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 s lime net Labyrinthuloides minuta Watson et Raper and other eukaryotes provide insights into the early branching patterns for protists with t ripartite flagellar hairs, the heterokont stramenopiles. Within this m onophyletic assemblage, heterotrophic bicosoecids and labyrinthulids d iverge before the separation of oomycetes and autotrophic stramenopile s. We infer that stramenopiles evolved from a colourless flagellate. O ther taxa with chloroplasts containing chlorophyll a + c (dinoflagella tes, cryptomonads and haptophytes) represent independent evolutionary lineages that acquired their chloroplasts separately from the endosymb iotic event leading to the autotrophic stramenopiles.