Open Collections

Cooney, Elizabeth

University of British Columbia

Dinoflagellates are a diverse group of protists with many unique traits including large genomes packaged into permanently condensed chromosomes, photosynthetic or cryptic plastids acquired vertically or horizontally in serial endosymbioses, and in some taxa, highly complex organelles like nematocysts and the eye-like ocelloid. Because these features promise to expand our understanding of eukaryotic biology, reconstructing how they evolved has become a point of interest. To infer ancestral states, robust and well-supported phylogenies generated from high-coverage transcriptomic datasets are needed. So far, these analyses have relied on transcriptome data from cultured taxa, which are mostly photosynthetic. As half of known dinoflagellate species are non-photosynthetic, current phylogenies fail to reflect the diversity that characterizes this group. Here, I generate single cell transcriptomes from over 150 rare and under-sampled dinoflagellates collected from the environment. Using these data, I explore three major heterotrophic lineages of interest: Abedinium, the Noctilucales, and the complex organelle-bearing members of the Gymnodiniales, the warnowiids. In these investigations I reveal that Abedinium is an independent, deep-branching core dinoflagellate lineage, the unique traits of the Noctilucales are derived rather than ancestral, and the heterotrophic warnowiids retain photosynthetic genes except for photosystem II and RuBisCo, suggesting that this mechanism serves an alternate function in the ocelloid. In the final chapter I generate a comprehensive dinoflagellate phylogeny that better represents the proportion of heterotrophic, athecate, and deep- branching taxa in dinoflagellates. This analysis reveals several new insights, including the early acquisition timing of two histone-like protein (HLP) types, the diversity and punctate distribution of microbial rhodopsins, and the common retention of plastid-derived electron transport genes across heterotrophic dinoflagellates.

Text; Moving Image

2022-07-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82189

Botany

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/