Dinoflagellates are one of the most widespread and abundant unicellular eukaryotes in aquatic ecosystems, in which they play key roles in carbon cycling. Their ecological success can be related to the extraordinary diversity of their roles, interactions, but also trophic modes, as they can be strictly photosynthetic, strictly heterotrophic, or perform both (mixotrophy) depending on external conditions. Dinoflagellates also exhibit remarkable molecular features including Gb-sized nuclear genomes, permanently condensed chromosomes, and a 10- fold lower ratio of protein to DNA than other eukaryotes. Genomic and transcriptomic studies from the last decade based on cultivated lineages confirmed their remarkable sequence divergence and complexity, revealing millions of « dark » proteins (i.e. they do not share significant similarity to any known sequences). Are these dark proteins lineage-specific? Are dark proteins and genomic novelty linked to organismal traits (e.g., trophic modes, life style, toxicity)? Are dark proteins abundant in the ecosystems? Do they show biogeographical structure and are they particularly expressed in certain niches? DIVEDINO will study the functional diversity of dinoflagellates, in order to link their hyper diversification (e.g., high molecular evolutionary rates, high gene copy numbers, large dark proteomes) to their evolution and ecology. Existing datasets will be gathered and complemented with new transcriptomes obtained from under-represented lineages. The objectives will be:1) Exploring to an unprecedented scale functional diversity using comparative omics, phylogenomics and structure prediction; 2) Linking functional diversity to organismal traits; 3) Investigating how functional diversity and genomic novelty correlate to biotic/abiotic factors in the marine ecosystems. DIVEDINO will constitute the most extensive eco-evolutionary study of these highly divergent lineage, shedding light on the origins of genomic and functional diversity.