Character evolution and phylogeny of dinoflagellates with complex organelles
The molecular phylogeny of polykrikoids and warnowiids was one of my main research topics. I started these investigations at the University of British Columbia in the Leander laboratoryand now I continue this work with a focus on the taxonomy.
Our hypotheses were: (1) Species containing complex extrusomes like nematocysts are closely related. (2) Species containing complex organelles like ocelloids are closely related. (3) Ocelloid and piston are functionally integrated for predation. Intermediate character states for these complex organelles can be found in modern relatives and can be understood from ontogenetic analyses.
(1) Polykrikoids & warnowiids: Polykrikos and Pheopolykrikos species were and will be isolated from natural plankton samples. DNA was and will be extracted and SSU and LSU rDNA sequences were and will be obtained. LM, TEM and SEM were and will be used to describe the morphological diversity and life-cycles of these dinoflagellates. Nematocyst-taeniocyst-complexes are a characteristic feature of the genus Polykrikos. The genus Pheopolykrikos is not well defined yet and it is questionable whether the cells contain nematocysts. The investigation of warnowiid taxa possessing nematocysts is in progress.
(2 & 3) Warnowiids: Nematodinium, Warnowia, Erythropsidinium and related species will be isolated from natural plankton samples. DNA will be extracted and SSU and LSU rDNA sequences will be obtained. LM, TEM and SEM will be used to describe the ultrastructural diversity and morphogenesis of the complex photoreceptors of these dinoflagellates. Intermediate character states in different species will enable us to reconstruct the transformation series associated with the evolution of these complex organelles. The combination of photoreception apparatus, feeding apparatus, and extrusome type will be analyzed to compare and contrast feeding behaviors in different species. The diversity will be placed in the molecular phylogenetic context established from the DNA sequencing research.
TILLMANN, U. & HOPPENRATH, M. (2013): The life-cycle of the heterotrophic dinoflagellate Polykrikos kofoidii. J. Phycol. 49: 298-317.
HOPPENRATH, M., YUBUKI, N., BACHVAROFF, T.R., & LEANDER, B.S. (2010): Re-classification of Pheoploykrikos hartmannii as Polykrikos (Dinophyceae) based partly on the ultrastructure of complex extrusomes. Europ. J. Protistol. 46: 29-37.
HOPPENRATH, M., BACHVAROFF, T.R., HANDY, S.M., DELWICHE, C.F. & LEANDER, B.S. (2009): Molecular phylogeny of ocelloid-bearing dinoflagellates (Warnowiaceae) as inferred from SSU and LSU rDNA sequences. BMC Evolutionary Biology 9: 116.
HOPPENRATH, M. & LEANDER, B.S. (2007): Morphology and phylogeny of the pseudocolonial dinoflagellates Polykrikos lebourae and Polykrikos herdmanae n. sp. Protist 158: 209-227.
HOPPENRATH, M. & LEANDER, B.S. (2007): Character evolution in polykrikoid dinoflagellates. J. Phycol. 43: 366-377.