labyrinthulids diverge before the separation of oomycetes and autotrophic stramenopiles. We infer that stramenopiles evolved from a colourless flagellate. Other taxa with chloroplasts containing chlorophyll a + c (dinoflagellates, cryptomonads and haptophytes) represent independent evolutionary lineages that acquired their chloroplasts separately from the endosymbiotic event leading to the autotrophic stramenopiles.