Title: Evolutionary losses of photosynthesis in eukaryotic microalgae

Speaker: Prof. Ryoma Kamikawa, Graduate School of Agriculture, Kyoto University [website]

Abstract: 

Photosynthesis converts solar energy into biochemical energy, giving the autotrophic nature to photosynthetic organisms. The photosynthesis-derived net primary production occurred in aquatic environments occupies approximately 50% of the global net primary production. Therefore, eukaryotic microalgae (or photosynthetic unicellular eukaryotes) thriving in aquatic environments substantially contribute to supporting the ecosystems on Earth. Nevertheless, many species of eukaryotic microalgal lineages have evolutionarily lost photosynthesis and have become obligate heterotrophs including phagotrophs and osmotrophs or obligate parasites. Most of the non-photosynthetic eukaryotic microalgae retain plastids even after loss of photosynthesis. Some of the non-photosynthetic plastids still function for representative plastid metabolic pathways, but the others have lost many of them. In this presentation, I will discuss evolutionary principles associated with loss of photosynthesis in microalgae, based on recent research advances on phylogenetic diversity, plastid genome structures, and functions of non-photosynthetic eukaryotic microalgal species.